In radio communications, antennas are given a central place; to ensure the best radio communications, antennas should be given the closest attention. In essence, it is the antenna that carries out the radio transmission process itself. Indeed, the transmitting antenna, powered by high-frequency current from the transmitter, converts this current into radio waves and emits them in the desired direction. The receiving antenna carries out the inverse conversion of radio waves into high-frequency current, and the radio receiver carries out further conversions of the received signal.
Radio amateurs, who always want more power to communicate with interesting correspondents as far away as possible, have a maxim - the best amplifier (HF) is an antenna.
For now, I belong to this club of interests somewhat indirectly. There is no amateur radio call sign, but it’s interesting! You can’t work for the program, but you can listen and get an idea, that’s all. Actually, this activity is called radio surveillance. At the same time, it is quite possible to exchange with the radio amateur whom you heard on the air, receipt cards of the established form, in the slang of radio amateurs QSL. Many HF broadcasting stations also welcome confirmation of reception, sometimes encouraging such activity with small souvenirs with the logos of the radio station - it is important for them to know the conditions of reception of their radio broadcasts in different parts of the world.
An observer radio can be quite simple, at least at first. An antenna, a structure by far, is more bulky and expensive, and the lower the frequency, the more bulky and expensive it is - everything is tied to the wavelength.
The bulkiness of antenna structures is largely due to the fact that at low suspension heights, antennas, especially for low-frequency ranges - 160, 80.40 m, do not work well. So what makes them bulky is precisely the masts with guys, and the lengths are tens, sometimes hundreds of meters. In short, not particularly miniature things. It would be nice to have a separate field for them near the house. Well, it depends.
So, an asymmetrical dipole.
Above is a diagram of several options. The MMNA mentioned there is a program for modeling antennas.
The conditions on the ground turned out to be such that a two-part version of 55 and 29m fit comfortably. I stopped there.
A few words about the radiation pattern.
The antenna has 4 petals, “pressed” to the canvas. The higher the frequency, the more they “press” against the antenna. But truth and empowerment mean more. So on this principle
It is possible to build completely directional antennas, which, however, unlike the “correct” ones, do not have particularly high gain. So you need to place this antenna taking into account its radiation pattern.
The antenna on all bands indicated in the diagram has SWR (standing wave ratio, a very important parameter for an antenna) within reasonable limits for HF.
To match an asymmetrical dipole - also known as Windom - you need a SHPTDL (broadband transformer on long lines). Behind this terrible name lies a relatively simple design.
It looks something like this.
So what was done.
First of all, I decided on strategic issues.
I made sure that the basic materials were available, mainly, of course, suitable wire for the antenna fabric in the required quantity.
I decided on the location of the suspension and the “masts”. The recommended suspension height is 10m. My wooden mast, standing on the roof of the woodshed, was twisted in the spring by the frozen snow - it didn’t last long, what a pity, I had to remove it. It was decided for now to hook one side to the ridge of the roof; the height would be about 7m. Not enough, of course, but cheap and cheerful. It was convenient to hang the other side on the linden tree standing opposite the house. The height there was 13...14m.
What was used.
Tools.
Soldering iron, of course, with accessories. Power, watts, about forty. Tools for radio installation and small plumbing. Anything drilling. A powerful electric drill with a long drill bit for wood was very useful - pass the coaxial cable through the wall. Of course there is an extension cord for it. I used hot glue. There will be work at heights - it is worth taking care of suitable, strong ladders. It really helps to feel more confident, away from the ground, wearing a safety belt - like the ones that fitters have on poles. Climbing up, of course, is not very convenient, but you can work “there”, with both hands and without much fear.
Materials.
The most important thing is the material for the canvas. I used a “vole” - a field telephone wire.
Coaxial cable for reduction as needed.
A few radio components, a capacitor and resistors according to the diagram. Two identical ferrite tubes from RF filters on the cables. Thimbles and fasteners for thin wire. A small block (roller) with an ear mount. A suitable plastic box for the transformer. Ceramic insulators for antenna. Nylon rope of suitable thickness.
What was done.
First of all, I measured (seven times) pieces of wires for the canvas. With some reserve. Cut it off (once).
I set about making a transformer in a box.
I selected ferrite tubes for the magnetic core. It is made of two identical ferrite tubes from filters on monitor cables. Nowadays old CRT monitors are simply thrown away and finding “tails” from them is not particularly difficult. You can ask around with your friends, probably someone else is collecting dust in their attics or garage. Good luck if you know system administrators. After all, in our time, when switching power supplies are everywhere and the fight for electromagnetic compatibility is serious, filters on cables can be found in many places, moreover, such ferrite products are vulgarly sold in electronic component stores.
Selected identical tubes are folded like binoculars and secured with several layers of adhesive tape. The winding is made of mounting wire of the maximum possible cross-section, such that the entire winding fits in the windows of the magnetic circuit. It didn’t work out the first time and I had to proceed by trial and error, fortunately there were very few turns. In my case, I didn’t have a suitable section at hand and had to wind two wires at the same time, making sure in the process that they did not overlap.
To obtain a secondary winding, we make two turns with two wires folded together, then pull each end of the secondary winding back (to the opposite side of the tube), we get three turns with a midpoint.
The central insulator is made from a piece of fairly thick PCB. There are special ceramic ones specifically for antennas; it is better, of course, to use them. Since all laminated plastics are porous and, as a result, very hygroscopic, so that the antenna parameters do not “float”, the insulator should be thoroughly impregnated with varnish. I used oil glyphthalic, yacht.
The ends of the wires are cleared of insulation, passed through the holes several times and thoroughly soldered with zinc chloride (Soldering Acid flux) so that the steel wires are also soldered. The soldering areas are washed very thoroughly with water to remove flux residues. It can be seen that the ends of the wires are pre-threaded into the holes of the box where the transformer will sit, otherwise you will then have to thread all 55 and 29 meters into the same holes.
I soldered the corresponding leads of the transformer to the cutting points, shortening these leads to a minimum. Don’t forget to try it on the box before each action so that everything fits.
From a piece of PCB from an old printed circuit board, I cut a circle into the bottom of the box, there are two rows of holes in it. Through these holes, a coaxial cable is attached using a bandage made of thick synthetic threads. The one in the photo is far from the best in this application. This is a television with foam insulation of the central core, the core itself is “mono”, for screw-on TV connectors. But there was a cove of trophy available. I applied it. The circle and bandage are thoroughly varnished and dried. The end of the cable is pre-cut.
The remaining elements are soldered, the resistor is made up of four. Everything was filled with hot glue, probably in vain - it turned out a bit heavy.
Ready-made transformer in the house, with “conclusions”.
In the meantime, a fastening to the ridge was made - there are two boards at the very top. Long strips of roofing steel, 1.5mm stainless steel loop. The ends of the rings are welded. On the strips, along a row of six holes for self-tapping screws, distribute the load.
The block has been prepared.
I didn’t get ceramic antenna “nuts”, I used vulgar rollers from old wiring, fortunately, they are still found in old village houses for demolition. Three pieces on each edge - the better the antenna is isolated from the ground, the weaker the signals it can receive.
The field wire used has woven steel cores and can withstand stretching well. In addition, it is designed for laying outdoors, which is also quite suitable for our case. Radio amateurs quite often make wire antenna sheets from it, and the wire has proven itself well. Some experience has been accumulated in its specific application, which, first of all, says that you should not bend the wire too much - the insulation bursts in the cold, moisture gets on the wires and they begin to oxidize, in that place, after a while, the wire breaks.
Shortwave antennas
Practical Amateur Radio Antenna Designs
The section presents a large number of different practical designs of antennas and other related devices. To make your search easier, you can use the “View list of all published antennas” button. For more on the topic, see the subtitle CATEGORY, which is regularly updated with new publications.
Dipole with off-center feed point
Many shortwave operators are interested in simple HF antennas that provide operation on several amateur bands without any switching. The most famous of these antennas is Windom with a single-wire feeder. But the price for the simplicity of manufacturing this antenna was and remains the inevitable interference with television and radio broadcasting when powered by a single-wire feeder and the accompanying showdown with neighbors.
The idea of Windom dipoles seems simple. By shifting the feed point from the center of the dipole, you can find a ratio of arm lengths at which the input impedances on several ranges become quite close. Most often, they look for sizes at which it is close to 200 or 300 Ohms, and matching with low-impedance power cables is carried out using balun transformers (BALUN) with a transformation ratio of 1:4 or 1:6 (for a cable with a characteristic impedance of 50 Ohms). This is exactly how, for example, the FD-3 and FD-4 antennas are made, which are produced, in particular, mass-produced in Germany.
Radio amateurs construct similar antennas on their own. Certain difficulties, however, arise in the manufacture of balun transformers, in particular, for operation in the entire short-wave range and when using power exceeding 100 W.
A more serious problem is that such transformers only work normally for a matched load. And this condition is obviously not met in this case - the input impedance of such antennas is really close to the required values of 200 or 300, but obviously differs from them, and on all bands. The consequence of this is that, to some extent, the antenna effect of the feeder is preserved in this design despite the use of a matching transformer and coaxial cable. And as a result, the use of balun transformers in these antennas, even of a rather complex design, does not always completely solve the TVI problem.
Alexander Shevelev (DL1BPD) managed, using matching devices on lines, to develop a variant for matching Windom dipoles that use power through a coaxial cable and are free of this drawback. They were described in the magazine “Radio Amateur. Bulletin of the SRR" (2005, March, pp. 21, 22).
As calculations show, the best result is obtained when using lines with wave impedances of 600 and 75 Ohms. A line with a characteristic impedance of 600 Ohms adjusts the input impedance of the antenna on all operating ranges to a value of approximately 110 Ohms, and a 75 Ohm line transforms this impedance to a value close to 50 Ohms.
Let's consider the option of making such a Windom dipole (ranges 40-20-10 meters). In Fig. 1 shows the lengths of the arms and dipole lines in these ranges for a wire with a diameter of 1.6 mm. The total length of the antenna is 19.9 m. When using an insulated antenna cord, the arm lengths are made slightly shorter. A line with a characteristic impedance of 600 Ohms and a length of approximately 1.15 meters is connected to it, and a coaxial cable with a characteristic impedance of 75 Ohms is connected to the end of this line.
The latter, with a cable shortening coefficient of K=0.66, has a length of 9.35 m. The given line length with a characteristic impedance of 600 Ohms corresponds to a shortening coefficient K=0.95. With these dimensions, the antenna is optimized for operation in the frequency bands 7...7.3 MHz, 14...14.35 MHz and 28...29 MHz (with a minimum SWR at 28.5 MHz). The calculated SWR graph of this antenna for an installation height of 10 m is shown in Fig. 2.
Using a cable with a characteristic impedance of 75 Ohms in this case is generally not the best option. Lower SWR values can be obtained by using a cable with a characteristic impedance of 93 Ohms or a line with a characteristic impedance of 100 Ohms. It can be made from a coaxial cable with a characteristic impedance of 50 Ohms (for example, http://dx.ardi.lv/Cables.html). If a line with a characteristic impedance of 100 Ohms is used from a cable, it is advisable to turn on BALUN 1:1 at its end.
To reduce the level of interference, a choke should be made from a part of the cable with a characteristic impedance of 75 Ohms - a coil (coil) Ø 15-20 cm, containing 8-10 turns.
The radiation pattern of this antenna is practically no different from the radiation pattern of a similar Windom dipole with a balun transformer. Its efficiency should be slightly higher than that of antennas using BALUN, and tuning should be no more difficult than tuning conventional Windom dipoles.
Vertical dipole
It is well known that for operation on long-distance routes, a vertical antenna has an advantage, since its radiation pattern in the horizontal plane is circular, and the main lobe of the pattern in the vertical plane is pressed to the horizon and has a low level of radiation at the zenith.
However, the manufacture of a vertical antenna involves solving a number of design problems. The use of aluminum pipes as a vibrator and the need for its effective operation to install a system of “radials” (counterweights) at the base of the “vertical”, consisting of a large number of quarter-wave length wires. If you use a wire rather than a pipe as a vibrator, the mast supporting it must be made of dielectric and all guy wires supporting the dielectric mast must also be dielectric, or broken into non-resonant sections with insulators. All this is associated with costs and is often structurally impossible, for example, due to the lack of the necessary area to accommodate the antenna. Do not forget that the input impedance of “verticals” is usually below 50 Ohms, and this will also require its coordination with the feeder.
On the other hand, horizontal dipole antennas, which include Inverted V antennas, are very simple and cheap in design, which explains their popularity. The vibrators of such antennas can be made from almost any wire, and the masts for their installation can also be made from any material. The input impedance of horizontal dipoles or Inverted V is close to 50 ohms, and often you can do without additional matching. The radiation patterns of the Inverted V antenna are shown in Fig. 1.
The disadvantages of horizontal dipoles include their non-circular radiation pattern in the horizontal plane and a large radiation angle in the vertical plane, which is mainly acceptable for working on short paths.
We rotate the usual horizontal wire dipole vertically by 90 degrees. and we get a vertical full-size dipole. To reduce its length (in this case height), we use a well-known solution - a “dipole with bent ends”. For example, a description of such an antenna is in the files of I. Goncharenko’s library (DL2KQ) for the MMANA-GAL program - AntShortCurvedCurved dipole.maa. By bending some of the vibrators, we, of course, lose somewhat in the antenna gain, but significantly gain in the required mast height. The bent ends of the vibrators must be located one above the other, while the radiation of vibrations with horizontal polarization, which is harmful in our case, is compensated. A sketch of the proposed antenna option, called Curved Vertical Dipole (CVD) by the authors, is presented in Fig. 2.
Initial conditions: a dielectric mast 6 m high (fiberglass or dry wood), the ends of the vibrators are pulled with a dielectric cord (fishing line or nylon) at a slight angle to the horizontal. The vibrator is made of copper wire with a diameter of 1...2 mm, bare or insulated. At the break points, the vibrator wire is attached to the mast.
If we compare the calculated parameters of the Inverted V and CVD antennas for the 14 MHz range, it is easy to see that due to the shortening of the radiating part of the dipole, the CVD antenna has 5 dB less gain, however, at a radiation angle of 24 degrees. (maximum CVD gain) the difference is only 1.6 dB. In addition, the Inverted V antenna has a radiation pattern unevenness in the horizontal plane that reaches 0.7 dB, i.e. in some directions it outperforms CVD in gain by only 1 dB. Since the calculated parameters of both antennas turned out to be close, only an experimental test of CVD and practical work on the air could help make a final conclusion. Three CVD antennas were manufactured for the ranges of 14, 18 and 28 MHz according to the dimensions indicated in the table. They all had the same design (see Fig. 2). The dimensions of the upper and lower arms of the dipole are the same. Our vibrators were made of field telephone cable P-274, insulators were made of plexiglass. The antennas were mounted on a 6 m high fiberglass mast, with the top point of each antenna being 6 m above the ground. The bent parts of the vibrators were pulled back with a nylon cord at an angle of 20-30 degrees. to the horizon, since we did not have high objects for attaching guy wires. The authors were convinced (this was also confirmed by modeling) that the deviation of the bent sections of the vibrators from the horizontal position was 20-30 degrees. has virtually no effect on CVD characteristics.
Simulations in MMANA show that such a curved vertical dipole is easily compatible with 50 ohm coaxial cable. It has a small radiation angle in the vertical plane and a circular radiation pattern in the horizontal (Fig. 3).
The design simplicity made it possible to change one antenna to another within five minutes, even in the dark. The same coaxial cable was used to power all CVD antenna options. He approached the vibrator at an angle of about 45 degrees. To suppress common-mode current, a tubular ferrite magnetic core (catch filter) is installed on the cable near the connection point. It is advisable to install several similar magnetic cores on a section of cable 2...3 m long in the vicinity of the antenna fabric.
Since the antennas were made from vole, its insulation increased the electrical length by about 1%. Therefore, antennas made according to the dimensions given in the table needed some shortening. The adjustment was made by adjusting the length of the lower bent section of the vibrator, easily accessible from the ground. By folding part of the length of the lower bent wire into two, you can fine-tune the resonant frequency by moving the end of the bent section along the wire (a kind of tuning loop).
The resonant frequency of the antennas was measured with an MF-269 antenna analyzer. All antennas had a clearly defined minimum SWR within the amateur bands, which did not exceed 1.5. For example, for an antenna on the 14 MHz band, the minimum SWR at a frequency of 14155 kHz was 1.1, and the bandwidth was 310 kHz at the SWR 1.5 level and 800 kHz at the SWR 2 level.
For comparative tests, an Inverted V of the 14 MHz range was used, mounted on a metal mast 6 m high. The ends of its vibrators were at a height of 2.5 m above the ground.
To obtain objective estimates of signal strength under QSB conditions, the antennas were repeatedly switched from one to another with a switching time of no more than one second.
Table
Radio communications were carried out in SSB mode with a transmitter power of 100 W on routes ranging from 80 to 4600 km. On the 14 MHz band, for example, all correspondents located at a distance of more than 1000 km noted that the signal level with the CVD antenna was one or two points higher than with the Inverted V. At a distance of less than 1000 km, the Inverted V had some minimal advantage .
These tests were carried out during a period of relatively poor radio wave conditions on the HF bands, which explains the lack of longer-distance communications.
During the period of absence of ionospheric transmission in the 28 MHz range, we conducted several surface wave radio communications with Moscow shortwave radios from our QTH with this antenna over a distance of about 80 km. It was impossible to hear any of them on a horizontal dipole, even raised slightly higher than the CVD antenna.
The antenna is made of cheap materials and does not require much space for placement.
When used as guy ropes, nylon fishing line can easily be disguised as a flagpole (a cable divided into sections of 1.5...3 m with ferrite chokes, and can run along or inside the mast and be unnoticeable), which is especially valuable with unfriendly neighbors in the countryside (Fig. 4).
Files in .maa format for independent study of the properties of the described antennas are located.
Vladislav Shcherbakov (RU3ARJ), Sergey Filippov (RW3ACQ),
Moscow
A modification of the well-known T2FD antenna is proposed, which allows you to cover the entire range of amateur radio HF frequencies, losing quite a bit to a half-wave dipole in the 160 meter range (0.5 dB on short-range and about 1.0 dB on DX routes). 
If repeated exactly, the antenna starts working immediately and does not need adjustment. A peculiarity of the antenna was noted: static interference is not perceived, and in comparison with a classic half-wave dipole. In this version, the reception of the broadcast turns out to be quite comfortable. Very weak DX stations can be listened to normally, especially on low frequency bands.
Long-term operation of the antenna (more than 8 years) allowed it to deservedly be classified as a low-noise receiving antenna. Otherwise, in terms of efficiency, this antenna is practically not inferior to a half-wave dipole or Inverted Vee on any of the ranges from 3.5 to 28 MHz.
And one more observation (based on feedback from distant correspondents) - there are no deep QSBs during communications. Of the 23 modifications of this antenna produced, the one proposed here deserves special attention and can be recommended for mass repetition. All proposed dimensions of the antenna-feeder system are calculated and accurately verified in practice.
Antenna fabric
The dimensions of the vibrator are shown in the figure. The halves (both) of the vibrator are symmetrical, the excess length of the “internal corner” is cut on the spot, and a small platform (necessarily insulated) is also attached there for connection to the supply line. Ballast resistor 240 Ohm, film (green), rated for 10 W power. You can also use any other resistor of the same power, the main thing is that the resistance must be non-inductive. Copper wire - insulated, with a cross-section of 2.5 mm. Spacers are wooden slats cut into sections with a cross-section of 1 x 1 cm and coated with varnish. The distance between the holes is 87 cm. We use a nylon cord for the guy wires.
Overhead power line
For the power line we use PV-1 copper wire, 1 mm cross-section, vinyl plastic spacers. The distance between the conductors is 7.5 cm. The length of the entire line is 11 meters.
Author's installation option
A metal mast grounded from below is used. The mast is installed on a 5-story building. The mast is 8 meters made of Ø 50 mm pipe. The ends of the antenna are located 2 m from the roof. The core of the matching transformer (SHPTR) is made from a TVS-90LTs5 line transformer. The coils there are removed, the core itself is glued with Supermoment glue to a monolithic state and with three layers of varnished fabric.
The winding is made in 2 wires without twisting. The transformer contains 16 turns of single-core insulated copper wire Ø 1 mm. The transformer has a square (sometimes rectangular) shape, so 4 pairs of turns are wound on each of the 4 sides - the best option for current distribution.
The SWR in the entire range is from 1.1 to 1.4. The SHTR is placed in a tin screen well sealed with the feeder braid. From the inside, the middle terminal of the transformer winding is securely soldered to it.
After assembly and installation, the antenna will work immediately and in almost any conditions, that is, located low above the ground or above the roof of the house. It has a very low level of TVI (television interference), and this may additionally be of interest to radio amateurs working from villages or summer residents.
Loop Feed Array Yagi antenna for 50 MHz band
Yagi antennas with a frame vibrator located in the plane of the antenna are called LFA Yagi (Loop Feed Array Yagi) and are characterized by a larger operating frequency range than conventional Yagi. One popular LFA Yagi is Justin Johnson's 5-element design (G3KSC) on 6 meters.
The antenna diagram, distances between elements and dimensions of the elements are shown below in the table and drawing.
Dimensions of the elements, distances to the reflector and diameters of the aluminum tubes from which the elements are made according to the table: The elements are installed on a traverse about 4.3 m long from a square aluminum profile with a cross-section of 90×30 mm through insulating transition strips. The vibrator is powered via a 50-ohm coaxial cable through a balun transformer 
1:1.
Tuning the antenna to the minimum SWR in the middle of the range is done by selecting the position of the end U-shaped parts of the vibrator from tubes with a diameter of 10 mm. The position of these inserts must be changed symmetrically, i.e., if the right insert is pulled out by 1 cm, then the left one needs to be pulled out by the same amount.
SWR meter on strip lines
SWR meters, widely known from amateur radio literature, are made using directional couplers and are a single-layer 
coil or ferrite ring core with several turns of wire. These devices have a number of disadvantages, the main one of which is that when measuring high powers, high-frequency “interference” appears in the measuring circuit, which requires additional costs and efforts to shield the detector part of the SWR meter to reduce the measurement error, and with the formal attitude of the radio amateur to the manufacture device, the SWR meter can cause a change in the wave impedance of the feeder line depending on the frequency. The proposed SWR meter based on strip directional couplers is devoid of such disadvantages, is structurally designed as a separate independent device and allows you to determine the ratio of direct and reflected waves in the antenna circuit with an input power of up to 200 W in the frequency range 1...50 MHz at the characteristic impedance of the feed line 50 Ohm. If you only need to have an indicator of the transmitter output power or monitor the antenna current, you can use the following device: When measuring SWR in lines with a characteristic impedance other than 50 Ohms, the values of resistors R1 and R2 should be changed to the value of the characteristic impedance of the line being measured.
SWR meter design
The SWR meter is made on a board made of double-sided fluoroplastic foil 2 mm thick. As a replacement, it is possible to use double-sided fiberglass.
Line L2 is made on the back side of the board and is shown as a broken line. Its dimensions are 11x70 mm. Pistons are inserted into the holes in line L2 for connectors XS1 and XS2, which are flared and soldered together with L2. The common bus on both sides of the board has the same configuration and is shaded on the board diagram. Holes are drilled in the corners of the board into which pieces of wire with a diameter of 2 mm are inserted, soldered on both sides of the common bus. Lines L1 and L3 are located on the front side of the board and have dimensions: a straight section of 2x20 mm, the distance between them is 4 mm and are located symmetrically to the longitudinal axis of line L2. The displacement between them along the longitudinal axis L2 is 10 mm. All radio elements are located on the side of the strip lines L1 and L2 and are soldered overlapping directly to the printed conductors of the SWR meter board. The printed circuit board conductors should be silver plated. The assembled board is soldered directly to the contacts of connectors XS1 and XS2. The use of additional connecting conductors or coaxial cable is prohibited. The finished SWR meter is placed in a box made of non-magnetic material 3...4 mm thick. The common bus of the SWR meter board, the device body and connectors are electrically connected to each other. The SWR reading is carried out as follows: in the S1 “Direct” position, using R3, set the microammeter needle to the maximum value (100 μA) and by turning S1 to “Reverse”, the SWR value is counted. In this case, the device reading of 0 µA corresponds to SWR 1; 10 µA - SWR 1.22; 20 µA - SWR 1.5; 30 µA - SWR 1.85; 40 µA - SWR 2.33; 50 µA - SWR 3; 60 µA - SWR 4; 70 µA - SWR 5.67; 80 µA - 9; 90 µA - SWR 19.
Nine-band HF antenna
The antenna is a variation of the well-known multi-band WINDOM antenna, in which the feed point is offset from the center. In this case, the input impedance of the antenna in several amateur HF bands is approximately 300 Ohms, 
which allows you to use both a single wire and a two-wire line with the appropriate characteristic impedance as a feeder, and, finally, a coaxial cable connected through a matching transformer. In order for the antenna to operate in all nine amateur HF bands (1.8; 3.5; 7; 10; 14; 18; 21; 24 and 28 MHz), essentially two “WINDOM” antennas are connected in parallel (see above Fig. a): one with a total length of about 78 m (l/2 for the 1.8 MHz band), and the other with a total length of approximately 14 m (l/2 for the 10 MHz band and l for the 21 MHz band). Both emitters are powered by the same coaxial cable with a characteristic impedance of 50 Ohms. The matching transformer has a resistance transformation ratio of 1:6.
The approximate location of the antenna emitters in plan is shown in Fig. b. 
When installing the antenna at a height of 8 m above a well-conducting “ground”, the standing wave coefficient in the range of 1.8 MHz did not exceed 1.3, in the ranges of 3.5, 14, 21, 24 and 28 MHz - 1.5, in the ranges of 7, 10 and 18 MHz - 1.2. In the ranges of 1.8, 3.5 MHz and to some extent in the 7 MHz range at a suspension height of 8 m, the dipole is known to radiate mainly at large angles to the horizon. Consequently, in this case, the antenna will be effective only for short-range communications (up to 1500 km).
The connection diagram for the windings of the matching transformer to obtain a transformation ratio of 1:6 is shown in Fig. c.
Windings I and II have the same number of turns (as in a conventional transformer with a transformation ratio of 1:4). If the total number of turns of these windings (and it depends primarily on the size of the magnetic core and its initial magnetic permeability) is equal to n1, then the number of turns n2 from the connection point of windings I and II to the tap is calculated using the formula n2 = 0.82n1.t
Horizontal frames are very popular. Rick Rogers (KI8GX) has experimented with a "tilt frame" attached to a single mast.
To install the “inclined frame” option with a perimeter of 41.5 m, a mast with a height of 10...12 meters and an auxiliary support with a height of about two meters are required. The opposite corners of the frame, which is shaped like a square, are attached to these masts. The distance between the masts is chosen such that the angle of inclination of the frame relative to the ground is within 30...45°. The feed point of the frame is located in the upper corner of the square. The frame is powered by a coaxial cable with a characteristic impedance of 50 Ohms. According to KI8GX measurements, in this version the frame had SWR=1.2 (minimum) at a frequency of 7200 kHz, SWR=1.5 (a rather “dumb” minimum) at frequencies above 14100 kHz, SWR=2.3 throughout the entire 21 MHz range, SWR=1.5 (minimum) at a frequency of 28400 kHz. At the edges of the ranges, the SWR value did not exceed 2.5. According to the author, a slight increase in the length of the frame will shift the minima closer to the telegraph sections and will make it possible to obtain an SWR of less than 2 within all operating ranges (except 21 MHz).
QST No. 4 2002
Vertical antenna for 10, 15 meters
A simple combined vertical antenna for the 10 and 15 m bands can be made both for work in stationary conditions and for out-of-town trips. The antenna is a vertical emitter (Fig. 1) with a blocking filter (ladder) and two resonant counterweights. The ladder is tuned to the selected frequency in the 10 m range, so in this range the emitter is element L1 (see figure). In the 15m range, the ladder inductor is an extension coil and, together with the L2 element (see figure), brings the total length of the emitter to 1/4 of the wavelength on the 15m range. The emitter elements can be made from pipes (in a stationary antenna) or from wire (for a traveling antenna). antennas) mounted on fiberglass pipes. A “trap” antenna is less “capricious” to set up and operate than an antenna consisting of two adjacent radiators. The dimensions of the antenna are shown in Fig. 2. 
The emitter consists of several sections of duralumin pipes of different diameters, connected to one another through adapter bushings. The antenna is powered by a 50-ohm coaxial cable. To prevent RF current from flowing through the outer side of the cable braid, power is supplied through a current balun (Fig. 3) made on an FT140-77 ring core. 
The winding consists of four turns of RG174 coaxial cable. The electrical strength of this cable is sufficient to operate a transmitter with an output power of up to 150 W. When working with a more powerful transmitter, you should use either a cable with a Teflon dielectric (for example, RG188), or a large-diameter cable, for winding of which, of course, you will need a ferrite ring of the appropriate size. The balun is installed in a suitable dielectric box:
It is recommended that a non-inductive two-watt resistor with a resistance of 33 kOhm be installed between the vertical emitter and the support pipe on which the antenna is mounted, which will prevent the accumulation of static charge on the antenna. It is convenient to place the resistor in the box in which the balun is installed. The design of the ladder can be any.
Thus, the inductor can be wound on a piece of PVC pipe with a diameter of 25 mm and a wall thickness of 2.3 mm (the lower and upper parts of the emitter are inserted into this pipe). The coil contains 7 turns of copper wire with a diameter of 1.5 mm in varnish insulation, wound in increments of 1-2 mm. The required coil inductance is 1.16 µH. A high-voltage (6 kV) ceramic capacitor with a capacity of 27 pF is connected in parallel to the coil, and the result is a parallel oscillating circuit with a frequency of 28.4 MHz.
Fine tuning of the resonant frequency of the circuit is carried out by compressing or stretching the turns of the coil. After adjustment, the turns are fixed with glue, but it should be borne in mind that an excessive amount of glue applied to the coil can significantly change its inductance and lead to an increase in dielectric losses and, accordingly, a decrease in the efficiency of the antenna. In addition, the ladder can be made from coaxial cable, wound 5 turns on a PVC pipe with a diameter of 20 mm, but it is necessary to provide the possibility of changing the winding pitch to ensure precise tuning to the required resonant frequency. The design of the ladder for its calculation is very convenient to use the Coax Trap program, which can be downloaded from the Internet.
Practice shows that such ladders work reliably with 100-watt transceivers. To protect the drain from environmental influences, it is placed in a plastic pipe, which is closed with a plug on top. Counterweights can be made from bare wire with a diameter of 1 mm, and it is advisable to space them as far apart as possible. If plastic insulated wires are used for counterweights, they should be shortened somewhat. Thus, counterweights made of copper wire with a diameter of 1.2 mm in vinyl insulation with a thickness of 0.5 mm should have a length of 2.5 and 3.43 m for the 10 and 15 m ranges, respectively.
Antenna tuning begins in the 10 m range, after making sure that the ladder is tuned to the selected resonant frequency (for example, 28.4 MHz). The minimum SWR in the feeder is achieved by changing the length of the lower (to the ladder) part of the emitter. If this procedure is unsuccessful, then you will have to change within small limits the angle at which the counterweight is located relative to the emitter, the length of the counterweight and, possibly, its location in space. Only after this do they begin to tune the antenna in the range of 15 m. By changing the length of the top (after the ladder ) parts of the emitter achieve a minimum SWR. If it is impossible to achieve an acceptable SWR, then the solutions recommended for tuning the 10 m range antenna should be applied. In the prototype antenna in the frequency bands 28.0-29.0 and 21.0-21.45 MHz, the SWR did not exceed 1.5.
Tuning Antennas and Circuits Using a Jammer
To work with this noise generator circuit, you can use any type of relay with the appropriate supply voltage and a normally closed contact. Moreover, the higher the relay supply voltage, the higher the level of interference created by the generator. To reduce the level of interference to the devices being tested, it is necessary to carefully shield the generator, and power it from a battery or accumulator to prevent interference from entering the network. In addition to setting up noise-resistant devices, such a noise generator can be used to measure and set up high-frequency equipment and its components.
Determination of the resonant frequency of the circuits and the resonant frequency of the antenna
When using a continuous range survey receiver or wave meter, you can determine the resonant frequency of the circuit under test from the maximum noise level at the output of the receiver or wave meter. To eliminate the influence of the generator and receiver on the parameters of the measured circuit, their coupling coils must have the minimum possible connection with the circuit. When connecting the interference generator to the WA1 antenna under test, you can similarly determine its resonant frequency or frequencies by measuring the circuit.
I. Grigorov, RK3ZK
Wideband aperiodic antenna T2FD
The construction of low-frequency antennas, due to their large linear dimensions, causes radio amateurs quite certain difficulties due to the lack of space necessary for these purposes, the complexity of manufacturing and installing high masts. Therefore, when working on surrogate antennas, many use interesting low-frequency bands mainly for local communications with a “one hundred watt per kilometer” amplifier.
In amateur radio literature there are descriptions of fairly effective vertical antennas, which, according to the authors, “take up virtually no area.” But it is worth remembering that a significant amount of space is required to accommodate the system of counterweights (without which a vertical antenna is ineffective). Therefore, in terms of the occupied area, it is more profitable to use linear antennas, especially those made of the popular “inverted V” type, since their construction requires only one mast. However, turning such an antenna into a dual-band antenna greatly increases the occupied area, since it is desirable to place emitters of different ranges in different planes.
Attempts to use switchable extension elements, customized power lines and other methods of turning a piece of wire into an all-band antenna (with available suspension heights of 12-20 meters) most often lead to the creation of “super surrogates”, by configuring which you can conduct amazing tests of your nervous system.
The proposed antenna is not “super-efficient”, but it allows normal operation in two or three bands without any switching, is characterized by relative stability of parameters and does not require painstaking tuning. Having a high input impedance at low suspension heights, it provides better efficiency than simple wire antennas. This is a slightly modified well-known T2FD antenna, popular in the late 60s, unfortunately, almost never used at present. Obviously, it fell into the category of “forgotten” because of the absorption resistor, which dissipates up to 35% of the transmitter power. It is precisely for fear of losing these percentages that many consider the T2FD to be a frivolous design, although they calmly use a pin with three counterweights in the HF ranges, efficiency. which does not always reach 30%. I had to hear a lot of “against” in relation to the proposed antenna, often without any justification. I will try to briefly outline the pros that made the T2FD chosen for operation on the low frequency bands.
In an aperiodic antenna, which in its simplest form is a conductor with a characteristic impedance Z, loaded with an absorption resistance Rh=Z, the incident wave, upon reaching the load Rh, is not reflected, but is completely absorbed. Due to this, a traveling wave mode is established, which is characterized by a constant maximum current value Imax along the entire conductor. In Fig. 1(A) shows the current distribution along the half-wave vibrator, and Fig. 1(B) - along the traveling wave antenna (losses due to radiation and in the antenna conductor are not taken into account. The shaded area is called the current area and is used to compare simple wire antennas.
In antenna theory, there is the concept of an effective (electric) antenna length, which is determined by replacing a real vibrator with an imaginary one, along which the current is distributed evenly, having the same value Imax, 
the same as for the vibrator under study (i.e., the same as in Fig. 1(B)). The length of the imaginary vibrator is chosen such that the geometric area of the current of the real vibrator is equal to the geometric area of the imaginary one. For a half-wave vibrator, the length of the imaginary vibrator, at which the current areas are equal, is equal to L/3.14 [pi], where L is the wavelength in meters. It is not difficult to calculate that the length of a half-wave dipole with geometric dimensions = 42 m (3.5 MHz range) is electrically equal to 26 meters, which is the effective length of the dipole. Returning to Fig. 1(B), it is easy to find that the effective length of an aperiodic antenna is almost equal to its geometric length.
The experiments carried out in the 3.5 MHz range allow us to recommend this antenna to radio amateurs as a good cost-benefit option. An important advantage of T2FD is its broadband and performance at “ridiculous” suspension heights for low frequency bands, starting from 12-15 meters. For example, an 80-meter dipole with such a suspension height turns into a “military” anti-aircraft antenna, 
because radiates upward about 80% of the supplied power. The main dimensions and design of the antenna are shown in Fig. 2. In Fig. 3 - the upper part of the mast, where the matching-balun transformer T and absorbing resistance R are installed. Transformer design in Fig. 4 
A transformer can be made on almost any magnetic core with a permeability of 600-2000 NN. For example, a core from the fuel assembly of tube TVs or a pair of rings with a diameter of 32-36 mm folded together. It contains three windings wound into two wires, for example MGTF-0.75 sq. mm (used by the author). The cross section depends on the power supplied to the antenna. The winding wires are laid tightly, without pitch or twists. The wires should be crossed in the place indicated in Fig. 4.
It is enough to wind 6-12 turns in each winding. If you carefully examine Fig. 4, the manufacture of a transformer does not cause any difficulties. The core should be protected from corrosion with varnish, preferably oil or moisture-resistant glue. The absorber should theoretically dissipate 35% of the input power. It has been experimentally established that MLT-2 resistors, in the absence of direct current at KB frequencies, can withstand 5-6-fold overloads. With a power of 200 W, 15-18 MLT-2 resistors connected in parallel are sufficient. The resulting resistance should be in the range of 360-390 Ohms. With the dimensions indicated in Fig. 2, the antenna operates in the ranges of 3.5-14 MHz.
To operate in the 1.8 MHz band, it is advisable to increase the total length of the antenna to at least 35 meters, ideally 50-56 meters. If the T transformer is installed correctly, the antenna does not need any adjustment, you just need to make sure that the SWR is in the range of 1.2-1.5. Otherwise, the error should be sought in the transformer. It should be noted that with the popular 4:1 transformer based on a long line (one winding in two wires), the performance of the antenna deteriorates sharply, and the SWR can be 1.2-1.3.
German Quad Antenna at 80, 40, 20, 15, 10 and even 2 m
Most urban radio amateurs are faced with the problem of placing a shortwave antenna due to limited space.
But if there is space for hanging a wire antenna, then the author suggests using it and making a “GERMAN Quad /images/book/antenna”. He reports that it works well on 6 amateur bands: 80, 40, 20, 15, 10 and even 2 meters. The antenna diagram is shown in the figure. To manufacture it, you will need exactly 83 meters of copper wire with a diameter of 2.5 mm. The antenna is a square with a side of 20.7 meters, which is suspended horizontally at a height of 30 feet - this is approximately 9 m. The connecting line is made of 75 Ohm coaxial cable. According to the author, the antenna has a gain of 6 dB relative to the dipole. At 80 meters it has fairly high radiation angles and works well at distances of 700... 800 km. Starting from the 40 meter range, the radiation angles in the vertical plane decrease. Horizontally, the antenna does not have any directional priorities. Its author also suggests using it for mobile-stationary work in the field.
3/4 Long Wire Antenna
Most of its dipole antennas are based on the 3/4L wavelength of each side. We will consider one of them - “Inverted Vee”.
The physical length of the antenna is greater than its resonant frequency; increasing the length to 3/4L expands the antenna's bandwidth compared to a standard dipole and lowers the vertical radiation angles, making the antenna longer-range. In the case of a horizontal arrangement in the form of an angular antenna (half-diamond), it acquires very decent directional properties. All these properties also apply to the antenna made in the form of “INV Vee”. The input impedance of the antenna is reduced and special measures are required to coordinate with the power line. With horizontal suspension and a total length of 3/2L, the antenna has four main and two minor lobes. The author of the antenna (W3FQJ) provides many calculations and diagrams for different dipole arm lengths and suspension catch. According to him, he derived two formulas containing two “magic” numbers that allow one to determine the length of the dipole arm (in feet) and the length of the feeder in relation to the amateur bands:
L (each half) = 738/F (in MHz) (in feet feet),
L (feeder) = 650/F (in MHz) (in feet).
For a frequency of 14.2 MHz,
L (each half) = 738/14.2 = 52 feet (feet),
L (feeder) = 650/F = 45 feet 9 inches.
(Convert to the metric system yourself; the author of the antenna calculates everything in feet). 1 Foot =30.48 cm
Then for a frequency of 14.2 MHz: L (each half) = (738/14.2)* 0.3048 =15.84 meters, L (feeder) = (650/F14.2)* 0.3048 =13.92 meters
P.S. For other selected arm length ratios, the coefficients change.
The 1985 Radio Yearbook published an antenna with a slightly strange name. It is depicted as an ordinary isosceles triangle with a perimeter of 41.4 m and, obviously, therefore did not attract attention. As it turned out later, it was in vain. I just needed a simple multi-band antenna, and I hung it at a low height - about 7 meters. The length of the RK-75 power cable is about 56 m (half-wave repeater).
The measured SWR values practically coincided with those given in the Yearbook. 
Coil L1 is wound on an insulating frame with a diameter of 45 mm and contains 6 turns of PEV-2 wire with a thickness of 2 ... 2 mm. HF transformer T1 is wound with MGShV wire on a ferrite ring 400NN 60x30x15 mm, contains two windings of 12 turns each. The size of the ferrite ring is not critical and is selected based on the power input. The power cable is connected only as shown in the figure; if it is turned on the other way around, the antenna will not work. The antenna does not require adjustment, the main thing is to accurately maintain its geometric dimensions. When operating on the 80 m range, compared to other simple antennas, it loses in transmission - the length is too short. At the reception, the difference is practically not felt. Measurements carried out by G. Bragin’s HF bridge (“R-D” No. 11) showed that we are dealing with a non-resonant antenna.
The frequency response meter shows only the resonance of the power cable. It can be assumed that the result is a fairly universal antenna (from simple ones), has small geometric dimensions and its SWR is practically independent of the height of the suspension. Then it became possible to increase the height of the suspension to 13 meters above the ground. And in this case, the SWR value for all major amateur bands, except for 80 meters, did not exceed 1.4. On the eighty, its value ranged from 3 to 3.5 at the upper frequency of the range, so to match it, a simple antenna tuner is additionally used. Later it was possible to measure SWR on the WARC bands. There the SWR value did not exceed 1.3. The antenna drawing is shown in the figure.
GROUND PLANE at 7 MHz
When operating in low-frequency bands, a vertical antenna has a number of advantages. However, due to its large size, it cannot be installed everywhere. Reducing the antenna height leads to a drop in radiation resistance and an increase in losses. A wire mesh screen and eight radial wires are used as an artificial “ground.” The antenna is powered by a 50-ohm coaxial cable. The SWR of the antenna tuned using a series capacitor was 1.4. Compared to the previously used “Inverted V” antenna, this antenna provided a gain in volume of 1 to 3 points when working with DX.
QST, 1969, N 1 Radio amateur S. Gardner (K6DY/W0ZWK) applied a capacitive load at the end of the “Ground Plane” antenna on the 7 MHz band (see figure), which made it possible to reduce its height to 8 m. The load is a cylinder of wire mesh.
P.S. In addition to QST, a description of this antenna was published in Radio magazine. In the year 1980, while still a novice radio amateur, I manufactured this version of GP. The capacitive load and artificial soil were made from galvanized mesh, fortunately in those days there was plenty of this. Indeed, the antenna outperformed Inv.V. on long routes. But having then installed the classic 10-meter GP, I realized that there was no need to bother making a container on top of the pipe, but it was better to make it two meters longer. The complexity of manufacturing does not pay for the design, not to mention the materials for the manufacture of the antenna.
Antenna DJ4GA
In appearance, it resembles the generatrix of a discone antenna, and its overall dimensions do not exceed the overall dimensions of a conventional half-wave dipole. A comparison of this antenna with a half-wave dipole having the same suspension height showed that it is somewhat inferior to the SHORT-SKIP dipole for short-range communications, but is significantly more effective it for long-distance communications and for communications carried out using earth waves. The described antenna has a larger bandwidth compared to a dipole (by about 20%), which in the range of 40 m reaches 550 kHz (at SWR level up to 2). With appropriate changes in size, the antenna can be used on other bands. The introduction of four notch circuits into the antenna, similar to how it was done in the W3DZZ antenna, makes it possible to implement an effective multi-band antenna. The antenna is powered by a coaxial cable with a characteristic impedance of 50 Ohms.
P.S. I made this antenna. All dimensions were consistent and identical to the drawing. It was installed on the roof of a five-story building. When moving from the triangle of the 80-meter range, located horizontally, on nearby routes the loss was 2-3 points. It was checked during communications with stations of the Far East (R-250 receiving equipment). Won against the triangle by a maximum of one and a half points. When compared with the classic GP, it lost by one and a half points. The equipment used was homemade, UW3DI amplifier 2xGU50.
All-wave amateur antenna
The antenna of a French amateur radio operator is described in the CQ magazine. According to the author of this design, the antenna gives good results when operating on all short-wave amateur bands - 10, 15, 20, 40 and 80 m. It does not require any special careful calculation (except for calculating the length of the dipoles) or precise tuning.
It should be installed immediately so that the maximum directional characteristic is oriented in the direction of the preferential connections. The feeder of such an antenna can be either two-wire, with a characteristic impedance of 72 Ohms, or coaxial, with the same characteristic impedance.
For each band, except for the 40 m band, the antenna has a separate half-wave dipole. On the 40-meter band, a 15-meter dipole works well in such an antenna. All dipoles are tuned to the mid-frequencies of the corresponding amateur bands and are connected in the center in parallel to two short copper wires. The feeder is soldered to the same wires from below.
Three plates of dielectric material are used to insulate the central wires from each other. Holes are made at the ends of the plates for attaching dipole wires. All wire connection points in the antenna are soldered, and the feeder connection point is wrapped with plastic tape to prevent moisture from entering the cable. The length L (m) of each dipole is calculated using the formula L=152/fcp, where fav is the average frequency of the range in MHz. Dipoles are made of copper or bimetallic wire, guy wires are made of wire or rope. Antenna height - any, but not less than 8.5 m.
P.S. It was also installed on the roof of a five-story building; an 80-meter dipole was excluded (the size and configuration of the roof did not allow it). The masts were made of dry pine, butt 10 cm in diameter, height 10 meters. The antenna sheets were made from welding cable. The cable was cut, one core consisting of seven copper wires was taken. Additionally, I twisted it a little to increase density. They showed themselves to be normal, separately suspended dipoles. Quite an acceptable option for work.
Switchable dipoles with active power supply
The antenna with a switchable radiation pattern is a type of two-element linear antennas with active power and is designed to operate in the 7 MHz band. The gain is about 6 dB, the forward-backward ratio is 18 dB, the sideways ratio is 22-25 dB. The beam width at half power level is about 60 degrees. For the 20 m range L1=L2= 20.57 m: L3 = 8.56 m
Bimetal or ant. cord 1.6… 3 mm.
I1 =I2= 14m cable 75 Ohm
I3= 5.64m cable 75 Ohm
I4 =7.08m cable 50 Ohm
I5 = random length 75 ohm cable
K1.1 - HF relay REV-15
As can be seen from Fig. 1, two active vibrators L1 and L2 are located at a distance L3 (phase shift 72 degrees) from each other. The elements are powered out of phase, the total phase shift is 252 degrees. K1 provides switching of the radiation direction by 180 degrees. I3 - phase-shifting loop; I4 - quarter-wave matching section. Tuning the antenna consists of adjusting the dimensions of each element one by one to the minimum SWR with the second element short-circuited through a half-wave repeater 1-1 (1.2). The SWR in the middle of the range does not exceed 1.2, at the edges of the range -1.4. The dimensions of the vibrators are given for a suspension height of 20 m. From a practical point of view, especially when working in competitions, a system consisting of two similar antennas located perpendicular to each other and spaced apart in space has proven itself well. In this case, a switch is placed on the roof, instantaneous switching of the radiation pattern in one of four directions is achieved. One of the options for the location of antennas among typical urban buildings is shown in Fig. 2. This antenna has been used since 1981, has been repeated many times at different QTHs, and has been used to make tens of thousands of QSOs with more than 300 countries around the world.
From the UX2LL website, the original source is “Radio No. 5 page 25 S. Firsov. UA3LD
Beam antenna for 40 meters with a switchable radiation pattern
The antenna, shown schematically in the figure, is made of copper wire or bimetal with a diameter of 3...5 mm. The matching line is made from the same material. Relays from the RSB radio station are used as switching relays. The matcher uses a variable capacitor from a conventional broadcast receiver, carefully protected from moisture. The relay control wires are attached to a nylon stretch cord running along the center line of the antenna. The antenna has a wide radiation pattern (about 60°). The forward-backward radiation ratio is within 23…25 dB. The calculated gain is 8 dB. The antenna was used for a long time at station UK5QBE.
Vladimir Latyshenko (RB5QW) Zaporozhye
P.S. Outside my roof, as an outdoor option, out of interest I conducted an experiment with an antenna made like Inv.V. The rest I learned and performed as in this design. The relay used automotive, four-pin, metal casing. Since I used a 6ST132 battery for power. Equipment TS-450S. One hundred watts. Indeed, the result, as they say, is obvious! When switching to the east, Japanese stations began to be called. VK and ZL, which were somewhat further south in direction, had difficulty making their way through the stations of Japan. I won’t describe the West, everything was booming! The antenna is great! It's a pity there isn't enough space on the roof!
Multiband dipole on WARC bands
The antenna is made of copper wire with a diameter of 2 mm. The insulating spacers are made from 4 mm thick textolite (possibly from wooden planks) on which insulators for external electrical wiring are attached using bolts (MB). The antenna is powered by a coaxial cable type RK 75 of any reasonable length. The lower ends of the insulator strips must be stretched with a nylon cord, then the entire antenna will stretch well and the dipoles will not overlap each other. A number of interesting DX-QSOs were carried out with this antenna from all continents using the UA1FA transceiver with one GU29 without RA.
Antenna DX 2000
Shortwave operators often use vertical antennas. To install such antennas, as a rule, a small free space is required, so for some radio amateurs, especially those living in densely populated urban areas), a vertical antenna is the only opportunity to go on the air on short waves. One of the still little-known vertical antennas operating on all HF bands is DX 2000 antenna. In favorable conditions, the antenna can be used for DX radio communications, but when working with local correspondents (at distances of up to 300 km), it is inferior to a dipole. As is known, a vertical antenna installed above a well-conducting surface has almost ideal “DX properties”, i.e. very low beam angle. This does not require a high mast. Multi-band vertical antennas, as a rule, are designed with barrier filters (ladders) and they work in almost the same way as single-band quarter-wave antennas. Broadband vertical antennas used in professional HF radio communications have not found much response in HF amateur radio, but they have interesting properties.
On 
The figure shows the most popular vertical antennas among radio amateurs - a quarter-wave emitter, an electrically extended vertical emitter and a vertical emitter with ladders. Example of the so-called exponential antenna is shown on the right. Such a volumetric antenna has good efficiency in the frequency band from 3.5 to 10 MHz and quite satisfactory matching (SWR<3) вплоть до верхней границы КВ диапазона (30 МГц). Очевидно, что КСВ = 2 - 3 для транзисторного передатчика очень нежелателен, но, учитывая широкое распространение в настоящее время антенных тюнеров (часто автоматических и встроенных в трансивер), с высоким КСВ в фидере антенны можно мириться. Для лампового усилителя, имеющего в выходном каскаде П - контур, как правило, КСВ = 2 - 3 
does not pose a problem. The DX 2000 vertical antenna is a kind of hybrid of a narrowband quarter-wave antenna (Ground plane), tuned to resonance in some amateur bands, and a wideband exponential antenna. The antenna is based on a tubular emitter about 6 m long. It is assembled from aluminum pipes with a diameter of 35 and 20 mm, inserted into each other and forming a quarter-wave emitter with a frequency of approximately 7 MHz. Tuning the antenna to a frequency of 3.6 MHz is ensured by a 75 μH inductor connected in series, to which a thin aluminum 
tube 1.9 m long. The matching device uses a 10 μH inductor, to the taps of which a cable is connected. In addition, 4 side emitters made of copper wire in PVC insulation with a length of 2480, 3500, 5000 and 5390 mm are connected to the coil. For fastening, the emitters are extended with nylon cords, the ends of which converge under a 75 μH coil. When operating in the 80 m range, grounding or counterweights are required, at least for protection from lightning. To do this, you can bury several galvanized strips deep into the ground. When installing an antenna on the roof of a house, it is very difficult to find some kind of “ground” for HF. Even a well-made grounding on the roof does not have zero potential relative to the ground, so it is better to use metal ones for grounding on a concrete roof.
structures with a large surface area. In the matching device used, the grounding is connected to the terminal of the coil, in which the inductance up to the tap where the cable braid is connected is 2.2 μH. Such a small inductance is not sufficient to suppress the currents flowing through the outer side of the braid of the coaxial cable, so a shut-off choke should be made by coiling about 5 m of the cable into a coil with a diameter of 30 cm. 
For effective operation of any quarter-wave vertical antenna (including the DX 2000), it is imperative to manufacture a system of quarter-wave counterweights. The DX 2000 antenna was manufactured at the radio station SP3PML (Military Club of Shortwave and Radio Amateurs PZK).
A sketch of the antenna design is shown in the figure. The emitter was made of durable duralumin pipes with a diameter of 30 and 20 mm. The guy wires used to fasten the copper emitter wires must be resistant to both stretching and weather conditions. The diameter of copper wires should be no more than 3 mm (to limit their own weight), and it is advisable to use insulated wires, which will ensure resistance to weather conditions. To fix the antenna, you should use strong insulating guys that do not stretch when weather conditions change. Spacers for copper wires of emitters should be made of dielectric (for example, PVC pipe with a diameter of 28 mm), but to increase rigidity they can be made of a wooden block or other material that is as light as possible. The entire antenna structure is mounted on a steel pipe no longer than 1.5 m, previously rigidly attached to the base (roof), for example, with steel guys. The antenna cable can be connected through a connector, which must be electrically isolated from the rest of the structure.
To tune the antenna and match its impedance with the characteristic impedance of the coaxial cable, inductance coils of 75 μH (node A) and 10 μH (node B) are used. The antenna is tuned to the required sections of the HF bands by selecting the inductance of the coils and the position of the taps. The antenna installation location should be free from other structures, preferably at a distance of 10-12 m, then the influence of these structures on the electrical characteristics of the antenna is small.
Addition to the article:
If the antenna is installed on the roof of an apartment building, its installation height should be more than two meters from the roof to the counterweights (for safety reasons). I categorically do not recommend connecting the antenna grounding to the general grounding of a residential building or to any fittings that make up the roof structure (to avoid huge mutual interference). It is better to use individual grounding, located in the basement of the house. It should be stretched in the communication niches of the building or in a separate pipe pinned to the wall from bottom to top. It is possible to use a lightning arrester.
V. Bazhenov UA4CGR
Method for accurately calculating cable length
Many radio amateurs use 1/4 wave and 1/2 wave coaxial lines. They are needed as impedance repeater resistance transformers, phase delay lines for actively powered antennas, etc. The simplest method, but also the most inaccurate, is the method of multiplying part of the wavelength by coefficient is 0.66, but it is not always suitable when it is necessary to be quite accurate 
calculate the cable length, for example 152.2 degrees.
Such accuracy is necessary for antennas with active power supply, where the quality of the antenna’s operation depends on the phasing accuracy.
The coefficient 0.66 is taken as average, because for the same dielectric, the dielectric constant can deviate noticeably, and therefore the coefficient will also deviate. 0.66. I would like to suggest the method described by ON4UN.
It is simple, but requires equipment (a transceiver or generator with a digital scale, a good SWR meter and a load equivalent of 50 or 75 Ohms depending on the Z cable) Fig. 1. From the figure you can understand how this method works.
The cable from which it is planned to make the required segment must be short-circuited at the end.
Next, let's look at a simple formula. Let's say we need a segment of 73 degrees to operate at a frequency of 7.05 MHz. Then our cable section will be exactly 90 degrees at a frequency of 7.05 x (90/73) = 8.691 MHz. This means that when tuning the transceiver by frequency, at 8.691 MHz our SWR meter must indicate the minimum SWR because at this frequency the cable length will be 90 degrees, and for a frequency of 7.05 MHz it will be exactly 73 degrees. Once shorted, it will invert the short circuit into infinite resistance and thus will have no effect on the SWR meter reading at 8.691 MHz. For these measurements, you need either a sufficiently sensitive SWR meter, or a sufficiently powerful load equivalent, because You will have to increase the power of the transceiver for reliable operation of the SWR meter if it does not have enough power for normal operation. This method gives very high measurement accuracy, which is limited by the accuracy of the SWR meter and the accuracy of the transceiver scale. For measurements, you can also use the VA1 antenna analyzer, which I mentioned earlier. An open cable will indicate zero impedance at the calculated frequency. It's very convenient and fast. I think this method will be very useful for radio amateurs.
Alexander Barsky (VAZTTTT), vаЗ[email protected]
Asymmetrical GP antenna
The antenna is (Fig. 1) nothing more than a “groundplane” with an elongated vertical emitter 6.7 m high and four counterweights, each 3.4 m long. A wideband impedance transformer (4:1) is installed at the power point.
At first glance, the indicated antenna dimensions may seem incorrect. However, adding the length of the emitter (6.7 m) and the counterweight (3.4 m), we are convinced that the total length of the antenna is 10.1 m. Taking into account the shortening factor, this is Lambda / 2 for the range of 14 MHz and 1 Lambda for 28 MHz.
The resistance transformer (Fig. 2) is made according to the generally accepted method on a ferrite ring from the OS of a black and white TV and contains 2 × 7 turns. It is installed at the point where the antenna input impedance is about 300 Ohms (a similar excitation principle is used in modern modifications of the Windom antenna).
The average vertical diameter is 35 mm. To achieve resonance at the required frequency and more precise matching with the feeder, the size and position of the counterweights can be changed within small limits. In the author's version, the antenna has resonance at frequencies of about 14.1 and 28.4 MHz (SWR = 1.1 and 1.3, respectively). If desired, by approximately doubling the dimensions shown in Fig. 1, you can achieve antenna operation in the 7 MHz range. Unfortunately, in this case the radiation angle in the 28 MHz range will be “damaged”. However, by using a U-shaped matching device installed near the transceiver, you can use the author’s version of the antenna to operate in the 7 MHz range (though with a loss of 1.5...2 points relative to the half-wave dipole), as well as in the 18, 21 bands , 24 and 27 MHz. Over five years of operation, the antenna showed good results, especially in the 10-meter range.
Shortwave operators often have difficulty installing full-size antennas to operate on low-frequency HF bands. One of the possible versions of a shortened (about half) dipole for the 160 m range is shown in the figure. The total length of each half of the emitter is about 60 m.
They are folded in three, as shown schematically in Figure (a) and are held in this position by two end insulators (c) and several intermediate insulators (b). These insulators, as well as a similar central one, are made of a non-hygroscopic dielectric material approximately 5 mm thick. The distance between adjacent conductors of the antenna fabric is 250 mm.
A coaxial cable with a characteristic impedance of 50 Ohms is used as a feeder. The antenna is tuned to the average frequency of the amateur band (or the required section of it - for example, telegraph) by moving the two jumpers connecting its outer conductors (they are shown as dashed lines in the figure) and maintaining the symmetry of the dipole. The jumpers must not have electrical contact with the center conductor of the antenna. With the dimensions indicated in the figure, a resonant frequency of 1835 kHz was achieved by installing jumpers at a distance of 1.8 m from the ends of the web. The standing wave coefficient at the resonant frequency is 1.1. There is no data on its dependence on frequency (i.e., the antenna bandwidth) in the article.
Antenna for 28 and 144 MHz
For sufficiently efficient operation in the 28 and 144 MHz bands, rotating directional antennas are required. However, it is usually not possible to use two separate antennas of this type on a radio station. Therefore, the author made an attempt to combine antennas of both ranges, making them in the form of a single structure.
The dual-band antenna is a double “square” at 28 MHz, on the carrier beam of which a nine-element wave channel at 144 MHz is mounted (Fig. 1 and 2). As practice has shown, their mutual influence on each other is insignificant. The influence of the wave channel is compensated by a slight decrease in the perimeters of the “square” frames. “Square”, in my opinion, improves the parameters of the wave channel, increasing the gain and suppression of reverse radiation. The antennas are powered using feeders from a 75-ohm coaxial cable. The “square” feeder is included in the gap in the lower corner of the vibrator frame (in Fig. 1 on the left). A slight asymmetry with such inclusion causes only a slight skew of the radiation pattern in the horizontal plane and does not affect other parameters.
The wave channel feeder is connected through a balancing U-elbow (Fig. 3). As measurements have shown, the SWR in the feeders of both antennas does not exceed 1.1. The antenna mast can be made of steel or duralumin pipe with a diameter of 35-50 mm. A gearbox combined with a reversible motor is attached to the mast. A “square” traverse made of pine wood is screwed to the gearbox flange using two metal plates with M5 bolts. The cross section is 40x40 mm. At its ends there are crosspieces, which are supported by eight “square” wooden poles with a diameter of 15-20 mm. The frames are made of bare copper wire with a diameter of 2 mm (PEV-2 wire 1.5 - 2 mm can be used). The perimeter of the reflector frame is 1120 cm, the vibrator 1056 cm. The wave channel can be made of copper or brass tubes or rods. Its traverse is secured to the “square” traverse using two brackets. The antenna settings have no special features.
If the recommended dimensions are exactly repeated, it may not be needed. The antennas have shown good results over several years of operation at the RA3XAQ radio station. A lot of DX communications were carried out on 144 MHz - with Bryansk, Moscow, Ryazan, Smolensk, Lipetsk, Vladimir. On 28 MHz, a total of more than 3.5 thousand QSOs were installed, among them - from VP8, CX, LU, VK, KW6, ZD9, etc. The design of the dual-band antenna was repeated three times by radio amateurs of Kaluga (RA3XAC, RA3XAS, RA3XCA) and also received positive ratings .
P.S. In the eighties of the last century there was exactly such an antenna. Mainly made for working through low-orbit satellites... RS-10, RS-13, RS-15. I used UW3DI with Zhutyaevsky transverter, and R-250 for reception. Everything worked out well with ten watts. The squares on the ten worked well, there were a lot of VK, ZL, JA, etc... And the passage was wonderful then!
Extended version of W3DZZ
The antenna shown in the figure is an extended version of the well-known W3DZZ antenna, adapted to operate on the bands 160, 80, 40 and 10 m. To suspend its web, a “span” of about 67 m is required.
The power cable can have a characteristic impedance of 50 or 75 Ohms. The coils are wound on nylon frames (water pipes) with a diameter of 25 mm using PEV-2 wire 1.0 turn to turn (38 in total). Capacitors C1 and C2 are made up of four series-connected KSO-G capacitors with a capacity of 470 pF (5%) for an operating voltage of 500V. Each chain of capacitors is placed inside the coil and sealed with sealant.
To mount the capacitors, you can also use a fiberglass plate with foil “spots” to which the leads are soldered. The circuits are connected to the antenna sheet as shown in the figure. When using the above elements, there were no failures when the antenna operated in conjunction with a radio station of the first category. The antenna, suspended between two nine-story buildings and fed through an RK-75-4-11 cable about 45 m long, provided an SWR of no more than 1.5 at frequencies of 1840 and 3580 kHz and no more than 2 in the range 7...7.1 and 28, 2…28.7 MHz. The resonant frequency of the plug filters L1C1 and L2C2, measured by the GIR before connecting to the antenna, was equal to 3580 kHz.
W3DZZ with coaxial cable ladders
This design is based on the ideology of the W3DZZ antenna, but the barrier circuit (ladder) at 7 MHz is made of coaxial cable. The antenna drawing is shown in Fig. 1, and the design of the coaxial ladder is shown in Fig. 2. The vertical end parts of the 40-meter dipole sheet have a size of 5...10 cm and are used to tune the antenna to the required part of the range. The ladders are made of 50 or 75-ohm cable 1.8 m long, laid in a twisted coil with a diameter of 10 cm , as shown in Fig. 2. The antenna is powered by a coaxial cable through a balun made of six ferrite rings placed on the cable near the power points.
P.S. No adjustments were required during the manufacture of the antenna as such. Particular attention was paid to sealing the ends of the ladders. First, I filled the ends with electrical wax, or paraffin from a regular candle, then covered it with silicone sealant. Which is sold in auto stores. The best quality sealant is gray.
Antenna "Fuchs" for 40 m range
Luc Pistorius (F6BQU)
Translation by Nikolay Bolshakov (RA3TOX), E-mail: boni(doggie)atnn.ru
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A variant of the matching device shown in Fig. 1 differs in that fine adjustment of the length of the antenna web is carried out from the “nearby” end (next to the matching device). This is really very convenient, since it is impossible to set the exact length of the antenna fabric in advance. The environment will do its job and eventually inevitably change the resonant frequency of the antenna system. In this design, the antenna is tuned to resonance using a piece of wire about 1 meter long. This piece is located next to you and is convenient for adjusting the antenna to resonance. In the author's version, the antenna is installed on a garden plot. One end of the wire goes into the attic, the second is attached to a pole 8 meters high, installed in the depths of the garden. The length of the antenna wire is 19 m. In the attic, the end of the antenna is connected by a piece 2 meters long to a matching device. Total - the total length of the antenna fabric is 21 m. A counterweight 1 m long is located together with the control system in the attic of the house. Thus, the entire structure is under the roof and, therefore, protected from the elements. 
For the 7 MHz range, the device elements have the following ratings:
Cv1 = Cv2 = 150 pf;
L1 - 18 turns of copper wire with a diameter of 1.5 mm on a frame with a diameter of 30 mm (PVC pipe);
L1 - 25 turns of copper wire with a diameter of 1 mm on a frame with a diameter of 40 mm (PVC pipe); We tune the antenna to a minimum SWR. First, we set the minimum SWR with capacitor Cv1, then we try to reduce the SWR with capacitor Cv2 and finally make the adjustment by selecting the length of the compensating segment (counterweight). Initially, we select the length of the antenna wire a little more than half a wave and then compensate for it with a counterweight. The Fuchs antenna is a familiar stranger. An article with this title talked about this antenna and two options for matching devices for it, proposed by the French radio amateur Luc Pistorius (F6BQU).
Field antenna VP2E
The VP2E (Vertically Polarized 2-Element) antenna is a combination of two half-wave emitters, due to which it has a two-way symmetrical radiation pattern with unsharp minima. The antenna has vertical (see name) radiation polarization and a radiation pattern pressed to the ground in the vertical plane. The antenna provides a gain of +3 dB compared to an omnidirectional emitter in the direction of radiation maxima and a suppression of about -14 dB in the dips of the pattern.
A single-band version of the antenna is shown in Fig. 1, its dimensions are summarized in the table.
Element Length in L Length for the 80th range I1 = I2 0.492 39 m I3 0.139 11 m h1 0.18 15 m h2 0.03 2.3 m The radiation pattern is shown in Fig. 2. 
For comparison, the radiation patterns of a vertical emitter and a half-wave dipole are superimposed on it. Figure 3 shows a five-band version of the VP2E antenna. Its resistance at the power point is about 360 Ohms. When the antenna was powered via a cable with a resistance of 75 Ohms through a 4:1 matching transformer on a ferrite core, the SWR was 1.2 on the 80 m range; 40 m - 1.1; 20 m - 1.0; 15 m - 2.5; 10 m - 1.5. Probably, when powered over a two-wire line through an antenna tuner, better matching can be achieved.
"Secret" antenna
In this case, the vertical “legs” are 1/4 long, and the horizontal part is 1/2 long. The result is two vertical quarter-wave emitters, powered in antiphase.
An important advantage of this antenna is that the radiation resistance is about 50 Ohms.
It is energized at the bend point, with the central core of the cable connected to the horizontal part, and the braid to the vertical part. Before making an antenna for the 80m band, I decided to prototype it at a frequency of 24.9 MHz, because I had an inclined dipole for this frequency and therefore had something to compare with. At first I listened to the NCDXF beacons and did not notice a difference: somewhere better, somewhere worse. When UA9OC, located 5 km away, gave a weak tuning signal, all doubts disappeared: in the direction perpendicular to the canvas, the U-shaped antenna has an advantage of at least 4 dB relative to the dipole. Then there was an antenna for 40 m and, finally, for 80 m. Despite the simplicity of the design (see Fig. 1), hooking it to the tops of poplar trees in the yard was not easy.
I had to make a halberd with a bowstring from steel millimeter wire and an arrow from a 6 mm duralumin tube 70 cm long with a weight in the bow and a rubber tip (just in case!). At the rear end of the arrow, I secured a 0.3 mm fishing line with a cork, and with it I launched the arrow to the top of the tree. Using a thin fishing line, I tightened another, 1.2 mm, with which I suspended the antenna from a 1.5 mm wire.
One end turned out to be too low, the kids would certainly pull it (it’s a shared yard!), so I had to bend it and let the tail run horizontally at a height of 3 m from the ground. For power supply I used a 50-ohm cable with a 3 mm diameter (insulation) for lightness and as less noticeable. Tuning consists of adjusting the length, because surrounding objects and the ground slightly lower the calculated frequency. We must remember that we shorten the end closest to the feeder by D L = (D F/300,000)/4 m, and the far end by three times as much.
It is assumed that the diagram in the vertical plane is flattened at the top, which manifests itself in the effect of “leveling” the signal strength from far and near stations. In the horizontal plane, the diagram is elongated in the direction perpendicular to the antenna surface. It is difficult to find trees 21 meters high (for the 80 m range), so you have to bend the lower ends and run them horizontally, which reduces the antenna resistance. Apparently, such an antenna is inferior to a full-size GP, since the radiation pattern is not circular, but it does not need counterweights! Quite pleased with the results. At least this antenna seemed much better to me than the Inverted-V that preceded it. Well, for “Field Day” and for not very “cool” DX-pedition on low-frequency ranges, it probably has no equal.
From the UX2LL website
Compact 80 meter loop antenna
Many radio amateurs have country houses, and often the small size of the plot on which the house is located does not allow them to have a sufficiently effective HF antenna.
For DX, it is preferable for the antenna to radiate at small angles to the horizon. In addition, its designs should be easily repeatable.
The proposed antenna (Fig. 1) has a radiation pattern similar to that of a vertical quarter-wave emitter. Its maximum radiation in the vertical plane occurs at an angle of 25 degrees to the horizontal. Also, one of the advantages of this antenna is its simplicity of design, since for its installation it is enough to use a twelve-meter metal mast. The antenna fabric can be made of P-274 field telephone wire. Power is supplied to the middle of any of the vertically located sides. If the specified dimensions are observed, its input impedance is in the range of 40...55 Ohms.
Practical tests of the antenna have shown that it provides a gain in signal level for remote correspondents on routes of 3000...6000 km in comparison with antennas such as the half-wave Inverted Vee? horizontal Delta-Loor" and quarter-wave GP with two radials. The difference in signal level when compared with a half-wave dipole antenna on paths over 3000 km reaches 1 point (6 dB). The measured SWR was 1.3-1.5 over the range.
RV0APS Dmitry SHABANOV Krasnoyarsk
Receiving antenna 1.8 - 30 MHz
When going outdoors, many people take various radios with them. There are plenty of them available now. Various brands of Grundig satellite, Degen, Tecsun... As a rule, a piece of wire is used for the antenna, which in principle is quite sufficient. The antenna shown in the figure is a type of ABC antenna, and has a radiation pattern. When received on a Degen DE1103 radio receiver, it showed its selective qualities, the signal to the correspondent when directed by her increased by 1-2 points.
Shortened dipole 160 meters
A regular dipole is perhaps one of the simplest but most effective antennas. However, for the 160-meter range, the length of the radiating part of the dipole exceeds 80 m, which usually causes difficulties in its installation. One of the possible ways to overcome them is to introduce shortening coils into the emitter. Shortening the antenna usually leads to a decrease in its efficiency, but sometimes the radio amateur is forced to make such a compromise. A possible design of a dipole with extension coils for a range of 160 meters is shown in Fig. 8. The total dimensions of the antenna do not exceed the dimensions of a conventional dipole for a range of 80 meters. Moreover, such an antenna can easily be converted into a dual-band antenna by adding relays that would close both coils. In this case, the antenna turns into a regular dipole for a range of 80 meters. If there is no need to work on two bands, and the location for installing the antenna makes it possible to use a dipole with a length greater than 42 m, then it is advisable to use an antenna with the maximum possible length.
The inductance of the extension coil in this case is calculated using the formula: Here L is the inductance of the coil, μH; l is the length of half of the radiating part, m; d - antenna wire diameter, m; f - operating frequency, MHz. Using the same formula, the inductance of the coil is also calculated if the location for installing the antenna is less than 42 m. However, it should be borne in mind that when the antenna is significantly shortened, its input impedance noticeably decreases, which creates difficulties in matching the antenna with the feeder, and this, in particular, further worsens its effectiveness.
Modification of antenna DL1BU
For a year, my radio station of the second category has been using a simple antenna (see Fig. 1), which is a modification of the DL1BU antenna. It operates in the ranges of 40, 20 and 10 m, does not require the use of a symmetrical feeder, is well coordinated, and is easy to manufacture. A transformer on a ferrite ring is used as a matching and balancing element. grade VCh-50 with a cross section of 2.0 sq.cm. The number of turns of its primary winding is 15, the secondary winding is 30, the wire is PEV-2. with a diameter of 1 mm. When using a ring of a different section, you need to reselect the number of turns using the diagram shown in Fig. 2. As a result of selection, it is necessary to obtain the minimum SWR in the range of 10 meters. The antenna made by the author has an SWR of 1.1 at 40 m, 1.3 at 20 m and 1.8 at 10 m.
V. KONONOV (UY5VI) Donetsk
P.S. In the manufacture of the design, I used a U-shaped core from a TV line transformer, without changing the turns, I obtained a similar SWR value, with the exception of the 10-meter range. The best SWR was 2.0, and naturally varied with frequency.
Short antenna for 160 meters
The antenna is an asymmetrical dipole, which is powered through a matching transformer by a coaxial cable with a characteristic impedance of 75 Ohms. The antenna is best made of bimetal with a diameter of 2...3 mm - the antenna cord and copper wire are stretched over time, and the antenna is detuned.
The matching transformer T can be made on a ring magnetic core with a cross section of 0.5...1 cm2 made of ferrite with an initial magnetic permeability of 100...600 (preferably NN grade). In principle, you can also use magnetic cores from fuel assemblies of old televisions, which are made of HH600 material. The transformer (it must have a transformation ratio of 1:4) is wound into two wires, and the terminals of windings A and B (the indices “n” and “k” indicate the beginning and end of the winding, respectively) are connected, as shown in Fig. 1b.
For the transformer windings, it is best to use stranded installation wire, but regular PEV-2 can also be used. Winding is carried out with two wires at once, laying them tightly, turn to turn, along the inner surface of the magnetic circuit. Overlapping of wires is not allowed. The coils are placed at even intervals along the outer surface of the ring. The exact number of double turns is unimportant - it can be in the range of 8...15. The manufactured transformer is placed in a plastic cup of the appropriate size (Fig. 1c, item 1) and filled with epoxy resin. In the uncured resin, in the center of the transformer 2, a screw 5 with a length of 5...6 mm is sunk head down. It is used to fasten the transformer and coaxial cable (using a clip 4) to the textolite plate 3. This plate, 80 mm long, 50 mm wide and 5...8 mm thick, forms the central insulator of the antenna - the antenna sheets are also attached to it. The antenna is tuned to a frequency of 3550 kHz by selecting the minimum SWR of the length of each antenna blade (in Fig. 1 they are indicated with some margin). The shoulders should be shortened gradually by about 10...15 cm at a time. After completing the setup, all connections are carefully soldered and then filled with paraffin. Be sure to cover the exposed part of the coaxial cable braid with paraffin. As practice has shown, paraffin protects antenna parts from moisture better than other sealants. Paraffin coating does not age in air. The antenna made by the author had a bandwidth at SWR = 1.5 on the 160 m range - 25 kHz, on the 80 m range - about 50 kHz, on the 40 m range - about 100 kHz, on the 20 m range - about 200 kHz. On the 15 m range, the SWR was within 2...3.5, and on the 10 m range - within 1.5...2.8.
DOSAAF TsRK laboratory. 1974
Automotive HF antenna DL1FDN
In the summer of 2002, despite poor communication conditions on the 80-meter band, I made a QSO with Dietmar, DL1FDN/m, and was pleasantly surprised by the fact that my correspondent was working from a moving car. Intrigued, I inquired about the output power of his transmitter and the design of the antenna . Dietmar. DL1FDN/m, willingly shared information about his homemade car antenna and kindly allowed me to talk about it. The information contained in this note was recorded during our QSO. Apparently his antenna actually works! Dietmar uses an antenna system, the design of which is shown in the figure. The system includes an emitter, an extension coil and a matching device (antenna tuner). The emitter is made of a copper-plated steel pipe 2 m long, installed on an insulator. The extension coil L1 is wound turn to turn. Its winding data for the 160 and 80 m ranges are given in the table . For operation in the 40 m range, coil L1 contains 18 turns, wound with 02 mm wire on a 0100 mm frame. In the ranges of 20, 17, 15, 12 and 10 m, part of the coil turns of the 40 m range is used. The taps on these ranges are selected experimentally. The matching device is an LC circuit consisting of a variable inductance coil L2, which has a maximum inductance of 27 μH (it is advisable not to use a ball variometer). The variable capacitor C1 must have a maximum capacity of 1500...2000 pF. With a transmitter power of 200 W (this is exactly the power the DL1FDN/m uses) 
the gap between the plates of this capacitor must be at least 1 mm. Capacitors C2, SZ - K15U, but at the specified power you can use KSO-14 or similar.
S1 - ceramic biscuit switch. The antenna is tuned at a specific frequency according to the minimum readings of the SWR meter. The cable connecting the matching device to the SWR meter and transceiver has a characteristic impedance of 50 ohms, and the SWR meter is calibrated at a 50 ohm equivalent antenna.
If the transmitter output impedance is 75 ohms, a 75 ohm coaxial cable should be used, and the SWR meter should be “balanced” on the equivalent of a 75 ohm antenna. Using the antenna system described and operating from a moving vehicle, DL1FDN has made many interesting radio contacts on the 80 meter band, including QSOs with other continents.
I. Podgorny (EW1MM)
Compact HF antenna
Small-sized loop antennas (the perimeter of the frame is much smaller than the wavelength) are used in the HF bands mainly only as receiving antennas. Meanwhile, with the appropriate design, they can be successfully used at amateur radio stations and as transmitters. Such an antenna has a number of important advantages: Firstly, its quality factor is at least 200, which can significantly reduce interference from stations operating in neighboring frequencies. The antenna’s small bandwidth naturally necessitates its adjustment even within the same amateur band. Secondly, a small-sized antenna can operate in a wide range of frequencies (frequency overlap reaches 10!). And finally, it has two deep minima at small radiation angles (the radiation pattern is a “figure of eight”). This allows you to rotate the frame (which is not difficult to do given its small dimensions) to effectively suppress interference coming from specific directions. The antenna is a frame (one turn), which is tuned to the operating frequency with a variable capacitor - KPE. The shape of the coil is not important and can be any, but for design reasons, as a rule, frames in the form of a square are used. The operating frequency range of the antenna depends on the size of the frame. The minimum operating wavelength is approximately 4L (L is the perimeter of the frame). The frequency overlap is determined by the ratio of the maximum and minimum values of the KPI capacitance. 
When using conventional capacitors, the frequency overlap of a loop antenna is approximately 4, with vacuum capacitors - up to 10. With a transmitter output power of 100 W, the currents in the loop reach tens of amperes, therefore, to obtain acceptable values of efficiency, the antenna must be made of copper or brass pipes fairly large diameter (approximately 25 mm). The connections on the screws must provide reliable electrical contact, eliminating the possibility of its deterioration due to the appearance of a film of oxides or rust. It is best to solder all connections. A variant of a compact loop antenna designed for operation in the amateur bands 3.5-14 MHz.
A schematic drawing of the entire antenna is shown in Figure 1. In Fig. Figure 2 shows the design of a communication loop with an antenna. The frame itself is made of four copper pipes with a length of 1000 and a diameter of 25 mm. A control unit is included in the lower corner of the frame - it is placed in a box that excludes exposure to atmospheric moisture and precipitation. This KPI, with a transmitter output power of 100 W, must be designed for an operating voltage of 3 kV. The antenna is powered by a coaxial cable with a characteristic impedance of 50 Ohms, at the end of which a communication loop is made. The upper section of the loop in Figure 2 with the braid removed to a length of about 25 mm must be protected from moisture, i.e. some kind of compound. The loop is securely attached to the frame in its upper corner. The antenna is installed on a mast about 2000 mm high made of insulating material. A copy of the antenna made by the author had an operating frequency range of 3.4...15.2 MHz. The standing wave ratio was 2 at 3.5 MHz and 1.5 at 7 and 14 MHz. Comparing it with full-size dipoles installed at the same height showed that in the range of 14 MHz both antennas are equivalent, at 7 MHz the signal level of the loop antenna is 3 dB less, and at 3.5 MHz - by 9 dB. These results were obtained for large radiation angles. For such radiation angles when communicating over a distance of up to 1600 km, the antenna had an almost circular radiation pattern, but also effectively suppressed local interference with its appropriate orientation, which is especially important for those radio amateurs where the level of interference is high. A typical antenna bandwidth is 20 kHz.
Yu. Pogreban, (UA9XEX)
Yagi antenna 2 elements for 3 bands
This is an excellent antenna for field conditions and for working from home. The SWR on all three bands (14, 21, 28) ranges from 1.00 to 1.5. The main advantage of the antenna is its ease of installation - just a few minutes. We install any mast ~12 meters high. At the top there is a block through which a nylon cable is passed. 
The cable is tied to the antenna and it can be raised or lowered instantly. In hiking conditions, this is important, since the weather can change greatly. Removing the antenna is a matter of a few seconds.
Next, only one mast is needed to install the antenna. In a horizontal position, the antenna radiates at large angles to the horizon. If the antenna plane is placed at an angle to the horizon, then the main radiation begins to be pressed toward the ground and the more vertically the antenna is suspended, the more vertically it is suspended. That is, one end is at the top of the mast, and the other is attached to a peg on the ground. (See photo). The closer the peg is to the mast, the more vertical it will be and the closer the vertical radiation angle will be pressed to the horizon. Like all antennas, it radiates in the direction opposite to the reflector. If you move the antenna around the mast, you can change the direction of its radiation. Since the antenna is attached, as can be seen from the figure, at two points, by turning it 180 degrees, you can very quickly change the direction of its radiation to the opposite.
During manufacturing, it is necessary to maintain the dimensions as shown in the figure. We first made it with one reflector - at 14 MHz and it was in the high-frequency part of the 20 meter range.
After adding reflectors at 21 and 28 MHz, it began to resonate in the high-frequency part of the telegraph sections, which made it possible to conduct communications in both CW and SSB sections. The resonance curves are flat and the SWR at the edges is no more than 1.5. We call this antenna Hammock among ourselves. By the way, in the original antenna, Marcus, like the hammocks, had two wooden blocks of 50x50 mm, between which the elements were stretched. We use fiberglass rods, which makes the antenna much lighter. The antenna elements are made of antenna cable with a diameter of 4 mm. Spacers between the vibrators are made of plexiglass. If you have questions, write to: [email protected]
Antenna “Square” with one element at 14 MHz
In one of his books in the late 80s of the twentieth century, W6SAI, Bill Orr proposed a simple antenna - 1 element square, which was installed vertically on one mast. The W6SAI antenna was made with the addition of an RF choke. The square is made for a range of 20 meters (Fig. 1) and is installed vertically on one mast. In continuation of the last bend of the 10-meter army telescope, a fifty centimeter piece of fiberglass is inserted, in shape no different from the upper bend of the telescope, with a hole at the top, which is the upper insulator. The result is a square with a corner at the top, a corner at the bottom and two corners with stretch marks on the sides.
From an efficiency point of view, this is the most advantageous option for locating the antenna, which is low above the ground. The watering point turned out to be about 2 meters from the underlying surface. The cable connection unit is a piece of thick fiberglass 100x100 mm, which is attached to the mast and serves as an insulator.
The perimeter of the square is equal to 1 wavelength and is calculated by the formula: Lм=306.3F mHz. For a frequency of 14.178 MHz. (Lm=306.3.178) the perimeter will be equal to 21.6 m, i.e. side of the square = 5.4 m. Power supply from the bottom corner with a 75 ohm cable 3.49 meters long, i.e. 0.25 wavelength. This piece of cable is a quarter-wave transformer, transforming Rin. antennas are about 120 Ohms, depending on the objects surrounding the antenna, into a resistance close to 50 Ohms. (46.87 ohms). Most of the 75 Ohm cable is located strictly vertically along the mast. Next, through the RF connector there is a main transmission line of a 50 Ohm cable with a length equal to an integer number of half-waves. In my case, this is a segment of 27.93 m, which is a half-wave repeater. This power supply method is well suited for 50 ohm equipment, which today in most cases corresponds to R out. Silo transceivers and the nominal output impedance of power amplifiers (transceivers) with a P-circuit at the output.
When calculating the cable length, you should remember the shortening factor of 0.66-0.68, depending on the type of plastic insulation of the cable. With the same 50 ohm cable, next to the mentioned RF connector, an RF choke is wound. His data: 8-10 turns on a 150mm mandrel. Winding turn to turn. For antennas for low frequency ranges - 10 turns on a 250 mm mandrel. The RF choke eliminates the curvature of the antenna radiation pattern and is a shut-off choke for RF currents moving along the cable braid in the direction of the transmitter. The antenna bandwidth is about 350-400 kHz. with SWR close to unity. Outside the bandwidth, the SWR increases greatly. The antenna polarization is horizontal. The guy wires are made of wire with a diameter of 1.8 mm. broken by insulators at least every 1-2 meters.
If we change the feed point of the square by feeding it from the side, the result is vertical polarization, which is more preferable for DX. Use the same cable as for horizontal polarization, i.e. a quarter-wave section of 75 Ohm cable goes to the frame (the central core of the cable is connected to the upper half of the square, and the braid to the bottom), and then a 50 Ohm cable, a multiple of half-wave. The resonant frequency of the frame when changing the power point will go up by about 200 kHz. (at 14.4 MHz), so the frame will have to be lengthened somewhat. An extension wire, a cable of approximately 0.6-0.8 meters, can be inserted into the lower corner of the frame (at the former antenna power point). To do this, you need to use a piece of two-wire line about 30-40 cm.
Antenna with capacitive load for 160 meters
According to reviews from operators I met on air, they mainly use an 18-meter structure. Of course, there are enthusiasts of the 160-meter range who have pins with larger sizes, but this is probably acceptable somewhere in rural areas. I personally met a radio amateur from Ukraine who used this 21.5-meter-high design. When comparing transmission, the difference between this antenna and the dipole was 2 points, in favor of the pin! According to him, at longer distances the antenna behaves wonderfully, to the point that the correspondent can’t be heard on the dipole, and the probe pulls out a distant QSO! He used a sprinkler, duralumin, thin-walled pipe with a diameter of 160 millimeters. At the joints I covered it with a bandage made from the same pipes. Fastened with rivets (rivet gun). According to him, during the lifting, the structure held up without question. It is not concreted, just covered with earth. In addition to capacitive loads, also used as guy wires, there are two more sets of guy wires. Unfortunately, I forgot the call sign of this radio amateur, and I cannot refer to it correctly!
Receiving antenna T2FD for Degen 1103
This weekend I built the T2FD receiving antenna. And... I was very pleased with the results... The central pipe is made of polypropylene - gray, with a diameter of 50 mm. Used in plumbing under drains. Inside there is a transformer on “binoculars” (using EW2CC technology) and a load resistance of 630 Ohms (suitable from 400 to 600 Ohms). Antenna fabric from a symmetrical pair of “voles” P-274M.
Attached to the central part with bolts protruding from the inside. The inside of the pipe is filled with foam. Spacer tubes are 15 mm white, used for cold water (NO METAL INSIDE!!!).
Installation of the antenna took about 4 hours if all materials were available. Moreover, I spent most of my time untangling the wire. We “assemble” binoculars from these ferrite glasses: Now about where to get them. Such glasses are used on USB and VGA monitor cords. Personally, I got them when dismantling decommissioned monicas. Which I would use in cases (opening into two halves) as a last resort... Better solid ones... Now about winding. I wound it with a wire similar to PELSHO - multi-core, the lower insulation is made of polymaterial, and the upper insulation is made of fabric. The total diameter of the wire is about 1.2 mm.
So, the binoculars are wound: PRIMARY - 3 turns ends on one side; SECONDARY - 3 turns ends to the other side. After winding, we track where the middle of the secondary is - it will be on the other side of its ends. We carefully clean the middle of the secondary and connect it to one wire of the primary - this will be our COLD LEAD. Well, then everything goes according to the scheme... In the evening I threw the antenna to the Degen 1103 receiver. Everything rattles! On the 160, however, I didn’t hear anyone (7 pm is still early), the 80 is boiling, on the “troika” from Ukraine the guys are doing well on AM. In general, it works great!!!
From publication: EW6MI
Delta Loop by RZ9CJ
Over many years of operation on the air, most of the existing antennas have been tested. When I made all of them and tried to work on the vertical Delta, I realized that how much time and effort I spent on all those antennas was in vain. The only omnidirectional antenna that has brought a lot of pleasant hours behind the transceiver is the vertically polarized Delta. I liked it so much that I made 4 pieces for 10, 15, 20 and 40 meters. The plans are to also do it on 80 m. By the way, almost all of these antennas immediately after construction *hit* more or less SWR.
All masts are 8 meters high. Pipes 4 meters long - from the nearest housing office. Above the pipes - bamboo sticks, two bundles up. Oh, and they break, they are infectious. I've already changed it 5 times. It’s better to tie them in 3 pieces - it will be thicker but will also last longer. The sticks are inexpensive - in general, a budget option for the best omnidirectional antenna. Compared to a dipole - earth and sky. Actually *pierced* pile-ups, which was not possible on the dipole. The 50 Ohm cable is connected at the feed point to the antenna fabric. The horizontal wire must be at a height of at least 0.05 waves (thanks VE3KF), that is, for the 40 meter range it is 2 meters.
P.S. Horizontal wire, you need to place the connection between the cable and the fabric. Changed the pictures a bit, perfect for the site!
Portable HF antenna for 80-40-20-15-10-6 meters
On the website of the Czech radio amateur OK2FJ František Javurek found an antenna design that is interesting in my opinion, which operates on the bands 80-40-20-15-10-6 meters. This antenna is an analogue of the MFJ-1899T antenna, although the original costs 80 euros, and a homemade one costs a hundred rubles. I decided to repeat it. This required a piece of fiberglass tube (from a Chinese fishing rod) measuring 450 mm, with diameters from 16 mm to 18 mm at the ends, 0.8 mm varnished copper wire (disassembled an old transformer) and a telescopic antenna about 1300 mm long (I found only a meter Chinese one from TV, but extended it with a suitable tube). The wire is wound onto a fiberglass tube according to the drawing and bends are made to switch the coils to the desired range. I used a wire with crocodiles at the ends as a switch. This is what happened. Switching ranges and the length of the telescope are shown in the table. You shouldn’t expect any miraculous characteristics from such an antenna; it’s just a camping option that has a place in your bag.
Today I tried it for reception, just sticking it into the grass on the street (at home it didn’t work at all), it received very loudly at 40 meters 3.4 areas, 6 was barely audible. I didn’t have time today to test it longer, but when I try it, I’ll report back to the show. P.S. You can see more detailed pictures of the antenna device here: link. Unfortunately, there has not yet been any notification about the transmission work with this antenna. I’m extremely interested in this antenna, I’ll probably have to make it and try it out. In conclusion, I am posting a photo of the antenna made by the author.
From the website of Volgograd radio amateurs
80 meter antenna
For more than a year, when working on the amateur radio 80-meter band, I have been using the antenna, the structure of which is shown in the figure. The antenna has proven itself to be excellent for long-distance communications (for example, with New Zealand, Japan, the Far East, etc.). The 17 meter high wooden mast rests on an insulating plate, which is mounted on top of a 3 meter high metal pipe. The antenna mount is formed by braces of the working frame, a special tier of braces (their top point can be at a height of 12-15 meters from the roof) and, finally, a system of counterweights that are attached to the insulating plate. The working frame (it is made from an antenna cord) is connected at one end to the counterweight system, and at the other to the central core of the coaxial cable feeding the antenna. It has a characteristic impedance of 75 ohms. The braid of the coaxial cable is also attached to the counterweight system. There are 16 of them in total, each 22 meters long. The antenna is adjusted to a minimum standing wave ratio by changing the configuration of the lower part of the frame (“loop”): bringing its conductors closer or further away and selecting its length A A’. The initial value of the distance between the upper ends of the “loop” is 1.2 meters.
It is advisable to apply a moisture-proof coating to a wooden mast; the dielectric for the support insulator should be non-hygroscopic. The upper part of the frame is attached to the mast through: a support insulator. Insulators must also be inserted into the fabric of the stretch marks (5-6 pieces for each).
From the UX2LL website
80 meter dipole from UR5ERI
Victor has been using this antenna for three months now and is very pleased with it. It is stretched like a regular dipole and this antenna responds well to it from all sides, this antenna only works at 80 m. The whole adjustment consists of adjusting the capacitance and adjusting the antenna in SWR to 1 and after that you need to insulate the capacitance so that moisture does not get in or remove it variable capacity and measure it and install a constant capacity to avoid headaches with sealing the variable capacity.
From the UX2LL website
40 meter antenna with low suspension height
Igor UR5EFX, Dnepropetrovsk.
The “DELTA LOOP” loop antenna, located in such a way that its upper corner is at the height of a quarter wave above the ground, and power is supplied to the loop gap in one of the lower corners, has a high level of radiation of a vertically polarized wave under a small one, about 25-35 ° angle relative to the horizon, which allows it to be used for long-distance radio communications.
A similar emitter was built by the author, and its optimal dimensions for the 7 MHz range are shown in Fig. The input impedance of the antenna, measured at 7.02 MHz, is 160 Ohms, therefore, for optimal matching with the transmitter (TX), which has an output impedance of 75 Ohms, a matching device was used from two quarter-wave transformers connected in series from coaxial cables 75 and 50 Ohms (Fig. 2). The antenna resistance is transformed first to 35 Ohms, then to 70 Ohms. The SWR does not exceed 1.2. If the antenna is more than 10...14 meters away from the TX, to points 1 and 2 in Fig. you can connect a coaxial cable with a characteristic impedance of 75 Ohms of the required length. Shown in Fig. The dimensions of quarter-wave transformers are correct for cables with polyethylene insulation (shortening factor 0.66). The antenna was tested with an ORP transmitter with a power of 8 W. Telegraph QSOs with radio amateurs from Australia, New Zealand and the USA confirmed the effectiveness of the antenna when operating on long-distance routes. 
The counterweights (two quarter-wave ones in a line for each range) lay directly on the roofing felt. In both versions in the ranges of 18 MHz, 21 MHz and 24 MHz SWR (SWR)< 1,2, в диапазонах 14 MHz и 28 MHz КСВ (SWR) < 1,5. Настройка антенны при смене диапазона крайне проста: вращать КПЕ до минимума КСВ. Я это делал руками, но ничто не мешает использовать КПЕ без ограничителя угла поворота и небольшой моторчик с редуктором (например от старого дисковода) для его вращения.
P.S. I made this antenna, and it’s really acceptable, you can work, and work well. I used a device with an RD-09 motor and made a friction clutch, i.e. so that when the plates are fully withdrawn and inserted, slippage occurs. The friction discs were taken from an old reel-to-reel tape recorder. The capacitor is three sections; if the capacity of one section is not enough, you can always connect another one. Naturally, the entire structure is placed in a moisture-proof box. I’m posting a photo, take a look and you’ll figure it out!
Antenna "Lazy Delta" (lazy delta)
The 1985 Radio Yearbook published an antenna with a slightly strange name. It is depicted as an ordinary isosceles triangle with a perimeter of 41.4 m and, obviously, therefore did not attract attention. As it turned out later, it was in vain. I just needed a simple multi-band antenna, and I hung it at a low height - about 7 meters. The length of the RK-75 power cable is about 56 m (half-wave repeater). The measured SWR values practically coincided with those given in the Yearbook.
Coil L1 is wound on an insulating frame with a diameter of 45 mm and contains 6 turns of PEV-2 wire with a thickness of 2...3 mm. HF transformer T1 is wound with MGShV wire on a ferrite ring 400NN 60x30x15 mm, contains two windings of 12 turns each. The size of the ferrite ring is not critical and is selected based on the power input. The power cable is connected only as shown in the figure; if it is turned on the other way around, the antenna will not work.
The antenna does not require adjustment, the main thing is to accurately maintain its geometric dimensions. When operating on the 80 m range, compared to other simple antennas, it loses in transmission - the length is too short.
At the reception, the difference is practically not felt. Measurements carried out by G. Bragin’s HF bridge (“R-D” No. 11) showed that we are dealing with a non-resonant antenna. The frequency response meter shows only the resonance of the power cable. It can be assumed that the result is a fairly universal antenna (from simple ones), has small geometric dimensions and its SWR is practically independent of the height of the suspension. Then it became possible to increase the height of the suspension to 13 meters above the ground. And in this case, the SWR value for all major amateur bands, except for 80 meters, did not exceed 1.4. On the eighty, its value ranged from 3 to 3.5 at the upper frequency of the range, so to match it, a simple antenna tuner is additionally used. Later it was possible to measure SWR on the WARC bands. There the SWR value did not exceed 1.3. A drawing of the antenna is shown in the figure.
V. Gladkov, RW4HDK Chapaevsk
Http://ra9we.narod.ru/
Inverted V Antenna - Windom
Radio amateurs have been using the Windom antenna for almost 90 years, which got its name from the name of the American shortwave operator who proposed it. Coaxial cables were very rare in those years, and he figured out how to power an emitter half the operating wavelength with a single-wire feeder.
It turned out that this can be done if the antenna feed point (connection of a single-wire feeder) is taken approximately at a distance of one third from the end of the emitter. The input impedance at this point will be close to the characteristic impedance of such a feeder, which in this case will operate in a mode close to the traveling wave mode.
The idea turned out to be fruitful. At that time, the six amateur bands in use had multiple frequencies (non-multiples of WARC bands did not appear until the 70s), and this point turned out to be suitable for them as well. Not an ideal point, but quite acceptable for amateur practice. Over time, many variants of this antenna appeared, designed for different bands, with the general name OCF (off-center fed - with power not in the center).
In our country, it was first described in detail in the article by I. Zherebtsov “Transmitting antennas powered by a traveling wave,” published in the journal “Radiofront” (1934, No. 9-10). After the war, when coaxial cables came into amateur radio practice, a convenient power supply option for such a multi-band emitter appeared. The fact is that the input impedance of such an antenna in the operating ranges does not differ very much from 300 Ohms. This allows you to use common coaxial feeders with a characteristic impedance of 50 and 75 Ohms through HF transformers with a transformation ratio of 4:1 and 6:1 to power it. In other words, this antenna easily became part of everyday amateur radio practice in the post-war years. Moreover, it is still mass-produced for shortwave frequencies (in various versions) in many countries around the world.
It is convenient to hang the antenna between houses or two masts, which is not always acceptable due to the real circumstances of housing, both in the city and outside the city. And, naturally, over time, an option arose to install such an antenna using just one mast, which is more feasible to use on a residential building. This option is called Inverted V - Windom.
The Japanese shortwave operator JA7KPT, apparently, was one of the first to use this option for installing an antenna with a radiator length of 41 m. This length of the radiator was supposed to provide it with operation in the 3.5 MHz range and higher frequency HF bands. He used a mast 11 meters high, which for most radio amateurs is the maximum size for installing a homemade mast on a residential building.
Radio amateur LZ2NW (http://lz2zk. bfra.bg/antennas/page1 20/index. html) repeated his version Inverted V - Windom. Its antenna is shown schematically in Fig. 1. The height of his mast was approximately the same (10.4 m), and the ends of the emitter were spaced from the ground at a distance of about 1.5 m. To power the antenna, a coaxial feeder with a characteristic impedance of 50 Ohms and a transformer (BALUN) with a coefficient of transformation 4:1.
Rice. 1. Antenna diagram
The authors of some variants of the Windom antenna note that it is more expedient to use a transformer with a transformation ratio of 6:1 when the wave impedance of the feeder is 50 Ohms. But their authors still make most antennas with 4:1 transformers for two reasons. Firstly, in a multi-band antenna, the input impedance “walks” within certain limits around the value of 300 Ohms, therefore, at different ranges, the optimal values of the transformation ratios will always be slightly different. Secondly, a 6:1 transformer is more difficult to manufacture, and the benefits from its use are not obvious.
The LZ2NW, using a 38m feeder, achieved SWR values less than 2 (typical value 1.5) on almost all amateur bands. The JA7KPT has similar results, but for some reason it dropped out in the SWR range of 21 MHz, where it was greater than 3. Since the antennas were not installed in an “open field,” such a dropout on a specific band may be due, for example, to the influence of the surrounding “ gland".
LZ2NW used an easy-to-manufacture BALUN, made on two ferrite rods with a diameter of 10 and a length of 90 mm from the antennas of a household radio. Each rod is wound into two wires, ten turns of wire with a diameter of 0.8 mm in PVC insulation (Fig. 2). And the resulting four windings are connected in accordance with Fig. 3. Of course, such a transformer is not intended for powerful radio stations - up to an output power of 100 W, no more.
Rice. 2. PVC insulation
Rice. 3. Winding connection diagram
Sometimes, if the specific situation on the roof allows, the Inverted V - Windom antenna is made asymmetrical by attaching the BALUN to the top of the mast. The advantages of this option are clear - in bad weather, snow and ice, settling on the BALUN antenna hanging on the wire, can break it.
Material by B. Stepanov
Compactantenna for main KB bands (20 and 40 m) - for summer cottages, trips and hikes
In practice, many radio amateurs, especially in the summer, often need a simple temporary antenna for the most basic HF bands - 20 and 40 meters. In addition, the place for its installation may be limited, for example, by the size of a summer cottage or in a field (fishing, on a hike - near a river) by the distance between the trees that are supposed to be used for this.
To reduce its size, a well-known technique was used - the ends of the 40-meter range dipole are turned to the center of the antenna and located along its canvas. As calculations show, the characteristics of the dipole change insignificantly if the segments subjected to such modification are not very long compared to the operating wavelength. As a result, the total length of the antenna is reduced by almost 5 meters, which in certain conditions can be a decisive factor.
To introduce the second band into the antenna, the author used a method that in English amateur radio literature is called “Skeleton Sleeve” or “Open Sleeve.” Its essence is that the emitter for the second band is placed next to the emitter of the first band, to which the feeder is connected.
But the additional emitter does not have a galvanic connection with the main one. This design can significantly simplify the design of the antenna. The length of the second element determines the second operating range, and its distance to the main element determines the radiation resistance.
In the described antenna for a 40-meter range emitter, mainly the lower (according to Fig. 1) conductor of a two-wire line and two sections of the upper conductor are used. At the ends of the line they are connected to the lower conductor by soldering. The 20 meter range emitter is formed simply by a section of the upper conductor
The feeder is made of RG-58C/U coaxial cable. Near the point of its connection to the antenna there is a choke - current BALUN, the design of which can be taken from. Its parameters are more than sufficient to suppress common-mode current along the outer braid of the cable on the ranges of 20 and 40 meters.
Results of calculation of antenna radiation patterns. performed in the EZNEC program are shown in Fig. 2.
They are calculated for an antenna installation height of 9 m. The radiation pattern for the range of 40 meters (frequency 7150 kHz) is shown in red. The gain at the maximum of the diagram in this range is 6.6 dBi.
The radiation pattern for the 20 meter band (frequency 14150 kHz) is shown in blue. In this range, the gain at the maximum of the diagram was 8.3 dBi. This is even 1.5 dB more than that of a half-wave dipole and is due to a narrowing of the radiation pattern (by about 4...5 degrees) compared to a dipole. The antenna SWR does not exceed 2 in the frequency bands 7000...7300 kHz and 14000...14350 kHz.
To make the antenna, the author used a two-wire line from the American company JSC WIRE & CABLE, the conductors of which are made of copper-plated steel. This ensures sufficient mechanical strength of the antenna.
Here you can use, for example, the more common similar line MFJ-18H250 from the well-known American company MFJ Enterprises.
The appearance of this dual-band antenna, stretched among the trees on the river bank, is shown in Fig. 3.
The only drawback can be considered that it can really be used as a temporary one (at the dacha or in the field) in spring-summer-autumn. It has a relatively large surface area (due to the use of a ribbon cable), so it is unlikely to withstand the load of snow or ice in winter.
Literature:
1. Joel R. Hallas A Folded Skeleton Sleeve Dipole for 40 and 20 Meters. - QST, 2011, May, p. 58-60.
2. Martin Steyer The Construction Principles for “open-sleeve”-Elements. - http://www.mydarc.de/dk7zb/Duoband/open-sleeve.htm.
3. Stepanov B. BALUN for KB antenna. - Radio, 2012, No. 2, p. 58
A selection of broadband antenna designs
Enjoy watching!
Multi-band vertical antenna
Vertical Ground Plane antennas do not have broadband and, without adjustment, can only operate in a narrow frequency band.
The so-called “thick” vertical antennas, the radiating surface of which has various shapes, are free from this drawback and operate satisfactorily in the frequency range with an overlap coefficient of up to 3. The most widespread are conical ( Fig.1a ) and exponential ( Fig.1b ) antennas.
Fig.1
The characteristic impedance of a conical antenna is constant along its length and depends on the alpha angle at the apex of the cone. The broadband properties of the antenna increase with increasing alpha angle and reach optimum at 60...70 degrees; in this case, the wave impedance of the antenna is approximately 70...80 Ohms.
An exponential antenna, the wave impedance of which increases along its length approximately according to an exponential law, has the same broadband properties as a conical one. At the same time, an exponential antenna has a great advantage - its maximum diameter is 3 times smaller than a conical one.
For the short-wave range, it is practically not possible to construct an antenna with a continuous radiating surface in the form of the figures shown in Fig.1. Such antennas are made of tubes or wires. For exponential antennas, in addition, the smooth envelope is replaced by a broken one.
At the radio station UW4HW an exponential antenna is used for the range of 14, 21 and 28 MHz, the design of which is shown in Fig.2 . The radiating antenna system is formed by six wires located in vertical planes at an angle of 60 degrees to one another.
Fig.2
At the base and top of the antenna, the wires are electrically connected together and secured to the supporting mast using insulators. The latter is made of three pipe sections of equal length, connected by insulating inserts. A wooden pole can also be used as a supporting mast. The shape of the antenna is ensured by spacers fixed at the level of one third of the total height of the antenna. Each spacer ends in an insulator through which the antenna wire passes.
If necessary, you can avoid installing spacers and ensure the shape of the antenna using guy wires attached to the wires at the bend point using insulators. In this case, if the mast has sufficient rigidity, you can do without additional guy wires.
The antenna is powered using a coaxial cable with a characteristic impedance of 75 Ohms. The central core is connected to the lowest point of the antenna, and the shielding braid is connected to a good ground when installing the antenna directly on the ground or to artificial ground if the antenna is installed on the roof of a house.
The artificial ground can be a metal roof or six horizontal wires radiating out from the base of the antenna. The wires of the artificial ground are located in the same vertical planes with the corresponding radiating wires of the antenna and have a length equal to the length of the radiating wires.
The antenna and artificial ground are made of copper wire with a diameter of 1.5 mm. Practically measured SWR values in the frequency range are 14.0; 21; 29.7 MHz are in the range of 1.2...1.9. It is easy to calculate antenna sizes for other frequency ranges by specifying the length of the antenna wires within the limits:
and the alpha angle at the base of the antenna is within 60...70 degrees. Experience with this antenna shows that it is superior in performance to the "Ground Plane" and due to its simplicity of execution, it can be successfully used in amateur radio practice.
Engineer Yu. Matijchenko (UW4HW), master of sports. "Radio" No. 12/1968
Comments on the article:
Vertical multi-band antennas
(Description and practical designs for application)
It is proposed to consider methods for constructing and actual designs of multi-band vertical whip antennas in the short wave range. All antennas are easy to set up and provide high parameters when operating on the air.
Practice shows that the lack of free space in the city (mainly the roofs of houses) for placing amateur radio HF antennas and the increase in the number of open amateur bands has led to an increase in the popularity of multi-band vertical antennas. After all, multi-band vertical antennas do not take up much space for their installation. Using vertical antennas, it is possible to organize amateur radio communications in urban environments.
Tri-band vertical antenna
If there is not enough space on the roof of an apartment building to install a separate vertical antenna for each upper amateur HF band, you can use a combined three-band antenna. The diagram of such an antenna is shown in Fig. 1.
Rice. 1. Combined tri-band antenna
Three (3) quarter wave vibrators are connected in parallel to the center core of the coaxial cable. At least two quarter-wave counterweights for each antenna operating range are connected to the braid of the coaxial cable.
In table 1 shows a combination of ranges in which parallel-connected antenna vibrators have minimal influence on each other. Using more than three vibrators to create a multi-band vertical antenna is not advisable. The capacitive component of the impedance of a multi-band vertical antenna will be comparable to the active part of its input impedance at the upper ranges of the antenna, as a result of which the efficiency of the antenna at them drops significantly.
Table 1. Combination of operating ranges of a combined tri-band antenna
The design of this multi-band antenna depends only on the real capabilities of the radio amateur himself. The antenna vibrators can be rigidly screwed to a metal corner, as shown in Fig. 2.
If the elasticity of the vibrators does not allow achieving rigidity of the antenna structure, then the distance between them relative to each other can be fixed using plastic insulators, as shown in Fig. 3.
On the contrary, sufficiently rigid antenna vibrators can be arranged in a fan, as shown in Fig. 4.
Pins for working in high-frequency ranges can be made of copper or duralumin tubes, or can be stretched from thick copper wire. It is advisable to install a high-frequency choke at the end of the coaxial power cable.
Rice. 2. Location of antenna vibrators on a metal corner
Rice. 3. Fixing the antenna vibrators
Rice. 4. Fan arrangement of antenna vibrators
The number of resonant counterweights used with a multi-band vertical antenna must be at least two for each antenna operating range. If the antenna is placed at a low height above a metal roof and the coaxial cable braid is in good contact with this roof, a multi-band vertical antenna can be used without counterweights.
Tri-band antenna for low frequency bands
For low-frequency HF bands, it is advisable to make antenna vibrators from copper wire with a diameter of 1-2 mm. At low frequency ranges, the influence of objects surrounding the antenna on it will be high. Consequently, it will most likely be necessary to adjust the length of each vibrator at each antenna operating range.
When constructing the antenna, it is necessary to provide a constructive possibility for such adjustment. For this purpose, it is advisable to make the antenna vibrators a little more than a quarter of the wavelength. In this case, it is advisable to tune the vibrators of a multi-band vertical antenna to resonance for each range of operation using shortening capacitors, as shown in Fig. 5.
Rice. 5. Tuning the antenna vibrators to resonance using shortening capacitors
Of course, you can tune the antenna to resonance using shortening capacitors not only in the lower short-wave ranges but also in the upper ones. The capacitance of the shortening capacitor can be up to 100 pF when operating antenna vibrators in the ranges of 6-17 m, up to 150 pF when operating antenna vibrators in the ranges of 20-30 m, 200 pF when operating antenna vibrators in the ranges of 40-80 m, and up to 250 pF when the antenna operates at 160 m.
Serious attention should be paid to the fact that a high-frequency choke must be installed at the end of the coaxial power cable of the above-described antennas. This choke prevents high-frequency currents from flowing into the outer shell of the coaxial cable, which in this case will serve as the radiating part of the antenna. This will lead to an increase in the level of interference when the antenna is transmitting. The simplest design of such a high-frequency choke is 10 - 30 ferrite rings tightly wrapped at the end of a coaxial cable.
You can use ferrite tubes that fit onto the cords of computer monitors. Such ferrite tubes can also be quite successfully used to create high-frequency chokes at the end of a coaxial antenna cable.
Vertical pin in multi-band antenna operation
It is common among radio amateurs to use one vertical vibrator to operate on several amateur bands. However, by simply selecting the physical length of the antenna vibrator, it is impossible to adjust its input impedance to the characteristic impedance of the coaxial cable on several amateur bands. Therefore, it is not possible to use coaxial cable to feed such an antenna directly. In this case, it is quite possible to use a two-wire open line to power the vertical antenna. A two-wire line allows operation with a high SWR value.
In this antenna system design, a two-wire line at one end is connected directly to the antenna pin, and the other end of the two-wire line is connected through a matching device to the transceiver. The diagram of a multi-band vertical antenna powered via a two-wire line is shown in Fig. 6.
Rice. 6. Diagram of a multi-band vertical antenna with power supply over a two-wire line
The antenna consists of a rod, length LA, and at least four counterweights, length LC. For the effective operation of a vertical antenna, the pin of which is not tuned into resonance with the signal emitted by it, it is necessary that the electrical length of the pin be at least 1/8 of the wavelength. With this length, the active input impedance of the pin is about five ohms. This is the extreme value of the antenna input impedance that can still be satisfactorily matched when feeding a whip antenna using a two-wire line. Therefore, in order for the antenna to operate in the amateur bands of 6 - 80 meters, it is enough that the length of its vertical part is at least 5 meters.
As indicated in many amateur radio sources, for the operation of such a surrogate vertical multi-band antenna, it is not necessary to use resonant counterweights, which, of course, improve the performance of the antenna, but at the same time significantly complicate its design. Four counterweights with a length equal to the height of the pin are sufficient.
There is still no consensus among radio amateurs about how long a pin should be used to create a multi-band vertical antenna powered by a two-wire open line. There are two opposing opinions about the length of the pin. The first is that the pin must have resonances on the upper amateur bands on which the antenna is used, and the second is that it is not necessary for the pin to have resonances on the operating ranges of the antenna.
Theoretically, for the operation of this antenna, it makes no difference whether a pin of resonant length is used, or the resonance of the pin lies outside the amateur band and, therefore, compensation for the reactive part of the antenna impedance will be required through a matching device. In practice, however, it may even turn out that a multi-band non-resonant whip antenna fed via a two-wire line will work more efficiently. Often, using a two-wire line, it is easier to match a non-resonant whip than when using a whip antenna that has resonances on several amateur bands.
An antenna of resonant length will necessarily have an input impedance of several thousand ohms on any amateur band, i.e. there will be a voltage node at its input. This can make it difficult to match the pin with the transmission line and then with the matching device on the resonant range. Since the number of supporters of resonant and non-resonant multi-band whip antennas is almost the same, we will analyze both of these antenna options.
The classic non-resonant design of a multi-band vertical rod used by radio amateurs around the world must be recognized as the WB6AAM antenna, discussed in the literature. The antenna rod and its counterweights have a length of 6.1 meters. In table Figure 2 shows the gain values of the WB6AAM antenna relative to a quarter-wave monopole vibrator operating on the compared range. As can be seen from this table, the parameters of this antenna are very good in the ranges of 6 - 20 meters, satisfactory when operating in the ranges of 30-40 meters, and the antenna can be used for auxiliary work on the range of 80 meters.
In the literature, the radio amateur DL2JWN describes a non-resonant antenna with a length of the vertical part and counterweights equal to 6.7 meters. It is obvious that the parameters of the DL2JWN antenna differ slightly from the parameters of the WB6AAM antenna. In practice, for the operation of the antenna, it makes no difference what length of the rod is used to build a multi-band vertical antenna, either 6.1 or 6.7 meters. The length of the pin depends only on the convenience of using certain materials to make a multi-band antenna.
Table 2. WB6AAM antenna gain values
Let's look at multi-band vertical antennas powered by a two-wire line and having a pin of resonant length for some of its operating ranges. The antenna, with a height of the vertical part and a length of counterweights of 508 cm, was described by a radio amateur with the call sign W4VON in the literature. This antenna operates in resonant mode on the 10 and 20 meter bands. The height of the W4VON antenna is less than the height of the WB6AAM antenna. Consequently, the W4VON antenna performs slightly less efficiently than the WB6AAM antenna. The W4VON antenna is powered using a two-wire line, indicating the possibility of its operation in the amateur bands of 10 - 80 meters.
A vertical multi-band antenna with a vertical part length of 10 meters and three counterweights of the same length is described by a radio amateur with the call sign W1AB in the literature. The antenna has resonances on the amateur bands of 10, 20 and 40 meters. This antenna, due to the relatively large length of the vertical part, can provide operation not only on the ranges of 10 - 80 m, as indicated in its description, but also on the range of 160 meters. Its gain will be approximately one and a half times higher compared to the WB6AAM vertical antenna (see Table 2). Of course, if there is sufficient space to place the antenna, materials, and experience in installing high vertical antennas, it is better to use a multi-band antenna with a vertical part length of 10 meters or more.
A two-wire transmission line for powering multi-band vertical antennas can be used with any characteristic impedance. This can be a homemade two-wire line with a random characteristic impedance; you can use a standard ribbon cable, for example the CATV type.
With a power supplied to the antenna of no more than 100 watts, a telephone two-wire cable of the type TRP, TRV, PRPP, which is better known among radio amateurs as “noodles,” can be used as a two-wire transmission line. Unfortunately, this cable, when exposed to atmospheric conditions, usually fails after a few years. This occurs due to the destruction of the plastic outer insulation, and as a result, oxidation of the transmission line cores. A transmission line with oxidized cores is completely unsuitable for use as a high frequency power transmission line.
Antennas powered by an open transmission line are still rarely used by radio amateurs. This, in my opinion, can only be explained by the lack of inexpensive open transmission lines on sale that can operate for quite a long time under the influence of atmospheric conditions. Using homemade open transmission lines is not always convenient. The telephone cable TRP, TRV, PRPP, available to radio amateurs, “lives” in the open air for only 2 - 3 years. This limits its use for building antennas.
However, recently, two-wire imported transmission lines (such as our CATV) of various wave impedances are beginning to appear on wide sale and at reasonable prices. It is hoped that interest in multi-band vertical antennas powered by a two-wire line will increase again among radio amateurs.
Antenna UA1DZ
It is precisely because of the shortage of open transmission lines that radio amateurs are attempting to power a multi-band antenna via a coaxial cable using various matching devices located directly on the antenna pin. One of the most successful designs of a multi-band vertical antenna was carried out by the radio amateur UA1DZ. The earliest description of this antenna, given by the radio amateur UA1DZ himself, was given in the literature. The design of the UA1DZ multi-band vertical antenna and its matching devices is shown in Fig. 7.
Rice. 7. Design of multi-band vertical antenna UA1DZ
The height of the UA1DZ antenna rod is 9.3 m. This length was not chosen by chance. To construct the antenna whip, radio amateur UA1DZ used an old military whip antenna, the length of which was 9.3 meters. The antenna counterweights are 9.4 m long. They are made of wire with a diameter of 1.5 mm and are located opposite each other.
The initial matching of the input impedance of the antenna pin and the counterweight system with the characteristic impedance of the coaxial power cable is carried out using an open line “A”, approximately one meter long and a characteristic impedance of 450 Ohms. It serves to preliminary transform the input impedance of the antenna system into the characteristic impedance of the supply coaxial cable. Next, using a matching section of coaxial cable “B” with a characteristic impedance of 75 Ohms, further transformation of the input impedance of the antenna system is carried out into a characteristic impedance of the coaxial power cable of 75 Ohms. The section of coaxial cable “B” compensates for the reactive component in the antenna power line. The antenna can operate on the bands 7, 14, 21, MHz with SWR less than 2.
It should be noted that in different descriptions of the UA1DZ antenna, the lengths of the matching lines A, B, and C were given slightly different from each other. Modern antenna modeling programs have made it possible to find the optimal lengths for these matching lines. They were calculated by radio amateur VA3TTT (ex UA9XCD, UZ3XWB). The literature provides optimized lengths for these matching lines. The optimized line lengths are shown in Fig. 7 in brackets. As you can see, only for line B the optimized length and the length of the matching section indicated by the radio amateur UA1DZ in the first description of this antenna given in the literature do not coincide slightly.
Fine tuning of the UA1DZ antenna can be done using a bridge resistance meter. It should be located at the input of the antenna matching devices. By reducing the length of segment “A”, a minimum SWR is achieved on the 7 and 21 MHz bands. Shortening the length of line A by 5 centimeters causes the resonance to shift upward by 200 kHz at 21 MHz, and by 60 kHz at 7 MHz. It is quite possible to configure the antenna so that the minimum SWR is within the 21 and 7 MHz bands. When tuning the antenna to operate on these bands, the SWR of the 14 MHz antenna should fall into place. As an open line, you can use either a homemade open line with a characteristic impedance of 450 Ohms, or a two-wire industrial line.
According to radio amateur VA3TTT, on the 7 MHz band this antenna has a gain of 3.67 dB, on the 14 MHz band the gain is 4 dBi, and on the 21 MHz band the gain is 7.6 dB. The literature indicates the possibility of operating the UA1DZ antenna on the 28 MHz band, however, studies conducted by VA3TTT did not allow achieving low SWR values on this range when using the matching devices specified here at the antenna input.
At the end of the coaxial cable feeding the UA1DZ antenna, a high-frequency choke should be installed, similar to the one described in this chapter in the paragraph on tri-band antennas.
Multi-band vertical antennas with barrier circuits
Antennas with barrier circuits installed in its surface are widely used among radio amateurs. This antenna was first patented in the USA by H. K. Morgan, patent No. 2229856 from 1938 (according to the source). A description of multi-band antennas with barrier circuits first appeared in the amateur radio literature. Let's look at the principle of operation of an antenna with barrier circuits. The diagram of such an antenna is shown in Fig. 8.
Rice. 8. Vertical antenna with barrier contours
In this antenna, section “A” is configured to operate in the 10 meter range. The L1C1 barrier circuit, configured for the 10-meter range, “turns off” the upper part of the antenna when it operates in this range. When the antenna operates in the range of 15 meters, section “B” extends section “A” to a length that is resonant in this range. The L2C2 circuit, configured for the 15-meter range, turns off the upper part of the antenna when it operates in the 15-meter range. To operate on a range of 20 meters, the antenna is tuned to resonance by changing the length of section “B”. Similarly, the antenna can be configured for other amateur radio HF bands. In practice, radio amateurs usually do not use vertical antennas with more than one barrier circuit in the antenna web. This is due to the fact that the antenna sections must be electrically isolated from each other, and in practice it is difficult to make an insulating connection strong enough for the antenna to exist.
In 1955, an article by radio amateur W3DZZ appeared in the literature about a multi-band antenna in which only one barrier circuit was used. Thanks to the appropriate distribution of high-frequency current that this circuit provided, this antenna could operate on several bands. Below we will look at the operation of several popular multi-band antennas that use only one circuit.
One of the most popular vertical barrage antennas used on 10 and 15 meters is the antenna described by amateur radio operator WA1LNQ in the literature. The diagram of this antenna is shown in Fig. 9. It is made of two tubes, 240.7 and 62.9 cm long, insulated from each other. The length of the insulating insert is 5.8 cm. A barrier circuit coil is wound around this insert. The coil is made of a copper tube with a diameter of 3–5 mm and contains 2 turns of wire with a pitch of 1 turn per 25 mm of winding. The average coil diameter is 55 mm. A piece of coaxial cable with a characteristic impedance of 50 Ohms with an initial length of 80 cm is used as a capacitor, which is gradually shortened during the tuning process once the minimum SWR is reached in the range of 10 meters. After this adjustment, it is possible to slightly adjust the length of the upper section of the antenna according to the minimum SWR value on the 15-meter range. To make the antenna, copper or aluminum tubes with a diameter of 18-25 mm can be used.
Rice. 9. Antenna WA1LNQ
Another popular multi-band vertical antenna with barrier circuits is the K2GU four-band vertical antenna, described in the literature.
The antenna is operational in the amateur bands of 10, 15, 20, 40 meters. The antenna diagram is shown in Fig. 10. A 50 ohm coaxial cable is used to power the antenna. The SWR actually achievable with it is 1.3:1 at 7.05 MHz; 1.1:1 at 14.1 MHz; 2.5:1 at 21.2 MHz; 1.1:1 at 28.5 MHz.
Rice. 10. Quad-band vertical antenna with one barrier circuit
Let's consider the operation of the antenna. On the 20-meter range, the LC barrier circuit turns off the upper section of antenna “A”. The remaining section “B” effectively works as a quarter-wave vibrator. On the 40m range, the geometric length of the antenna is less than a quarter wavelength, but the LC circuit on this range has an inductive reactance that compensates for the capacitive component of the short pin. The circuit here works as an extension inductance that increases the electrical length of the antenna to a resonant quarter-wave in the range of 40 meters.
On the 10 meter range, the LC circuit has a capacitive nature of resistance, which brings the total electrical length of the antenna to 3/4 wavelength. On the 15-meter range, the antenna has an SWR greater than 2.5:1, but at the same time, when used in conjunction with a transceiver, an external matching device can operate effectively on it.
Let's consider the design of the barrier circuit. The coil used in it is frameless, contains 10 turns, the diameter of its wire is 2 mm, the coil winding diameter is 6 cm, and the winding pitch is 4 mm. The LC barrier circuit must be tuned to resonance at a frequency of 14.1 MHz. It is pre-configured using GIR. During setup, an additional capacitor with a capacity of 2–3 pF is connected in parallel with the loop capacitor. This capacitor simulates the capacitance between the insulating insert of the upper and lower ends of the antenna. The loop capacitor must be protected from exposure to atmospheric influences. This antenna is tuned by changing the length of sections “A” and “B” according to the lowest SWR of the antenna on its operating ranges.
Using a similar principle of shortening and lengthening the antenna web to a resonant one with the help of a barrier circuit, it is possible to build antennas that operate on other amateur bands. In the domestic literature, a vertical antenna with one barrier circuit was described, operating in the ranges of 10, 15, 20, 40, 80 meters. The diagram of this antenna is shown in Fig. eleven.
Rice. 11. Five-band vertical antenna with one barrier circuit
The antenna's barrier circuit is made up of an 8.3 μH inductance coil and a 60 pF capacitor. This is a common circuit used in the W3DZZ antenna, and its design data has been repeatedly cited in amateur radio literature, for example in. We present here the data for its implementation. The diameter of the coil is 50 mm, the number of turns is 19, the winding length is 80 mm, a wire with a diameter of 1.5 mm is used.
Let's consider the operation of this antenna. When operating on a range of 40 meters, the barrier circuit turns off the upper part of antenna “A”, and the electrical length of the antenna is ?/4. On the 80 meter range, the barrier circuit coil has inductive reactance and extends the short antenna to an electrical length of 1/4 wavelength in this range. At a range of 20 meters, the barrier circuit has a capacitive nature of resistance, and the electrical length of the antenna is shortened to 3/4 of the wavelength. When operating on the 10 and 15 meter bands, due to the capacitive component of the barrier circuit, the antenna is shortened, respectively, to an electrical length of 7/4 and 5/4 wavelength.
For effective operation of this antenna, a system of resonant counterweights is required with at least 4 counterweights for each antenna operating range. The antenna can be powered via a coaxial cable with a characteristic impedance of 50 or 75 Ohms with an electrical length that is a multiple of half the wavelength in the range of 80 meters. With a cable shortening factor of 0.66, its physical length will be equal to 27.9 meters. In this case, the SWR of the antenna in the operating ranges of the antenna does not exceed 2. For the manufacture of a vertical vibrator, aluminum pipes with a diameter of 40 -50 mm can be used. The large diameter of the pipes is due to the significant height of the antenna, and, therefore, the mechanical strength of its structure is necessary.
A high-frequency choke must be installed at the end of the coaxial cable feeding any of the multi-band vertical barrage antennas described here. The design of this choke can be similar to the choke that was described in this chapter in the paragraph on tri-band antennas.
Open Sleeve
At the end of this chapter, we will focus on a very interesting multi-band antenna known as “Open Sleeve”. This antenna was developed in 1946 at the Stanford Research Institute by the famous researcher Dr. J. T. Bollijahn. At first, this antenna was not widely used. But in the last decade, interest in this antenna has increased, both among radio amateurs and among professionals. This is due to the fact that, currently, using widely used computer programs for calculating antennas, it is possible to simulate a structurally simple multi-band antenna.
Let's look at the operating principle of the Open Sleeve antenna. Suppose we install a quarter-wave vertical antenna on the 20-meter range, as shown in Fig. 12a. Such an antenna, 5.1 meters long, when located above an ideal conducting surface, has an input impedance of 36 Ohms. This antenna can be relatively easily matched with a coaxial cable with a characteristic impedance of 50 or 75 Ohms. Now let's place a 2.5 meter long wire next to this quarter-wave vertical antenna with a range of 20 meters. This wire is connected to ground (or to the braid of the coaxial cable), and is located at a distance of approximately 10 centimeters from the antenna pin (Fig. 12b).
Rice. 12. Transition from a quarter-wave antenna to an Open Sleeve antenna
What has changed in the performance of this vertical antenna on the 20 meter band? An additional conductor connected to ground and located next to the antenna vibrator slightly lowered the resonant frequency of the vertical antenna. In order to “return the tuning frequency of the antenna vibrator to its place” for the 20-meter range, it needs to be shortened slightly.
What has changed in the operation of this antenna on other bands, for example, on 10 meters? The input impedance of a “pure” vertical antenna with a height of 5.1 meters and an electrical length for a range of 10 meters with a length of 0.5 wavelength is extremely high. But with an additional conductor located next to the antenna vibrator, the equivalent circuit of the antenna system will correspond to that shown in Fig. 13.
Rice. 13. Open Sleeve Antenna Equivalent Circuit
On a range of 10 meters, it can be considered that the part of the vibrator of the antenna “L”, 2.5 meters long, which has an input impedance Z1 at point “A”, is connected through a quarter-wave line having a characteristic impedance Z2, connected to the supply coaxial cable, which has a wave impedance resistance Z3. By appropriately selecting Z1, Z2, Z3, you can match the antenna vibrator for operation on the 10-meter range. Input impedance Z1 depends on the length of the antenna part “L”, input impedance Z2 of the line formed by the antenna vibrator and the additional conductor near it depends on the physical dimensions of this line, Z3 is the standard characteristic impedance of a coaxial cable. It can be equal to 50 or 75 Ohms. Therefore, only by adding one additional conductor near the antenna, it is possible to synthesize a dual-band antenna! In this antenna, the main vibrator is usually called the Master vibrator, and the auxiliary vibrators, which make the antenna work in its upper ranges, are usually called Slave vibrators.
Previously, the practical implementation of such antennas was difficult. There were two ways to create such antennas. The first of them is antenna prototyping. In order to construct an antenna with satisfactory parameters, it was necessary to carry out many experiments. The second way is to calculate the antenna parameters on paper. However, mathematical optimization of one dual-band antenna required hundreds of calculations! In the 50-60s, these calculations were made using a slide rule, then using a computer using lamps and transistors. Only the rapid development of computers in the 80s and 90s of the 20th century eliminated the complexity of the numerous calculations required to optimize this antenna. Now a modern, inexpensive computer program for calculating and modeling antennas, and even its free demo version, can calculate an Open Sleeve antenna.
Of course, a radio amateur can immediately ask a question. Can only dual-band Open Sleeve antennas be built using the above method? Of course not! Using this principle, you can build three, four and even five band antennas! Let us consider, as an example, the construction of a tri-band antenna designed to operate in the ranges of 10, 15 and 20 meters. The design of such an antenna is shown in Fig. 14, the equivalent circuit of the antenna is shown in Fig. 15 .
Rice. 15. Antenna equivalent circuit
The antenna works as follows. On a range of 20 meters at the point where the coaxial power cable is connected (point “A”), the input impedance Z1, which the antenna vibrator has, is equal to the characteristic impedance of this coaxial cable. This equality is fulfilled taking into account the influence of closely spaced conductors S1 and S2 on the parameters of the antenna vibrator. On a range of 10 meters, the input impedance Z2, which is part of the antenna vibrator with length L1 at point “B”, is reduced to the characteristic impedance of the coaxial cable using transformer T1. On a range of 15 meters, the input impedance Z3, which has a part of the antenna vibrator of length L2 at the point at point “C”, is reduced to the characteristic impedance of the coaxial cable using transformer T2.
It is very difficult to calculate the dimensions of a tri-band antenna using a slide rule. Such a calculation may probably take more than one month of hard work. That is why the widespread development of Open Sleeve antennas, and especially their three- and four-band variants, began only in our time. A time when antenna calculation programs became widely available and computer speeds increased.
The Open Sleeve antenna requires a good radio ground to operate. The best option is to place the antenna above a metal conductive roof. If this condition cannot be met, then it is necessary to use 3-5 resonant counterweights for the lower range of the antenna. It is not advisable to use resonant counterweights for the upper ranges of antenna operation.
If the antenna is made exactly according to the calculated dimensions, its resonant frequencies should already be in the amateur bands. However, due to the influence of surrounding objects, due to errors in the imprecise execution of the antenna in size, the Open Sleeve antenna usually requires slight adjustment in the actual conditions of its installation. Let's walk through the process of setting up the Open Sleeve antenna. Tuning the antenna consists of obtaining the value of its input impedance at the terminals for connecting the coaxial power cable equal to the characteristic impedance of this coaxial cable. It is convenient to measure the input impedance of this antenna system using a high-frequency bridge.
Rice. 16. Setting up a dual-band Open Sleeve antenna
We determine the resonant frequency and input impedance of the antenna in the upper range. Let's say that the upper resonant frequency of the antenna is lower than required, and the input impedance is higher than the characteristic impedance of the coaxial cable. This is the most favorable option when setting up an antenna. We bring element S closer to vibrator M. As the distance W between vibrator M and element S decreases, the wave impedance of the matching transformer formed by element S and part of vibrator M decreases. As a result, the input impedance of the antenna on the side fed by its coaxial cable decreases. As element S approaches vibrator M, the upper frequency of the antenna increases. If, with the help of only one approach of the element S to the vibrator M, it is not possible to set the upper range of the antenna in the desired area, then the length of the element S will have to be changed.
If the input impedance of the system at resonance is already 50 Ohms, and the resonant frequency is lower than the required one, then you can try to shorten the element S. Obviously, in this case, the antenna matching transformer is tuned below the required frequency. Reducing the length of the transformer (or the length of element S) will increase the frequency of its operation. After reducing the length of the transformer (element S), by moving this element closer or further relative to the vibrator “M”, an input impedance of 50 Ohms is again achieved at the upper operating frequency of the antenna.
If, on the contrary, it turns out that with an input impedance of 50 Ohms, the upper operating frequency of the Open Sleeve antenna is higher than necessary, increase the length of the “S” element, or, which is the same thing, reduce the tuning frequency of the matching transformer. Based on the above, the strategy for tuning the antenna is clear.
- Approaching the element “S” to the vibrator “M” lowers the input impedance of the antenna and increases its resonant frequency.
- Removing element “S” from vibrator “M” increases the input impedance of the antenna and lowers its operating frequency.
- Increasing the length of the “S” element (or, equivalently, increasing the operating wavelength of the quarter-wave transformer) lowers the antenna tuning frequency.
- Reducing the length of the “S” element (or, the same thing, reducing the operating wavelength of the quarter-wave transformer) increases the tuning frequency of the antenna.
After final tuning of the antenna at the upper operating frequency, it is useful to check the antenna parameters at its lower operating frequency. As you can see from this description, tuning the Open Sleeve antenna to a single band is relatively easy. But setting up a 3, 4 or 5-band antenna is no longer such an easy task. The “S” elements influence each other and the “M” vibrator, and by tuning the antenna in one of its upper operating ranges, the resonant frequency of the antenna in other ranges will also change. And yet, with persistence, it is quite possible to configure the Open Sleeve antenna to operate on 3 and even 5 bands!
In table Figure 3 shows data for the implementation of the Open Sleeve antenna for amateur bands 2 and 3. These antennas were designed by radio amateur UA3AVR. In Fig. Figure 17 shows antenna designs that explain Table 3.
Table 3. Open Sleeve Antenna Implementation Data
