Subsequent testing with a scanning receiver in the specified frequency range (145 MHz) near the transmitter did not produce any results. Previous work for two years in the same place and with the same equipment did not cause any complaints, and there was only one difference - a different antenna: before the incident - a “double square”, then - the described EA. The radiated energy of the two-watt transmitter turned out to be so concentrated in the direction of the main lobe of the antenna radiation pattern that it became equal in level to the signal in the main (not mirror) channel of the “commercial” receiver, where reception of the two-meter range transmitter signal became possible exactly as if the transmission was carried out at a frequency 2Ff higher.

I ask radio amateurs to pay the most serious attention to this problem: although it is indeed “not yours,” you will have to eliminate it. since businessmen (and others like them) don’t care about this: they “paid money” and you can’t force them to fork out for an additional high-pass filter or bandpass filter.

After carrying out some measurements, the author (out of harm’s way) decided to transfer experiments with EA to field conditions - to the dacha. Since the antenna weighs little and is very easy to roll up and unfold, there are no problems with transportation. A few words about why the “square” was chosen as a portable antenna. Firstly, it is half as long as, for example, a dipole antenna (in terms of the length of the elements). Secondly (and this is the main thing), the “square” can be operated at very low suspension heights and is insensitive to surrounding objects (the influence of a hand brought to the antenna from the side affects only a distance of less than 150...200 mm). Thirdly, such an antenna to a certain extent suppresses local noise and impulse interference. Fourthly (in the author’s version), it has a closed DC active element.

The basis for the construction of the EA was a “double square” [1] fed by a 75-ohm cable with a distance between vibrators of 0.2 (see Fig. 1), the elements of which (1 - active vibrator, 3 - reflector) were simply suspended on the window window 2 inside the room.

Such a “window”-traverse can be mounted using hinges on the wall of the house or the corner of the balcony. Rotation of such an antenna, depending on the location of the reflector, is possible within 120...150°. Hooks and loops can be used to secure in the chosen direction. Such a design, of course, taking into account specific local conditions, can be convenient both for communications and for television reception.

How did the described EA begin? In the room (a room on the second floor of a wooden house) a “stand” was made for experimental work with VHF antennas: two pieces of thick fishing line were stretched under the ceiling at a distance of 250...300 mm from one another. Elements were hung from them using rings from the same scaffolding or winding wire (Fig. 2): first two, then three, and so on up to 13 (that’s how much the room could accommodate). The lengths of the active vibrator (AB) and reflector (P) elements were calculated using formulas from [1], and then checked using a measuring device frequency characteristics(ICH) XI -48. The directors (D1 - D11) are made with a decrease in each subsequent one (per side) by 5 mm. The material for the manufacture of elements is aluminum wire in polyvinyl chloride insulation from a three-phase APV cable (even better - copper-plated aluminum wire

Rice. 3

in the same insulation, which can be soldered). The insulation was not removed from the wire (it is convenient to alternate elements with white, black and red insulation - it is easier not to confuse them during adjustment operations: after two elements the difference in size becomes more noticeable). The lengths of the sides of the frames and the distances between them are shown in Fig. 2 (the values ​​of their perimeters are given in parentheses).

The antenna input impedance is about 45 Ohms. For nutrition, the author used a segment coaxial cable RK-50 with a diameter of 4 mm and a length of approximately 1 m (Fig. 3). At the point of connection to vibrator 1 there is a ring 2 with a diameter of 20 mm made of 20HF ferrite, on which one turn of cable 3 is made. You can also use gamma matching (Fig. 4), which will allow you to match the antenna more accurately and, optionally, as with 50 - and with a 75 ohm cable. You can also move the first director relative to the active vibrator for coordination, and then tighten the remaining directors.

It should be noted that antennas with a large number of elements must have a rigid structure - the distances between the elements should not change during operation. As experiments in the field have shown, two sections of scaffolding are not enough: the slightest breath of wind - and the antenna began to “play” - the elements swayed like laundry on a line. Best option- a rigid traverse, but for traveling conditions this is undesirable, so I propose a design schematically shown in Fig. 5: add two more pieces of 1 fishing line or strings for tennis rackets, i.e., bring their number to four. The segments should be stretched at the corners inside frames 2 and secured (after final adjustment), for example, using the same scaffolding (3), at the required distance from one another in accordance with Fig. 2. The length of the scaffolding sections must be selected in such a way that 3...4 m are left on each edge of the antenna for tying to supports, for example, to trees.

To increase reliability, you can place frames 2 (Fig. 6) made of wooden slats at the edges of the structure, attach the ends of sections of scaffolding 5 to them in the corners, and stretch the antenna beyond the frames using, for example, nylon strings 3 (here 1 - supports , 4 - antenna elements). If a trench is made from wooden blocks 4 on one or both frames (Fig. 7), then the antenna vibrators 3 and guy wires 2 can be placed in them as if in a case in a folded state and in this form the antenna can be stored and transported to any distance. To attach the cover frame 1 to the frame 4, you can use hooks or rings of electrical tape. In this case, the power cable can be laid together with the antenna around the perimeter of the frames or disconnected (if there is a detachable connector).

Antenna elements should be made of well-straightened wire. The easiest way to do this is by pulling it out, securing one end in a vice and holding the other in pliers. When cutting off workpieces, it is necessary to provide allowance for connecting (twisting or welding) the ends of the wire, for which they should be freed from insulation. A small “tail” of twisted wires does not affect the operation of the antenna; it is only important that the calculated perimeters of the frames be observed. It is better to place the connection points of the elements on one side, for example, from the bottom. There should be no distortions in the plane of the frames. They should be installed relative to one another strictly parallel and “concentrically” (when viewed from the side of the reflector). You can orient the antenna to clarify the direction towards the correspondent as shown in Fig. 8, i.e. holding it by

wooden frame 5 (or guy 6) behind the reflector - in this case, the influence on it from the operator is minimal. It is advisable to tie the guy wire 2, attached to the wooden frame 3 on the side of the directors 4, to the supports 1. Having found the correct direction towards the correspondent, it is better to tie the frame at the corners - the antenna will spin less in the wind. The experiment with EA (with vertical polarization) was carried out in close proximity to the ground, in a drained swampy area, in a lowland. The upper parts of the antenna elements were at a height of 1.8 m. The antenna was stretched between the wall of the barn and a small board dug into the ground as a support and reinforced with a gusset on the antenna side. The distance to the correspondents reached 22...24 km. In the “target” EA there was a road running along an embankment and dividing the “target” in half, about 200 m to the road, and behind it there was a forest 350...500 m (the situation is schematically depicted in Fig. 9).

With careful manufacturing and rigid design, the EA “spot” outlined by the main lobe of the radiation pattern (at a level of 0.7) is 25...30°. If the elements are not clearly installed, the “spot” is blurred and the gain decreases. If it is not possible to ensure the mechanical stability of a multi-element antenna (the EA scaffolding is quite rigid on four sections) and sufficient precision in its manufacture, it is better to limit yourself to four or five elements, and to manufacture them take a wire of a larger diameter. In this case, the antenna will have to be raised higher to avoid reflection from the ground near the antenna due to the expansion of the main lobe of the radiation pattern. However, the elements will still have to be fastened quite rigidly.

When working in the forest (especially with vertical polarization), you should choose sparse or open places towards the correspondent (even better - elevated ones), hanging the antenna between trees or supports in such a way as to avoid the presence of trees in the “target” of the antenna close to it. So, the described EA can fold and unfold like the bellows of a harmonic. This is convenient for rolling, carrying and then quickly unrolling, but is only suitable for relatively slow turning. However, if you prepare everything in advance (hooks for fastening, for example), then the antenna can be rotated by two people in ten seconds, which allows you to use it in “Field Day” competitions on the road. 13-element EA was calculated for

Fig.7

operation at a frequency of 145.5 MHz. With a little adjustment, or even without it, the antenna can be used throughout the entire two-meter amateur band. EA gain - no less than 15...16 dBd. The width of the main lobe of the radiation pattern in both the vertical and horizontal planes is no more than 30° (at level 0.7). Input impedance - about 45 Ohms, SWR at a frequency of 145.5 MHz when using RK-50 coaxial cable and matching device, shown in Fig. 3, - 1.8.

The methods used by the author to evaluate the quality of the antenna are amateur and approximate. During the experiments, foreign equipment was used: IC-706, FT-11, FT-270. At a distance of 24...25 km with a low suspended EA and a power of 0.3 W, correspondents gave maximum ratings of 3-4 points on the scales of the available S-meters. For comparison: in their equipment the noise suppressor “opens” and “holds” and the signal intelligibility is 100% at signal levels when the S-meter shows nothing at all. But it is known that with an auditory test, 1 point means reception is impossible, so the signal level in the city turned out to be significant even with such a low power. When increasing it to 4 W, the maximum ratings were 59, 59+10 and even 59+20 dB! True, the last “decibels” sometimes “blinked”. The experiment was carried out in FM mode. For reception in the city, a vertical dipole, a four-element collinear antenna and a vertical five-element “wave channel” located on the roofs of houses were used, and at the far (from the EA) end of the city the “wave channel” stood “slightly sideways”.

The influence of the wet earth's surface and vegetation on the passage of the signal near the ground was noticed. As soon as the rain stopped and the sun came out, the signal strength dropped by 2 points. The ratio of signal levels between the standard F-11 “rubber band” and EA was estimated: only “change in the noise spectrum - reception is impossible” - to 59 decibels, which clearly speaks in favor of EA.

A "wave channel" antenna at such a low altitude would be hopelessly out of tune. The large linear dimensions of the elements of such an antenna require greater care in operation and a higher suspension height, which is not always possible. Although when walking, it’s probably more convenient to carry “Yagi” in a folded state, for example.

You can experiment with VHF antennas, as mentioned above, on a “stand” of two stretched sections of scaffolding. Elements of dipole antennas, for example, are simply placed on top and moved relative to each other during tuning. They can be secured against accidental displacement with some kind of clamps, for example, plastic clothespins with cuts. As a reference, you can use the “beacon” signal [3], installed in the antenna “alignment” in the center of the main lobe of the radiation pattern at a distance of at least 10 traverse lengths (the distance from the reflector to the last director). The cable from the active vibrator is connected to the input of the receiver, the setting is carried out according to the maximum signal of the “beacon”. In the same way, you can “work out” a directional antenna for receiving television signals beyond the zone of reliable reception. In this case, the cable from the antenna is connected to the TV, and the settings are carried out, achieving

maximum contrast and minimum noise (moire) on the screen, or better yet, by controlling the AGC voltage. The setup sequence is as follows. First, the scaffolding-traverses are pulled in the direction of the television center, the active vibrator is suspended and connected to the TV. Then a reflector is installed behind the vibrator and moved along the traverses until the maximum possible signal level is obtained (perhaps this will just be an increase in noise in the audio channel). Having secured the reflector in the found position, install the first director and in the same way achieve a further increase in the signal, then the second, etc. until the last director.

Next, the direction to the television center is clarified by turning the traverses on the side of the reflector, after which the position of all antenna elements is once again adjusted to the maximum of the received signal. In a similar way, the author made a ten-element antenna on the sixth TV channel for receiving transmissions in the mountains of Karachay-Cherkessia (the signal reflected from the mountain was received). Due to the lack of suitable material, the active vibrator had to be cut out of a sheet of duralumin (Pistolkor's vibrator).

mount the coaxial connector plug for connection to the antenna socket of the radio station.

It is easy to change the polarization of the antenna by turning only the active vibrator 90° (there is no need to touch the other elements). Some inconvenience in this design is the lack of cable weight compensation for vertical polarization. If the length is short, there are no problems - the operator holds the cable himself, but if it is long. the length has to be supported by an additional slingshot stuck into the ground near the active vibrator. It is advisable to position the cable perpendicular to its side (with vertical polarization, it should be positioned strictly horizontally). The author hopes that the simplicity of the design and manufacture of the described EA will encourage radio amateurs to carry out their own experiments with antenna technology, because it is known that best amplifier RF is a good antenna. Such an antenna will allow you to feel much more confident on a hike, at the dacha, in a word, wherever you need to provide reliable low-power communications over long (by VHF and QRP standards) distances. After all, low power means small dimensions of the equipment itself and, most importantly, its power sources. Remember the test results given above: only a change in the noise spectrum to the standard antenna of the radio station at an output power of 4 W and 3-4 points on the “coarsened” S-meter at 0.3 W - the difference is significant!

The antenna is called experimental - the radio amateur himself will decide how best to make it from available materials. In the traveling version (without wooden frames or a case and cable), it weighs less than a kilogram, is easy to carry - you can carry both the antenna and the bag (inside the vibrator frames) with one hand, and the ends of the traverse can be easily gathered into a bundle and temporarily secured with PVC rings electrical tape or KLT. The antenna can be located next to it (on the side) at a distance of up to 150...200 mm, which, in turn, allows the use of a short cable length. Equally important is that it works normally at low suspension heights (although a higher height, if circumstances permit, will not hurt at all). In practice, the top edge of the vibrators should be at a height of at least 1 m (preferably 1.5...2 m) from the ground. The distances between the vibrators are selected taking into account their easy memorization, which simplifies the manufacture of the antenna as needed (impromptu), as well as if it is necessary to adjust the position of the vibrators when they are accidentally displaced.

It should be taken into account that when using uneven (untrimmed) wire to make frames, an error occurs, which is expressed in the lengthening of the perimeter of the elements. The use of thicker wire leads to an increase in the intrinsic capacity of the frames, which requires a corresponding reduction in their perimeter. Approximately the bandwidth F (in megahertz), which increases with increasing diameter of the frame conductor (including in the form of a tape), can be calculated using the formula given in [I]. For example, for an active vibrator F - Рmax - Fmin - 304635/Рmin - 304635/Рmax, where Fmax and Fmin are the upper and lower limit frequencies of the passband, corresponding to the minimum and maximum frame perimeters (Fig. 10).

A ribbon vibrator can be modeled from several wires by electrically connecting them to each other (Fig. 10, b), which has long been successfully used in the manufacture of zigzag television antennas. Sometimes, when making an antenna according to the description, it is better to slightly increase the diameter of the wires of the elements, and thus “stay” in the passband, losing somewhat in the antenna gain.

Taking this opportunity, I would like to express my gratitude to those who provided (willingly or unwittingly) assistance to the author in the experiment: RA9LO, RA9LZ, RA9LE, UA9LFJ, RA9LT, UA9LAJ.UA9LP, UA9LDG, RA9LY. UA9LAC, UA9LR, RA9LAP, UA9LBG, as well as radio amateurs of the Sverdlovsk region who installed a repeater (IARU R1 channel 145025 kHz - TX / 145625 kHz - RX) and prompted me to this venture. After long vigils during experiments with EA, I still managed to detect unclear signals from the S2 QSB repeater. But, naturally, two watts were not enough for transmission (QRB 300 km) to open the repeater. It was necessary to make a sound generator of sinusoidal oscillations using an electromechanical AF filter with a frequency of 1343 Hz and a bandwidth of 9 Hz (SHY2.067.064 according to the specifications of the Kama-S radio station), so that when the repeater was “opened” by Sverdlovsk stations, a voice could “crawl through” in the background of the voice. weak telegraph signal.

But it was not there. It takes time and an excellent passage, which happens “only once a year,” for example, like in November 1996, when the World Cup worked with the Sverdlovsk team directly, without repeaters. In the meantime, using FM telegraphy and pressing on the vocal cords, I was only able to reach our “firms”. They appreciated the quality of my EA and called the Gossvyaenadzor control point, since the level of my signal (in the direction of Yekaterinburg, and during experiments - in other directions) compensated for the suppression of two-meter frequencies amateur band input circuit of their receiver (suppression of the mirror channel). The experiment had to be stopped.

A few words about other experiments with loop antennas. Tests of a two-element “double square” have shown that for communication within the city it is suitable as an “omnidirectional” antenna with vertical polarization with a transmitter power of 1...5 W. Being installed higher above the roof, it “reaches right to the ground” in any direction, both during reception and transmission (the author’s experiments with UA9LFJ). The acquisition of omnidirectional properties by the antenna is explained by re-emissions and reflections, for example, from buildings, wires, metal poles and other structures.

When using such an antenna on the edge of the city, its radiation pattern comes into force, having a fairly wide (approximately 60° at the 0.7 level) main lobe and a gain of about 8 dBd (with the reflector located at a distance of 0.2 from the vibrator and an input impedance of 75 Ohms ). Thanks to this, there is no need to turn the antenna, just point it at the city.

As you move away from the city, the latter occupies a smaller and smaller angle on the horizon, and the signal level drops in proportion to the square of the distance, which corresponds to a narrower main lobe of the radiation pattern (higher gain) for antennas with an increased number of elements.

A seven-element EA located inside a wooden shed was also tested. The width of its main lobe turned out to be approximately 40°, and the gain was about 12 dBd.

As it turned out, the effect on the configuration of the active element (in terms of resonant frequency and input resistance) on the part of the fourth and subsequent directors can be ignored and their number can be selected according to need. It should not be forgotten that when large number Directors, although it is possible to concentrate energy to a small “spot”, it does not take long to “miss” in the direction of the correspondent both in azimuth and elevation. In the same time multi-element antennas able to work at lower altitudes. An increase in the signal by one point was noted when the EA was raised from the initial height by only 300 mm. When the polarization changes to horizontal (for the correspondent it is vertical), the signal strength drops by four points. More precise matching of the feeder with the antenna can be achieved by moving the ferrite ring along the cable.

Some lowering of the middle elements of the EA and raising of the last directors (due to sagging of the traverse from the scaffolding), as well as suspension of the upper sides of the elements at the same level (aconcentric) creates additional conditions to a slight elevation of the main lobe of the radiation pattern. This also facilitates the ability to hang low above the ground without the risk of reflection and scattering of concentrated RF energy near the antenna. At the same time, the conditions for the distribution of this energy over the very surface of the earth remain within the opening of the main lobe,

Literature

1. Rothhammel K, Antennas. M.: Energy, 1979. S. 267, 268.
2. Rothhammel K. Antennas. M.: Energy, 1979. P. 232,233.
3. Besedin V. VHF Beacon. - KB magazine, 1998, N 2, pp. 46,47.
4. Besedin V. Adaptation of industrial radio stations to amateur conditions. - Radio amateur. KB and UKV., 1996, N 6, p. 26.

Vertical half-wavelength emitters with asymmetrical power supply, located above a small metal screen located near the earth's surface, have better parameters than quarter-wavelength emitters. I wanted to check in practice how significant this difference is when conducting local radio communications in the VHF range.

Along with other car antennas in the CB range (27 MHz), I received an antenna with the trade name “Cobra”, which served as the basis for the design of a VHF antenna in the range 144...146 MHz. Its emitter was distinguished by increased elasticity, and the length was more suitable to the calculated one. Measurements made to detect any resonance of an antenna with an acceptable SWR in the range from 26 to 175 MHz did not yield results. This and similar “Hustler” antennas, despite their relatively low cost, are not in great demand. Due to the small area of ​​the mounting magnet, they do not adhere well to the car body and fall off in strong winds or sudden shocks. In addition, drivers, trying not to scratch their car, additionally stick tape or cloth on the base of the antenna. And since through the base there is a capacitive connection between the antenna matching device (ACU) and the car body, this leads to a change in the resonant frequency of the ACU and loss of signal power during transmission and reception.

After simple modifications, the antenna is suitable for operation in the 2 meter range. Since the length of its emitter, weight and windage are reduced, the antenna has sufficient mechanical stability. The antenna design is clear from Fig. 1.

The length of the emitter was specified during the setup process. The circuit and design of the antenna matching device are shown in Fig. 2 and fig. 3

The installation was carried out on a standard getinax frame with a diameter of 16 and a length of 23 mm. Coil L1 is wound with PEV-2 wire with a diameter of 1 mm. The winding pitch is 3 mm, the number of turns is 3-4 (to be specified during the setup process). Bronze threaded rods 2 with M8 threads are pressed into the ends of the frame 1 (Fig. 3), which serve for fastening the emitter and the magnetic base of the antenna. These studs have additional fastenings in the frame in the form of bronze transverse studs, to which the leads of the ACS elements are soldered. On the side surface of the frame there is an additional insulated support contact, which also serves for mounting the elements.

The capacitance of capacitor C1 was selected experimentally. First a variable capacitor was installed small capacity with an air dielectric, which was later replaced by a permanent ceramic one. Capacitors KD-1 or KT-1 and similar ones with low or zero TKE and rated voltage not less than 250 V. This is necessary even when using VHF radio stations with a transmitter output power of no more than 10 W.

After the final setup of the ACS, the coil terminals should be firmly secured to the frame, and all joints of the parts and the power cable should be well soldered. The capacitor must be coated with a layer of good moisture-resistant varnish, and also ensure good protection parts of the entire device from moisture penetration.

In Fig. Figure 4 shows a graph of the antenna SWR as a function of frequency, Fig. 5 - a fragment of her appearance.

The antenna has been used with a mobile car VHF radio station for more than two years. During the initial check of its work, several dozen two-way radio communications were established with correspondents located in different points of our region, on different distances and height relative to the location chosen for the experiment. Most correspondents noted an increase of about one point in the signal level (as measured by the S-meter) compared to the quarter-wave GP antenna used in this experiment.

You can make such an antenna yourself, if you have a suitable ring magnet and a metal spring wire of a suitable diameter with good conductive properties for making the emitter. The metal base can be turned into lathe, drilling an axial hole in its center for attaching the automatic control system.

The antenna of the UA9GL design has proven itself well and competes even with more complex antennas when conducting radio communications, both through troppo, aurora and through EME. The antenna has a gain of about 17-18 dB relative to the dipole and is considered one of the best antennas.

The antenna is easy to build, practically does not require any additional costs, and everything is clearly clear from the drawings. The materials used here can be replaced with similar ones in compliance with the naturally recommended dimensions. The power cable for this antenna is a common 75 ohm one. All antenna dimensions are shown in Fig.1. At the top are the dimensions of the lengths of the antenna elements, and at the bottom are the distances between them.

Figure 2 shows the dimensions of the active vibrator; the main requirement for the vibrator is that the ratio of the upper to lower diameters should be equal to 3.

In our example, top = 6 mm and bottom = 2 mm. The ends of the wire must be inserted inside and well secured there, soldered, and crimped to obtain reliable contact. The material for production can be anything from duralumin to copper, brass, it all depends on local capabilities.

Figure 3 shows the attachment point for the active vibrator and its attachment to the antenna boom and its connection to the antenna cable. The vibrator is isolated from the antenna boom. The material for making the insulator can be anything from fluoroplastic to textolite.

Figure 4 shows the attachment point for all passive vibrators of the antenna and reflector. After the vibrator is securely fastened with an M3 screw in the body of the insulator, it is necessary to cut off the head of the M3 screw. The material for the manufacture of the reflector and passive antenna vibrators can be anything than indicated in the figure, but the diameter must remain as indicated - 4 mm.

Figure 5 shows correct connection 75ohm cable with

U- elbow whose length is 680 mm.

If you want to work through the Moon, etc., where you need to have the petal pressed to the horizon, then you need to use Fig.6. The figure shows the dimensions for matching antennas located on 2 floors. A 75 ohm cable is used everywhere, with the only exception: in order to match the supply 75 ohm cable and the connection point of the upper and lower floors, a transformer is needed, the role of which is played by a piece of 50 ohm cable equal to 337 mm in length. The distance between the antennas should be from 3.6 to 4.0 meters.

But if you want to create more good antenna then you should pay attention to Fig. 7, which shows a connection diagram of such antennas according to a 2x2 scheme. IN this option the entire cable feeding the antenna is 75 ohms.

The distance between adjacent rows is 4.0 meters, and between floors is from 3.6 to 4.0 meters.

In any embodiment, the manufacturing of a single antenna or they will be connected in groups, it is necessary to ensure the wind rigidity of the structure.

Figure 8 shows an example of how to ensure rigidity in a single version of manufacturing due to stretch marks from a cable broken by nut insulators in the horizontal and vertical planes.

Good luck with the manufacture of this antenna and see you on 144 MHz.

Antennas 144 MHz ANTENNA
The development of local FM networks in the 144 MHz band and the increasing proliferation of repeaters has led to increased interest among radio amateurs in omnidirectional antennas with vertical polarization. In addition to the classic quarter-wave rod (GP), an antenna with a radiator length of 5/8 L is very often used. With such an antenna, the radiation pattern in the vertical plane is pressed to the ground, which helps to increase the communication range. Moreover, compared to the GP, the 5/8L antenna has a gain of 3 dB.
The Korean magazine KARL Monthly (1996, April, p. 55-56) published a brief description of the VHF antenna, which is a common-mode radiator made up of two 5/8L antennas.
From general considerations, it can be argued that such an antenna, with completely acceptable dimensions (full height with a mast of approximately 3 m), has even greater gain than a single 5/8L compared to GP. The described version of the antenna is used by the United States Navy (USN STAR GP ANTENNA VHF) and has an operating frequency band of 120...158 MHz with a SWR of no more than 1.3.

The antenna is shown schematically in Fig.
1. The upper vertical emitter is fed through a phase-shifting line. At an angle of 45" two additional emitters are connected to the lower vertical emitter, which expand the operating frequency band. Two counterweights are also located at an angle of 45° to the vertical emitters and have a length of approximately 5/8L. The antenna matching element with the 50-ohm feeder is circuit L1C1.
The design of the antenna is shown in Fig.
2. The upper and lower emitters are connected by a dielectric insert, onto which a phase-shifting line is wound. The phase shifting line is made of insulated copper wire. The diameter of the wire is not indicated in the article, but for general reasons it should be as large as possible (as long as the line fits on the frame). The triangular shape allows it to be wound onto a dielectric frame turn to turn. There is also a dielectric insert between the lower end of the lower emitter and the 1 m long metal mast (the counterweights are not electrically connected to the mast).

TO ENLARGE (REDUCE) THE DIAGRAM, CLICK ON THE PICTURE

Counterweights and a dielectric insert are sandwiched between three-lobe parts (see Fig. 2). Additional lower radiators and counterweights are composite. Attached to the three-lobe parts are sections of pipes with clamps, which include emitters and counterweights, which are made of pipes of smaller diameter. This makes it possible to change their length during the process of tuning the antenna. The reel is frameless. It is made of bare copper wire with a diameter of 1.5 mm and has two turns with an internal diameter of 16 mm. The capacitance of capacitor C1 is 5...10 pf.
Since the antenna is factory-made, the vertical emitters have a variable diameter. At the lower pipe, in particular, it varies from 19 to 16 mm (see Fig. 2). In an amateur design, you can, of course, use a regular pipe with a constant diameter.