Do-it-yourself decimeter antenna. UHF band antenna. Theoretical basis. Practical execution

10.10. UHF Antennas

In the AMV range, due to a decrease in the effective length of the receiving antenna, with increasing frequency, a lower voltage develops at the antenna input than under the same conditions in the meter range. Therefore, it becomes necessary to install antennas with a high gain. In antennas of the "Wave channel" type, this is achieved by increasing the number of directors, creating in-phase arrays from multi-element antennas (Fig. 10.30). Since the dimensions of the antenna elements of adjacent channels differ slightly, they are usually given for a group of channels (Table 10.20).

Table 10.20

13-element antenna type "Wave channel" consists of three reflectors, an active loop vibrator and 9 directors. The distance between the ends of the loop vibrator A is 10...20 mm. The diameter of the antenna vibrators is 4...8 mm. The antenna gain is 11.5 dB, the opening angle of the main lobe of the radiation pattern in the horizontal and vertical planes is 40°.

19-element wave channel antenna for the UHF range (Fig. 10.31) consists of three reflectors, an active loop vibrator and 15 directors. The vibrators are made of wire and tubes with a diameter of 4 mm. They are attached in any way to the carrier boom with a diameter of 20 mm. The boom length for any channel group is 2145 mm (Table 10.21). The antenna gain is 14...15 dB, the opening angle of the main lobe of the radiation pattern in the horizontal and vertical planes is 30...32.

Broadband antenna of the "Wave channel" type for reception in channels 21 ... 41(Fig. 10.32).

Depending on the distance to the television transmitter and the zone of reliable reception of its signals, the number of elements (directors) of the antenna can be reduced to 8.11 or 15.

In the case when preference is given to reception in one television channel (for example, reception of an NTV program from Kolodishchi), the dimensions of the antenna elements and the distances between them can be recalculated for this channel.

Table 10.21

The UHF broadband antenna has the highest gain (13 dB) in the 28th channel, the average frequency of which is 500 MHz. The conversion factor (Kp) in this case is determined by the formula

Kp=530/fcp

where fcp is the average frequency of the UHF channel, MHz. For the 37th channel, the average frequency of which is 562 MHz, Kp is equal to:

Kp=530/562=0.943.

Multiplying the dimensions of the elements and the distance between them by 0.943, we obtain the dimensions of the antenna for the 37th channel (Fig. 10.33). You can also recalculate a broadband antenna for any channel (or group of channels) of the UHF. The average frequency of the channel (group of channels) is given in Table. 10.2, the length of the half-wave loop - in table. 10.1. When using a metal carrier boom (traverse), the dimensions of the elements obtained during recalculation are increased by half of its diameter.

The gain of the channel antenna increases to 14...15 dB. An antenna of eight elements is used at a distance of up to 20 ... 30 km from the village. Kolodishchi, from 11 - up to 30 ... 40, from 15 elements - up to 50 ... 60 km. Behind the zone of reliable reception at a distance of up to 70 ... 90 km, an antenna of 24 elements is used. To provide good quality of the received image, an antenna amplifier is installed directly on the mast.

The antenna is little influenced by nearby objects and has good repeatability. Deviations of up to 2 mm from the calculated dimensions are permissible with virtually no deterioration in the antenna parameters.

Antenna type "Wave channel" with a complex passive reflector(Fig. 10.34; tables 10.22 ... 10.24) consists of a lattice reflector (Fig. 10.35, a), two sheets of which are installed at an angle of 90 ° at the end of the carrying boom, an active loop vibrator (Fig. 10.35, b) and 18 directors.

At the same time, the first two directors (A1 and D2) are two-story and spaced vertically by the thickness of the carrier boom (Table 10.23).

Table 10.22

The main advantage of such an antenna is the reliable screening of the rear hemisphere due to an increase in the coefficient of protection when installing a complex reflector. The latter concentrates the energy of the useful signal in the direction of the active vibrator, which helps to increase the gain of the antenna.

Table 10.23

Table 10.24

On fig. 10.36 shows a side view of the antenna described above. The 6-element antenna is designed for short-range reception at a distance of up to 10 ... 15 km from a television transmitter:

10-element - 15...25; 15-element - 25...40; 20-element - at a distance of 40 ... 60 km or more.

In the UHF range are widely used loop Antenna Triple Square, the frames of which are made of a single piece of copper, brass wire with a diameter of 2 ... 3 mm. With the dimensions of the decimeter range (Table 10.25), the antenna has sufficient rigidity. The wire must be bent in a certain way (Fig. 10.37). At points A, B and C, the wires must be stripped and soldered. In this design, instead of a train (see Fig. 10.12), made from a piece coaxial cable, a quarter-wave short

a closed bridge (see Fig. 10.11) of the same length as the loop (see Table 10.5). The distance between the bridge wires remains the same (30 mm). The design of such an antenna is quite rigid, and the lower boom is not needed here.

The feeder is tied to the right wire of the bridge from the outside. When the feeder approaches the vibrator frame, the cable braid is soldered to point X "the central conductor is to point X. The left wire of the bridge is fixed on a dielectric stand or, in the case of an external antenna, on a mast. It is important that there is no feeder and mast stand in the space between the wires of the bridge .

In the presence of copper, brass or aluminum strips

can be done diamond-shaped antenna(Fig. 10.38). The strips (1) are overlapped with screws and nuts. There must be reliable electrical contact at the point of contact between the plates. The thickness of the strips is arbitrary.

A diamond-shaped antenna can operate in the frequency band of channels 21 ... 60, its gain is 6 ... 8 dB. To increase it, the antenna can be equipped with a reflector (Fig. 10.39).

The simplest reflector is a flat screen made of tubes or pieces of thick wire. The diameter of the reflector elements is not critical (3...10 mm). The reflector sheet (2) is fixed with the support stands (3)

Table 10.25

to a metal or wooden mast (4). Points 0 have zero potential, relative to the ground, so the posts (2) can be metal.

Feeder (5) - a RK type cable with a wave impedance of 75 Ohm is laid to power points A and B. The cable braid is soldered to point B, and the central conductor to point A. At long-range reception, the diamond-shaped antenna can be equipped with a broadband amplifier (6).

2-element Swiss antenna(see Fig. 10.21) can also be used in the UHF range (Table 10.26).

The article is devoted to an antenna suitable for various conditions for receiving a television signal: city, open space, long-range reception. The design of the antenna has proven itself well when receiving an analog television signal for three years. Excellent results are obtained when receiving digital TV broadcasts.

The quality of television reception depends on many factors. In the conditions of the city, the interaction of the main wave of the television signal and the reflected waves is negligible. With direct visibility between the receiving antenna and the transmitting antenna, the main wave and the waves reflected from the ground, squares, streets, roofs of buildings come to the receiving point. For radio waves, a large modern city is, figuratively speaking, a heap of “mirrors” and “screens”, which are bridges, factory pipes, high-voltage lines. High-rise buildings, like a passive repeater, re-radiate waves from the transmitting antenna. The nature of the propagation of radio waves is very complex, even near the transmitter. In the radio shadow of obstacles, a weakened useful signal is received, reflected signals, noise and interference become more noticeable. In wet walls of houses, in wet trees, the signal is weakened more strongly. The maximum attenuation of the signal received by an antenna located in the radio shade of trees occurs in summer. The addition and subtraction of the main and reflected radio waves leads to the amplification of some television signals and the attenuation of others.
Loop antennas in these conditions give good results due to the reduction in reception in the lateral and reverse directions, they are less susceptible to electrical interference and, in particular, interference from the ignition of internal combustion engines.
For long-range television reception, the most stable image is provided by loop antennas, one of which is described in this article.

Antenna parameters

Frequency range of received signals, MHz……530 - 780
Main received TV channel ….38
The range of received television channels ... 30 - 57
Polarization of received signals………horizontal

From a wide variety of loop antennas for the UHF range, a "triple square" antenna is often made. What if the gain of the triple square is not enough, and other antenna designs are not suitable for the range of television channels of interest? At the same time, there is absolutely no place to get a sufficient number of aluminum tubes of the required diameter and specific fasteners, there is no way to assemble and install an antenna, the dimensions of which are measured in meters. Can an antenna amplifier be used that will amplify the main wave of the TV signal along with the reflected waves received by the antenna? The solution to this problem was the combination of four triple squares into an antenna system - a phased array. The antenna gain far exceeds one triple square, and the dimensions are quite acceptable. The dimensions of the construction of one of the four triple squares are shown in the figure.

For the manufacture of a triple square, galvanized steel wire with a diameter of 3 mm is required. Galvanized is a wire that has a tin coating. Such wire is easier to solder and does not rust in the open air. It takes 2 meters of wire to make one triple square. The piece of wire must not have sharp bends, dents, scratches, rust or other defects. Before manufacturing the antenna, the wire blank is thoroughly wiped with a solvent. The wire is bent according to a pattern showing the construction of a triple square. The wire joints at the top of the squares are soldered. The sections of the wire at the joints are covered with a flux prepared from of hydrochloric acid by zinc etching. With a soldering iron with a power of forty watts, and preferably sixty watts, the sections are covered with fusible solder, as far as the power of the soldering iron allows. Then the joints are pulled together with one or two turns of tinned copper wire with a diameter of 0.6-1 mm and soldered again. Finally, the joints are well soldered over the gas stove burner using solder and rosin. The remaining rosin is removed from the resulting structure and washed off with a solvent. The solder joint should be well tinned, providing reliable contact and mechanical strength. Triple squares must not be painted or varnished.
Before combining the triple squares into a phased array, each one needs to be checked and adjusted. Checking and adjustment is carried out indoors. A television coaxial cable with a characteristic impedance of 75 ohms is connected to the triple square, as shown in the figure. The image on the TV screen when setting up the antenna in the room may be black and white with a lot of noise. Triple square adjustment is performed based on the least amount of noise on the TV screen. If one triple square does not give a color image - it does not matter, when combined into a phased array, the image quality will increase significantly. Having connected the triple square to the antenna input of the TV, it is necessary to find the point of soldering the cable to the lower vertical part of the antenna structure by moving the connection point vertically. When moving a connection central vein cable and cable screen must be connected at the same level. In one copy of the triple square best image on the TV screen can be obtained by soldering the cable almost at the closing horizontal section at the very bottom of the antenna, in other copies as shown in the figure in the third copies in the middle. Each triple square has its own optimal cable connection point. After finishing the setup and checking the triple squares, it is important not to mix up the cable connection points. To obtain a good quality of the antenna, 6-8 triple squares should be made, from which four giving the best results should be selected.
Triple squares, which are elements of a phased array, are connected by a coaxial cable. The basis of the antenna design is a wooden frame. The length of the vertical cable segments connecting two triple squares is selected experimentally. It is impossible to accurately determine the length of the cable segments in advance due to differences in parameters various types cable and unpredictable properties of manufactured triple squares.

Two triple squares are fixed by wrapping a PVC tube on one vertical frame element, which is a wooden block. In turn, identical pieces of cable 220, 240, 260.280, 300 millimeters each are connected to the triple squares. The opposite ends of the cable segments are connected to the screen-screen and core-core and connected to the cable going to the antenna input of the TV. The length of the vertical cable segments connecting two triple squares is selected according to the best image quality. The main contributor to the tuning is the length of the cable segments compared to the distance between the triple squares. When setting up, you can reduce or increase the distance between the triple squares, but this will not give much effect, so the distances in the design drawing between the triple squares are not given. The image on the TV screen should be better than when received on one triple square.

The frame is temporarily assembled from four wooden bars fastened together with a rope. Four triple squares are installed on the frame, connected by vertical cable segments. The length of two identical horizontal cable segments connecting the vertical segments with the cable laid to the TV antenna input is specified experimentally. For the final adjustment, two identical horizontal segments with a length of 130, 150, 170 or 190 millimeters are alternately soldered.
For the final manufacture of the frame, four wooden bars 8-11 millimeters thick, 60-70 millimeters wide, 520 millimeters long and three wooden bars of the same thickness and width 490 millimeters long will be required. The ends of the bars are coated with epoxy resin and dried for five days, then the entire surface of the bars is coated with epoxy resin and dried for five days. After coating with epoxy resin, wooden bars are painted with nitro paint at least twice. Before installing triple squares and cable segments that combine triple squares into a phased array, the first part of the frame is assembled from two vertical and two horizontal bars. The contacting surfaces of the bars are coated with epoxy resin, connected with screws and dried for at least three days. After the epoxy resin dries, the two screws connecting the upper horizontal bar with the vertical bars are unscrewed. Four screws securing the central horizontal bar remain.

Triple squares are installed on a wooden frame, connected by pieces of a coaxial cable. Triple squares are attached to the frame with several turns of PVC tubing. A cable is soldered to the antenna, going to the TV of the required length.

For correct phasing of the antenna system, the center conductors and screens of the coaxial cable segments are connected to triple squares in accordance with the phasing scheme. The end of the cable connected to the antenna is enclosed in a PVC tube with a diameter of 10-12 millimeters and a length of about three meters to protect the antenna cable from the weather. The PVC tube and cable are fixed with a thread on a horizontal bar. The soldering of the screen and the central core of the cable segments are isolated from each other with electrical tape. On top of the installed triple squares and cables, two vertical bars are installed, on top of them in the center is one horizontal bar. The frame parts are connected with screws with a diameter of 6 millimeters. When installing the screws, the holes left after unscrewing the screws connecting the upper horizontal bar with the vertical bars are used. Coaxial cable segments and parts of triple squares are enclosed within a wooden structure that reliably protects the solder points from the weather.

The gaps between the bars from the sides and ends are sealed using building sealant "liquid nails".

The antenna is mounted on the mast using clamps corresponding to the diameter of the pipe. Screws pass through the holes in the horizontal bars. The antenna is fixed at two points. By loosening the clamp screws, you can precisely orient the antenna to the transmitter.

Galvanized wire, pipe clamp, epoxy, paint can be purchased at a building materials store. Coaxial tv cable with a characteristic impedance of 75 ohms should be selected with a central core of copper and a double screen consisting of a foil and a braid of copper cores. Best results can be obtained by using the largest diameter cable with as many strands as possible in the shield.
The distances between the elements of the phased array, the dimensions of the triple square and the length of the cable segments are chosen through numerous experiments, in order to ensure reception is possible more TV channels and at the same time the smallest possible dimensions, reducing the mass of the antenna and facilitating installation. Reception on the antenna is possible through an obstacle from closely spaced trees. The antenna has a low windage. Cables are routed inside a sealed wooden frame for long life and impact protection. weather factors. The quality of the received image does not depend on the time of year and time of day.

Denisov Platon Konstantinovich, Simferopol

equipping country cottage area We try to make it as comfortable as possible for your stay. And this means that over time it acquires the amenities to which we are so accustomed in Everyday life– water supply, heating and, of course, electricity. And where there is the latter, sooner or later television will certainly appear. But how, you ask, to spend it in the country, if the purchase of an antenna, which, by the way, is quite expensive, is not provided for in the personal budget? Yes, very easy! A few basics of radio electronics, a couple of pieces of iron and a minimal soldering kit, and now, well tired in the garden, you are located on the country terrace to watch the evening news block.

Radio electronics and television: simply about the complex

The most important thing for any antenna is its ability to interact with a signal distributed over the air.

Currently, TV broadcasting is carried out in a single range - decimeter, and television transmitters cover almost the entire more or less populated area. This makes it possible to "catch" a TV signal anywhere.

But for this you have to take into account a few simple nuances.:

Based on this, among all the diversity television antennas The most affordable for self-manufacturing will be their types, such as:

All-wave (frequency independent)

It does not have high parameters, but it is the simplest and cheapest to manufacture - it is based on a metal frame, and ordinary beer cans or other tin containers act as receivers.

log-periodic range

Such an antenna can be compared to a fishing net that sorts prey when it is caught. This type antenna systems also has a simple design, but provides higher parameters than the all-wave.

Decimeter zigzag

For the decimeter range, the dimensions and complexity of the design of such an antenna are greatly simplified, and it can work in almost any reception conditions.

The subtleties of manufacturing television antennas

The elements of the antenna, through which the useful signal currents pass, are always connected by soldering or welding. But if the device will be placed outdoors, such as on a roof country house, such contacts will soon be corroded by corrosion.

If we are talking about a home-made antenna for giving, you should not strive for the ideal quality of contacts - if they rust or burst, then at least not soon. But it is desirable that the connections in the antenna design be as small as possible, which will provide stable and fairly clean reception.

The braid and the center core of the coaxial cable are currently made of inexpensive alloys that are resistant to corrosion. Unlike classical copper, they are difficult to solder. Therefore, care must be taken not to burn the cable.

For the manufacture of an antenna and its cable connection it is advisable to use:

Aluminum wire for the manufacture of antenna elements should not be used - it will oxidize very quickly and lose the ability to conduct an electrical signal. The best way copper or cheaper brass is suitable for this.

The antenna receiving area should be as large as possible. To do this, several metal rods of the same metal should be symmetrically attached to the screen - a frame that screens out ethereal and electrical noise.

Buying a simple signal amplifier that connects directly to the antenna will solve the problem with a weak and dirty signal.

As a result, the system will provide normal receiving power. All that is needed for this is to take the antenna to the roof of the country house and point it towards the nearest television tower.

Do-it-yourself frequency-independent antenna

The simplest all-wave is a pair of metal plates mounted on a wooden rail and connected by several turns of copper wire of any diameter. The width of such an antenna should be equal to its height, and the opening angle of the canvases should be 90 °. It is not necessary to solder the wire to the point of zero potential of the all-wave - it is enough to ensure its reliable fastening.

The frequency-independent antenna is capable of receiving both meter and decimeter signals from almost any direction. The disadvantage of this option is the unity gain and zero CPD - an indicator of the ratio of the signal power received to the main lobe of the antenna to the sum of the interference power at the frequency received by the other elements. That is why the all-wave is not suitable for receiving a TV signal in an area with strong interference or where the terrestrial signal is too weak.

To make your own frequency-independent antenna, you will need:

antenna cable;
several tin cans;
self-tapping screws;
plug;
insulating tape;
screwdriver;
wooden rail;
copper wire.

Banks are fixed on a rail (mast) with electrical tape at a distance of about 7 cm from each other.

Self-tapping screws are screwed into them, to the protruding ends of which the stripped ends of the antenna cable are screwed. The latter is fixed on the rail and laid along the external building structures of the country house to the place where you plan to put the TV.

You can improve the design of the all-wave oven by adding a few more sections from tin containers. After that, it remains to securely fix its mast in a vertical position, connect it to the TV and set up the tuner.

Another option for an all-wave antenna designed to receive a meter signal is a fan vibrator, which is popularly called a slingshot antenna.

Production of a log-periodic television antenna

The “speech therapist” antenna is a receiving line (a pair of metal tubes) with halves of linear dipoles perpendicularly connected to it - pieces of a conductor with a diameter of a quarter wave of the working signal. The length and distance between the latter changes exponentially.

For the manufacture of a log-periodic antenna, it is necessary to perform a number of calculations:

The beginning of the calculation of the length of the dipoles is performed from the second in length.
Taking the reciprocal of the progression index, the length of the longest dipole is calculated.
Then it remains to calculate the shortest - the first - dipole, and then, based on the selected frequency range, the length of the "zero" dipole is taken.

To achieve maximum receiving power, there should be a distance of 0.03-0.05 wavelength between the dipoles, but not less than twice the diameter of any of them.

The length of the finished LP antenna is about 400 mm. The diameter of the base of the LP antenna should be 8-15 mm, and the gap between their axes of the receiving line is taken no more than 3-4 dipole diameters.

For normal operation For LP antennas, you need to select a high-quality and fairly thick (about 6-8 mm in sheath) coaxial cable. Otherwise, you will not be able to compensate for the attenuation of the decimeter waves, as a result of which the TV tuner will not be able to pick up the signal.

The cable to the receiving line cannot be fixed from the outside, as this sharply reduces the quality of signal reception.

When installing such an antenna, you need to ensure its wind resistance, and if you use a metal pipe as a mast, you need to install a dielectric insert - a wooden block - at least 1.5 cm long between it and the receiving line.

It is possible to improve the design of the LP antenna by installing linear or fan-shaped hangers of a meter field on it. This system is called delta.

Antenna scheme "Delta"

Zigzag antenna for giving

The Z-antenna system with a reflector provides almost the same TV signal reception parameters as the LP antenna. However, its main lobe is horizontally twice as long. This makes it possible to catch a signal from different directions, which is especially true for rural areas.

The decimeter zigzag antenna has small dimensions, but its operating range is practically unlimited. The material for the manufacture of such a system is a copper tube or aluminum sheet with a thickness of about 6 mm. If you chose the latter, soldering it with ordinary solder or flux will not work - in this case, the fastenings are made with bolts. For outdoor installation, such an antenna will be ready only after sealing the connection points with silicone.

The design of the zigzag antenna consists of the following elements:

barbell;
wire cloth;
metal plates for attaching the canvas;
cross rails;
dielectric plates and gaskets;
mounting plate;
feeder line;
power plate.

Any of them can be made with your own hands from improvised materials or purchased at the nearest radio electronics store.

The sidewalls of the Z-antenna are made of all-metal or in the form of a mesh covered with a sheet of tin. When laying a coaxial cable along the body of the antenna, its sharp bends should be avoided. To do this, it is enough to reach the side capacitive insert and not let it go beyond it. At the point of zero potential, the cable sheath is carefully soldered to the web.

This class also includes such types of antennas as ring and reflex, which are also not particularly difficult to manufacture.

Options for self-manufacturing television antennas in the photo

There are other types of antennas suitable for self-production - wave, "Polish", simple frame and even primitive satellite ones. But whichever option you choose, a competent calculation of the parameters is required. The technique can be found in the technical literature on radio electronics. However, it is much easier and easier to ask advice from those who already have experience in the manufacture of this kind of antenna.

Self-made antenna for giving on video

Table 10.20

13-element antenna type "Wave channel" consists of three reflectors, an active loop vibrator and 9 directors. The distance between the ends of the loop vibrator A is 10...20 mm. The diameter of the antenna vibrators is 4...8 mm. The antenna gain is 11.5 dB, the opening angle of the main lobe of the radiation pattern in the horizontal and vertical planes is 40°.

19-element wave channel antenna for the UHF range (Fig. 10.31) consists of three reflectors, an active loop vibrator and 15 directors. The vibrators are made of wire and tubes with a diameter of 4 mm. They are attached in any way to the carrier boom with a diameter of 20 mm. The boom length for any channel group is 2145 mm (Table 10.21). The antenna gain is 14...15 dB, the opening angle of the main lobe of the radiation pattern in the horizontal and vertical planes is 30...32.

Broadband antenna of the "Wave channel" type for reception in channels 21 ... 41(Fig. 10.32).

Depending on the distance to the television transmitter and the zone of reliable reception of its signals, the number of elements (directors) of the antenna can be reduced to 8.11 or 15.

Table 10.21

The UHF broadband antenna has the highest gain (13 dB) in the 28th channel, the average frequency of which is 500 MHz. The conversion factor (Kp) in this case is determined by the formula

where fcp is the average frequency of the UHF channel, MHz. For the 37th channel, the average frequency of which is 562 MHz, Kp is equal to:

Kp=530/562=0.943.

The gain of the channel antenna increases to 14...15 dB. An antenna of eight elements is used at a distance of up to 20 ... 30 km from the village. Kolodishchi, from 11 - up to 30 ... 40, from 15 elements - up to 50 ... 60 km. Behind the zone of reliable reception at a distance of up to 70 ... 90 km, an antenna of 24 elements is used. To ensure good quality of the received image, an antenna amplifier is installed directly on the mast.

Antenna type "Wave channel" with a complex passive reflector(Fig. 10.34; tables 10.22 ... 10.24) consists of a lattice reflector (Fig. 10.35, a), two sheets of which are installed at an angle of 90 ° at the end of the carrying boom, an active loop vibrator (Fig. 10.35, b) and 18 directors.

At the same time, the first two directors (A1 and D2) are two-story and spaced vertically by the thickness of the carrier boom (Table 10.23).

Table 10.22

Table 10.23

Table 10.24

On fig. 10.36 shows a side view of the antenna described above. A 6-element antenna is designed for short-range reception at a distance of up to 10...15 km from a television transmitter: 10-element - 15...25; 15-element - 25...40; 20-element - at a distance of 40 ... 60 km or more.

In the UHF range are widely used loop Antenna Triple Square, the frames of which are made of a single piece of copper, brass wire with a diameter of 2 ... 3 mm. With the dimensions of the decimeter range (Table 10.25), the antenna has sufficient rigidity. The wire must be bent in a certain way (Fig. 10.37). At points A, B and C, the wires must be stripped and soldered. In this design, instead of a stub (see Fig. 10.12) made from a piece of coaxial cable, a quarter-wave short-circuited bridge (see Fig. 10.11) of the same length as the stub (see Table 10.5) is used. The distance between the bridge wires remains the same (30 mm). The design of such an antenna is quite rigid, and the lower boom is not needed here. -

In the presence of copper, brass or aluminum strips, you can make diamond-shaped antenna(Fig. 10.38). The strips (1) are overlapped with screws and nuts. There must be reliable electrical contact at the point of contact between the plates. The thickness of the strips is arbitrary.

A diamond-shaped antenna can operate in the frequency band of channels 21 ... 60, its gain is 6 ... 8 dB. To increase it, the antenna can be equipped with a reflector (Fig. 10.39).

The simplest reflector is a flat screen made of tubes or pieces of thick wire. The diameter of the reflector elements is not critical (3...10 mm). The reflector sheet (2) is fastened with the help of supports (3) to a metal or wooden mast (4). Points 0 have zero potential, relative to the ground, so the posts (2) can be metal.

Table 10.25

2-element Swiss antenna(see Fig. 10.21) can also be used in the UHF range (Table 10.26).

Table 10.26

Equipment for digital television- this is what you can buy in our store. Our company has been operating in the market of terrestrial and satellite equipment since 2003 and we already know most of our customers by sight.
For regular customers of our online store there is a system of discounts, which is calculated automatically according to the coupon number assigned to you personally.
All equipment undergoes pre-sale preparation, namely, it is installed latest version Software for satellite and terrestrial set-top boxes. All receivers are tested for performance.
Our company delivers equipment, both in Moscow and throughout Russia. Most courier companies have agreements for reduced shipping rates.
In our online store you can find almost any equipment that you may need to receive satellite and terrestrial television. We tried to make the ordering process convenient for anyone. If you plan to order more than one item, but several, then you can use the search in the store and pay attention to related equipment. If you want to pick up equipment for receiving satellite TV, then you should go to the tab menu " Satellite television", if for receiving terrestrial or cable TV, then "Terrestrial Television", etc. If you have questions during the ordering process, then you can use the online chat located on each page of the online store or order a call back.
We hope that in the digital TV online store you will be able to spend minimal amount time to order the required equipment.