How to make a decimeter antenna with your own hands? Do-it-yourself home TV antenna Which metal is best for making an antenna

The length of the tubes, and therefore the total length of the vibrator, depends on the frequency of the received television station. And it can range from about 50 to 230 MHz. This entire operating range is divided into 12 channels - they are marked on the program selector handle of the TV. So, for the first channel (the “longest wavelength” - about 50 MHz), the length of the vibrator (the distance between the remote ends of the tubes) should be 271-276 cm, for the second - 229-234 and then, respectively - 177-179, 162-163, 147-150, 85, 80, 77, 75, 71, 69, 66 cm. Therefore, before you start building the antenna, find out what channel it is on transmissions from a local television center or repeater.

So, the length of the tubes was determined. Their diameter can be 8-24 mm (most often, tubes with a diameter of 16 mm are used). Flatten one end of each tube and attach the tubes with metal clamps to the Holder and? insulating material (textolite or getinax with a thickness of at least 5 mm) so that the required distance is obtained between the remote ends, and the flattened ends are spaced 60-70 mm from each other. Attach mounting tabs to the flattened ends using screws - they will serve as a kind of tube outlets. It is better, of course, to weld the petals to the ends of the tubes to make the contact more reliable.

Install the holder with tubes. on a mast, which will later be installed on the roof. Now you need to connect a reduction from a coaxial cable RK-1, RK-3, RK-4 or another with a characteristic impedance of 75 Ohms to the antenna. But you cannot solder the cable conductors directly to the tube terminals. Install between the descent cable and the antenna matching device, which is a loop of two sections of the same coaxial cable. The length of the segments depends on the received television channel.

For the first channel, the size should be 286 cm, and 12 - 95 cm, for subsequent channels - 242 and 80, 187 and 62, 170 and 57, 166 and 52, 84 and 28, 80 and 27, 77 and 26, 74 and 25, 71 and 24, 68 and 23, 66 and 22 cm.

The connection of the matching device is shown in Figure 2. The central cores of the cable and sections are soldered directly to the terminals of the tubes and to each other, and the metal braids are connected with sections of copper wire without insulation. The soldering must be strong and reliable, and the soldering points must be protected with insulating tape.

The matching loop and lowering cable are attached to the mast. The length of the reduction cable must be sufficient to connect to the TV after installing the antenna on the roof. At the end of the cable, a connector is installed that connects to the TV socket.

The antenna is strengthened with guy ropes so that it stands firmly and the vibrator is located at a distance of at least 2 m from the roof.

To get the most powerful signal from the antenna, it needs to be oriented as accurately as possible to the television center (or to the repeater antenna). This work is best done by two or even three people. One slowly rotates the antenna around its axis, and the other, watching the TV screen, informs it about changes in contrast and image quality. The antenna is installed and secured in such a position that the contrast is greatest and there is no multi-contour in the image (the result of receiving a signal reflected from nearby buildings).

In summer cottages television signal can rarely be received without amplification: too far from the repeater, the terrain is usually uneven, and trees are in the way. For normal “picture” quality, antennas are needed. Anyone who knows at least a little how to handle a soldering iron can make an antenna for their dacha with their own hands. Aesthetics outside the city are not given the same great importance, the main thing is the quality of reception, simple design, low cost and reliability. You can experiment and do it yourself.

Simple TV antenna

If the repeater is located within 30 km from your dacha, you can make the simplest receiving part in design. These are two identical tubes connected to each other by a cable. The cable output is fed to the corresponding TV input.

The design of an antenna for a TV in the country: it’s very easy to do it yourself (to enlarge the size of the picture, click on it with the left mouse button)

What is needed to make this TV antenna?

First of all, you need to find out what frequency the nearest TV tower is broadcasting on. The length of the “whiskers” depends on the frequency. The broadcast band is in the range of 50-230 MHz. It is divided into 12 channels. Each requires its own length of tubes. Channel list terrestrial television, their frequencies and parameters of the television antenna for self-made will result in the table.

So, in order to make a TV antenna with your own hands, you need the following materials:

It would be nice to have a soldering iron, flux for soldering copper and solder on hand: it is advisable to solder all connections of the central conductors: the image quality will be better and the antenna will work longer. The soldering areas then need to be protected from oxidation: it is best to fill it with a layer of silicone, or you can use epoxy resin, etc. As a last resort, seal it with electrical tape, but this is very unreliable.

Even a child can make this homemade antenna for a TV, even at home. You need to cut the tube to the length that corresponds to the broadcast frequency of a nearby repeater, then saw it exactly in half.

Assembly order

The resulting tubes are flattened on one side. With these ends they are attached to a holder - a piece of getinax or textolite 4-6 mm thick (see picture). The tubes are placed at a distance of 6-7 cm from each other, their far ends should be at the distance indicated in the table. They are secured to the holder with clamps; they must hold firmly.

The installed vibrator is fixed to the mast. Now you need to connect the two “whiskers” through a matching device. This is a cable loop with a resistance of 75 Ohms (type RK-1, 3, 4). Its parameters are indicated in the far right column of the table, and how it is done is on the right side of the photo.

The middle cores of the cable are screwed (soldered) to the flattened ends of the tubes, and their braid is connected with a piece of the same conductor. Getting the wire is simple: cut a piece from the cable slightly larger than the required size and remove all the sheaths. Clean the ends and screw them to the cable conductors (it’s better to solder them).

Then the central conductors from two pieces of the matching loop and the cable that goes to the TV are connected. Their braid is also connected with copper wire.

Last step: the loop in the middle is attached to the rod, and the cable going down is screwed to it. The barbell is raised to the required height and “adjusted” there. To set up, you need two people: one turns the antenna, the second watches TV and evaluates the picture quality. Having determined where the signal is best received from, the home-made antenna is fixed in this position. To avoid having to struggle with “tuning” for a long time, take a look at where your neighbors’ receivers (over-the-air antennas) are pointing. The simplest antenna Made for the dacha with my own hands. Set and “catch” the direction by turning it along its axis.

Watch the video on how to cut a coaxial cable.

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Loop from a pipe

This do-it-yourself antenna for a summer residence is a little more difficult to manufacture: you need a pipe bender, but the reception radius is larger - up to 40 km. The starting materials are almost the same: metal tube, cable and rod.

The bend radius of the pipe is not important. It is necessary that the pipe has the required length, and the distance between the ends is 65-70 mm. Both “wings” should be the same length, and the ends should be symmetrical about the center.

Homemade antenna for a TV: a TV signal receiver with a reception radius of up to 40 km is made from a piece of pipe and cable (to increase the size of the picture, click on it with the left mouse button)

The length of the pipe and cable is indicated in the table. Find out what frequency the repeater closest to you is broadcasting on, select the appropriate line. Saw off a pipe of the required size (diameter is preferably 12-18 mm, the parameters of the matching loop are given for them).

Assembly

The tube of the required length is bent, making it absolutely symmetrical relative to the center. One edge is flattened and welded/sealed. Fill with sand and seal the other side. If there is no welding, you can plug the ends, just attach the plugs to good glue or silicone.

The resulting vibrator is mounted on a mast (rod). The central conductors of the matching loop and the cable that goes to the TV are screwed to the ends of the pipe, and then soldered. The next step is to connect a piece of copper wire without insulation to the braided cables. The assembly is completed - you can start “setting up”.

Beer can antenna

Even though it doesn't look serious, the image becomes much better. Tested many times. Try it!

Outdoor antenna made from beer cans

We collect it like this:

1. We drill a hole (5-6 mm in diameter) in the bottom of the jar strictly in the center.
2. We pull the cable through this hole and take it out through the hole in the cover.
3. We fix this can on the left on the holder so that the cable is directed to the middle.
4. We pull the cable out of the can by about 5-6 cm, remove the insulation by about 3 cm, and disassemble the braid.
5. We trim the braid, its length should be about 1.5 cm.
6. We distribute it over the surface of the can and solder it.
7. The central conductor sticking out 3 cm needs to be soldered to the bottom of the second can.
8. The distance between the two banks must be made as small as possible and fixed in some way. One option is duct tape or duct tape.
9. Everything, homemade UHF antenna ready.

Terminate the second end of the cable with a suitable plug and plug it into the required socket on the TV. This design, by the way, can be used to receive digital television. If your TV supports this signal format (DVB T2) or has a special set-top box for your old TV, you can receive a signal from the nearest repeater. You just need to find out where it is and point your television antenna there, made with your own hands from tin cans.

Simple homemade antennas can be made from tin cans (beer or beverage cans). Despite the frivolity of the “components,” it works very well and is very easy to manufacture

The same design can be adapted to receive VHF channels. Instead of 0.5 liter jars, use 1 liter jars. Will receive MV band.

Another option: if you don’t have a soldering iron, or you don’t know how to solder, you can do it easier. Tie two cans at a distance of several centimeters to the holder. Strip the end of the cable by 4-5 centimeters (carefully remove the insulation). You separate the braid, twist it into a bundle, and make a ring out of it, into which you insert a self-tapping screw. Make a second ring from the central conductor and thread a second screw through it. Now at the bottom of one can you clean out (with sandpaper) a spot to which you screw the screws.

In fact, for better contact, soldering is needed: it is better to tin and solder the braid ring, as well as the point of contact with the metal of the can. But it also works well with self-tapping screws, however, the contact periodically oxidizes and needs to be cleaned. When it starts snowing you will know why...

DIY digital TV antenna

The antenna design is frame. For this version of the receiving device you will need a cross made of wooden boards and a television cable. You will also need electrical tape and a few nails. All.

We have already said that for reception digital signal You only need a decimeter terrestrial antenna and a corresponding decoder. It can be built into televisions (new generation) or made as a separate device. If the TV has the function of receiving a signal in the DVB T2 code, connect the antenna output directly to the TV. If your TV does not have a decoder, you will need to purchase digital set-top box and connect the output from the antenna to it, and connect it to the TV.

How to decide on a channel and calculate the perimeter of the frames

Russia has adopted a program according to which towers are constantly being built. By the end of 2015, the entire territory should be covered by repeaters. On the official website http://xn--p1aadc.xn--p1ai/when/ find the tower closest to you. The broadcast frequency and channel number are indicated there. The perimeter of the antenna frame depends on the channel number.

For example, channel 37 broadcasts at a frequency of 602 MHz. The wavelength is calculated as follows: 300 / 602 = 50 cm. This will be the perimeter of the frame. Let's calculate the other channel in the same way. Let it be channel 22. Frequency 482 MHz, wavelength 300 / 482 = 62 cm.

Since this antenna consists of two frames, the length of the conductor should be equal to twice the wavelength, plus 5 cm for the connection:

• for channel 37 we take 105 cm of copper wire (50 cm * 2 + 5 cm = 105 cm);
• for channel 22 you need 129 cm (62 cm * 2 + 5 cm = 129 cm).

Assembly

It is best to use copper wire from the cable that will then go to the receiver. That is, you take the cable and remove the sheath and braid from it, freeing the central conductor of the required length. Be careful not to damage it.

• for channel 37: 50 cm / 4 = 12.5 cm;
• for channel 22: 62 cm / 4 = 15.5 cm.

The distance from one nail to another must correspond to these parameters. Laying copper wire begins on the right, from the middle, moving down and further to all points. Only in the place where the frames come close to each other, do not short-circuit the conductors. They should be at some distance (2-4 cm).

When the entire perimeter is laid, the braid from a cable several centimeters long is twisted into a bundle and soldered (wound if soldering is not possible) to the opposite edge of the frame. Next, the cable is laid as shown in the figure, wrapping it with electrical tape (more often, but the laying route cannot be changed). The cable then goes to the decoder (separate or built-in). The DIY antenna for your dacha for receiving digital television is ready.

How to make an antenna for digital television with your own hands - another design - is shown in the video.

K. Kallemaa (UR2BU), Tartu.

Over and over again, ultrashortwave operators ask their senior colleagues: “Which antenna should I choose?” It is impossible to answer this question accurately, since it all depends on the purpose for which the antenna is being built. If connections are assumed in all directions, for example within a city, then. Antennas with a circular diagram are very convenient, which often allow operation at distances between stations of 50-100 km. For long-distance communications, directional antennas are more suitable. In areas “densely populated” with ultrashort wavelengths or in cases where there is interference from some directions, it is undoubtedly better to use highly directional antennas.

These few examples are enough to understand that there is no antenna that is equally suitable for all cases. The radio amateur must choose an antenna that meets his basic requirements. Better yet, build two or three antennas and use them as needed.

It is unwise for a beginner ultrashortwave operator to choose any bulky and complex structure as his first antenna, during the construction of which he can make many mistakes due to inexperience. You should start with the construction of simple antennas and, as experience and knowledge grow, move on to more complex systems.

When choosing the type of antenna, you need to take into account what basic materials are available to the designer. If you cannot purchase pipes or rods for the antenna elements, then you can choose, for example, a “double square”, the construction of which only requires wire, wooden slats and a small amount of insulating material. It is also important how the supply line will be made - from coaxial or ribbon cable, or simply in the form of a two-wire line.

We must not lose sight of whether any measurements are needed when building the antenna. For a beginner, who also does not have measuring equipment, it is better to choose an antenna that will probably work well without tuning.

Let's look at a number of antenna types. Among them there are simple designs that can be repeated by every beginner, and complex ones, including antenna systems, which may be of interest to more experienced DX hunters. Since most of our ultra-shortwave radios operate in the 144 MHz range, antenna sizes are given specifically for this range.

The reader will note that no technical design details are provided for either antenna. But this should not interfere with construction, since operating techniques and many details are described in any amateur radio manual.

CIRCULAR RADIATION ANTENNAS

Cross-shaped dipole. The antenna consists of two half-wave vibrators 1, located at an angle of 90° to each other (Fig. 1). The radiation pattern of this antenna is far from a perfect circle, but in practice it produces quite good circular radiation. Since the characteristic impedance of one dipole is approximately 70 Ohms, when two dipoles are connected in parallel, the characteristic impedance is about 35 Ohms. We do not have such a coaxial cable at our disposal, so it is best to power the antenna through a quarter-wave transformer 3 made from a 50-ohm cable. A 75-ohm cable 4 runs from the transformer to the equipment. The balancing U-elbow 2 is made from the same cable.

Vertical antenna (Ground Plane). Emitter 1 (Fig. 2) and radial conductors 2 provide a circular diagram in a horizontal plane. The angle between the radial conductors and the emitter determines the characteristic impedance of the antenna.

At an angle of 90°, the wave impedance is approximately 30 Ohms, at an angle of 180° - 70 Ohms. Typically, an angle of 145° is chosen, which allows the antenna to be fed with a 50-ohm cable. The cable is connected to connector 3, mounted on a metal plate to which radial conductors are electrically connected. The emitter, to which the central conductor of the cable is connected, is installed on insulator 4.

DIRECTIONAL ANTENNAS

"Double Square" This popular directional HF antenna is also used on VHF (Fig. 3, a). Its gain (compared to a half-wave vibrator) reaches 5.7 dB, the forward/backward radiation ratio is 25 dB.

The distance between active vibrator 1 and reflector 2 is chosen to be 0.15 lambda, which allows the antenna to be powered with a 75-ohm coaxial cable 3. Experience has shown that the antenna fed in this way works quite satisfactorily. You can tune the antenna using a short-circuited cable connected to the gap in the reflector frame.

To balance the antenna, you can use a quarter-wave glass (Fig. 3, b), connecting it to the ends of the active vibrator 1. The glass consists of a metal cylinder 4 with two covers - metal 5 and dielectric 6. Cable 3 runs inside the glass, the cable braid is connected to the cover 5. The diameter of the glass should be 3-4 times larger than the diameter of the cable.

To make antenna elements, you can use a copper or aluminum tube, tape or wire yourself. various diameters. The “double square” takes up very little space and is structurally simple. This antenna has relatively good characteristics. The possibility of placing antennas of different ranges on the same cross-shaped rails is noteworthy.

Triangle Antenna (Delta Loop) belongs to the same family as the “square”, since the perimeter of the active vibrator is approximately equal to the wavelength. A special feature of this antenna is that all elements of its design are metal. The author of the antenna advised feeding it with a 50-ohm coaxial cable, but a 75-ohm cable is also successfully used for this purpose. The simplest triangular antenna is shown in Fig. 4. Active vibrator 1 is adjusted using a gamma matching device to which cable 3 is connected. Depending on availability measuring instruments adjustment is carried out according to the minimum SWR or maximum signal strength. To simplify things, reflector 2 can be made unadjustable.

UA1WW experimented a lot with the triangular antenna. He advises using 5- and 9-element options. The latter, due to its small horizontal radiation angle, is especially suitable for long-distance communications. A drawing of a 5-element antenna is shown in Fig. 5. Here 1 is an active vibrator, 2 is a reflector, 3-5 are directors. Since this is a completely new antenna for our ultrashort wavelengths, we present some design data.

A 4-sided duralumin pipe with a square side of 18-20 mm is most suitable for a load-bearing traverse; it is much more convenient to mount elements on it than on a round pipe (see Fig. 6).

The antenna elements are made of a copper or aluminum tube or rod with a diameter of 6 mm, the horizontal side is made of wire with a diameter of 3 mm. The dimensions of the elements (in accordance with Fig. 6) are as follows:

Triangular antenna- an object of interest for ultrashort wavelengths around the world. Taking into account the positive experience with it, we can assume that it will soon become one of the most popular antennas. Therefore, we draw the attention of those who want to experiment to one special type of it - a double triangular antenna (Fig. 7). The triangle dimensions of this antenna are slightly larger than those of a single antenna; the perimeter of the reflector is 2266, the active vibrator - 2116 and the director - 1993 mm. The distance between the reflector and the vibrator is 0.2 lambda, between the vibrator and the director is 0.15 lambda.

According to some data, the following gains were obtained for a double antenna (compared to a half-wave vibrator): one element (active vibrator) - 3-4 dB: two elements (vibrator and reflector) - 8-9 dB: three elements (reflector, vibrator in director), - 10-11 dB. This seems like a promising type of antenna and worth pursuing.

10-element antenna (Yagi). Undoubtedly, this is the most popular VHF antenna (Fig. 8). It gives a gain of 13 dB. The author carried out meteor communications with England and Belgium using such an antenna, and many long-distance communications due to tropospheric passage and “aurora”.

The passive elements of the antenna are made of bimetallic wire with a diameter of 4 mm, and the active loop vibrator is made of a 15 mm copper tube and the same wire. The characteristic impedance at the feed point is 300 ohms, so the 75 ohm cable is connected through a U-elbow, the length of which is 68 cm.

The length of the supporting beam is slightly more than 3.5 m, the diameter is 20 mm. The length of the reflector is 7-1060, the vibrator is 2-990, the directors are 3-10 - 933, 930, 927, 924, 921, 918, 915 and 912 mm, respectively.

Multi-band antenna. There are circumstances when it is not possible to install more than one antenna. But in addition to an antenna, a radio station often also needs a television antenna! Then the way out is a multi-band UKB antenna. One variant of such an antenna is shown in Fig. 9, a (top view) and 9, b (axonometric projection). It can be successfully used in the ranges from 50 to 220 MHz. The antenna gain at a frequency of 50 MHz is 7 dB, 144 MHz is 12 dB, and at 220 MHz is even 13.5 dB. This antenna is a two-story one. At a frequency of 50 MHz, two corner vibrators 1 operate on each floor, located at a distance of lambda/4. At a frequency of 144 MHz their length is approximately 3/4 lambda and therefore the result is a V-shaped antenna. At 220 MHz the vibrators are 5/4 lambda long.

The vibrators are connected to each other by 2 two-wire lines, and both floors by 3 lines, the length of which, depending on the range, is from 1/4 to 5/4 lambda. The distance between floors, if desired, can be changed within the limits allowed by the length of lines 3. The input impedance of the antenna at feed point 4 at frequencies of 50 and 144 MHz is about 300 Ohms, at a frequency of 220 MHz it drops to about 200 Ohms.

Antenna elements can be made from a tube or rod: vibrators - with a diameter of 10 mm; line 2 - with a diameter of 12 mm (10 mm is possible, then the distance between the centers of the line wires should be chosen equal to 64 mm): line 3 - with a diameter of 6 mm.

RADIO No. 8, 1973 p.20-23.

http://citradio.com/ukv/antennes/ant-873.html

When arranging a summer cottage, we try to make it as comfortable as possible for relaxation. This means that over time it acquires the amenities that we are so accustomed to in everyday life - water supply, heating and, of course, electricity. And where the latter exists, sooner or later television will definitely appear. But how, you ask, can you spend it at your dacha if purchasing an antenna, which, by the way, is not cheap at all, is not included in your personal budget? Yes, very simple! A few basics of radio electronics, a couple of pieces of iron and a minimal soldering kit and now, having thoroughly tired of the garden, you settle down on the country terrace to watch the evening news block.

Radio electronics and television broadcasting: 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 one single band - the decimeter band, and television transmitters cover almost the entire more or less populated territory. This makes it possible to “catch” a TV signal anywhere.

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

Based on this, among all the diversity television antennas The most accessible types for self-production will be the following:

1. All-wave (frequency independent)

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

1. Log-periodic range

Such an antenna can be compared to a fishing net, which sorts the prey during catching. This type antenna systems also has simple design, however, provides higher parameters than the all-wave.

1. Decimeter zigzag

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

Subtleties of making television antennas

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

If we are talking about a homemade antenna for a summer residence, you should not strive for ideal quality of contacts - even if they rust or burst, then at least not soon. But it is desirable that there be as few connections as possible in the antenna design, which will ensure stable and fairly clean reception.

The braid and core of coaxial cables are now made from inexpensive alloys that are corrosion resistant. Unlike classic copper, they are difficult to solder. Therefore, you need to be careful not to burn the cable.

To make an antenna and its cable connection, it is advisable to use:

Aluminum wire should not be used to make antenna elements - it will oxidize very quickly and lose its ability to conduct an electrical signal. Copper or cheaper brass is best suited for this.

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

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

As a result, the system will provide normal reception power. All you need to do is take the antenna to the roof of the country house and point it towards the nearest television tower.

DIY frequency independent antenna

The simplest all-wave unit is a pair of metal plates mounted on a wooden slats 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 panels should be 90 degrees. It is not necessary to solder the wire to the zero potential point of the all-wave oven - it is enough to ensure that it is securely fastened.

A 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 efficiency factor - an indicator of the ratio of the signal power received at 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 radio is not suitable for receiving a television signal in an area with strong interference or where the on-air 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 slats;
• copper wire.

The cans are secured to the rail (mast) using electrical tape at a distance of about 7 cm from each other.

Self-tapping screws are screwed into them, and the stripped ends are screwed to the protruding ends. antenna cable. The latter is fixed to 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 unit by adding a few more sections from tin containers. Afterwards, all that remains is to securely secure 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.

Manufacturing a log-periodic television antenna

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

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

1. The calculation of the length of the dipoles begins with the second longest one.
2. Taking the reciprocal of the progression index, the length of the longest dipole is calculated.
3. Next, it remains to calculate the shortest - the first - dipole, and then, based on the selected frequency range, the length of the “zero” dipole is accepted.

To achieve maximum reception power, there must be a distance between the dipoles of 0.03-0.05 wavelengths, but not less than double 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 should be no more than 3-4 dipole diameters.

For normal operation of the LP antenna, 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 decimeter waves, as a result of which the television tuner will be unable to sense the signal.

The cable to the receiving line cannot be secured from the outside, as this will sharply reduce 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.

You can improve the design of an LP antenna by installing linear or fan-shaped hangers of a meter field on it. This system is called “delta”.

Delta antenna circuit

Zigzag antenna for a summer residence

The Z-antenna system with a reflector provides almost the same TV signal reception parameters as the LP antenna. However, its main petal is horizontally twice as long. This makes it possible to catch a signal from different directions, which is especially important 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 about 6 mm thick. If you choose the latter, you won’t be able to solder it with regular solder or flux - 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 fastening the canvas;
• cross slats;
• dielectric plates and gaskets;
• mounting plate;
• feeder line;
• power plate.

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

The sides of the Z-antenna are made of solid metal or in the form of a mesh covered with a sheet of tin. When laying coaxial cable along the body of the antenna, 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 braid is carefully soldered to the fabric.

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

Options for making television antennas yourself in the photo

There are other types of antennas suitable for self-production - wave, “Polish”, simple frame and even primitive satellite. But no matter which option you choose, proper calculation of the parameters is required. The technique can be found in the technical literature on radio electronics. However, it is much easier and simpler to ask advice from those who already have experience in making this kind of antennas.

Making your own antenna for a summer house on video

Symmetrical vibrator. A symmetrical vibrator can be thought of as a long line, open at the end, with the wires rotated 180 degrees. The simplest and most commonly used antenna is a half-wave vibrator. A symmetrical half-wave vibrator is shown in Fig. 11. 9. A symmetrical half-wave vibrator requires a symmetrical power supply. An asymmetrical feeder line in the form of a coaxial cable can be connected to it, but only through a balancing device, which will be discussed in paragraph 11. 7.

The half-wave vibrator is powered at the current antinode (geometric center) and the input resistance is equal to the radiation resistance. Theoretically, the input impedance of a half-wave vibrator is 73 ohms, but this value is determined on the assumption that the antenna conductor is infinitely thin and the antenna is located infinitely high above the ground. In Fig. 11.10, a. The directional diagram of a half-wave vibrator in the horizontal plane is given. She represents the number eight.

There are two radiation maxima perpendicular to the antenna, and two minima along the vibrator axis at 90 and 270 degrees. There will be no reception or radiation from these sides during transmission. The literature usually provides attenuation values ​​in these directions, which reach 38-40 dB, which is an attenuation of 80-100 times. The radiation angle in the vertical plane depends on the height of the antenna above the ground. At an antenna height of L/4 (Fig. 11.10,6.), the radiation will be vertically upward, and at a height of L/2 (Fig. 11.10, c.), the radiation will be at an angle of 30 degrees to the horizon. This antenna mounting height is the best. Increasing the antenna height to 1 L,

Often radio amateurs are faced with the question of how the metal and reinforced concrete roofs on which they are mostly installed affect

antennas, onto the radiation pattern in the vertical plane. They influence, but they cannot be considered as an ideal earth.

In order to be able to put an equal sign between the roof and the ideal ground, this surface must have at least an area equal to L^2 .

In the HF and VHF ranges, the diameter of the half-wave vibrator wire is rarely less than 2 mm, while the input impedance of the antenna is in the range from 60 to 65 Ohms. From the graph (Fig. 11.11) you can determine the input resistance RBX of a half-wave vibrator depending on the L/d ratio.

Both quantities are taken in the same units, meters or centimeters.

When determining the geometric dimensions of a half-wave vibrator, let us consider the difference between the “electrical” and “geometric” lengths of the vibrator.

In fact, the electrical and geometric lengths of the vibrator are equal only when the antenna conductor becomes infinitely thin. Using the graph, the shortening coefficient of the vibrator is determined depending on the L/d ratio.

The antenna can be made not only of thin wire with a diameter of 2 - 4 mm, but also of copper or duralumin pipes of various diameters. With a smaller antenna conductor diameter, it has a narrower bandwidth, and with a larger diameter, its bandwidth increases. This must be taken into account when the overlap range is large. For example, for the range 28.0 - 29.7 MHz or in the VHF sections 144 - 146 MHz and 430 - 440 MHz.

Example. It is necessary to find the geometric length of a half-wave vibrator for a frequency of 145 MHz for a tube with a diameter of 20 mm from which the antenna will be made. For a frequency of 145 MHz, L = 206 cm. We obtain the ratio L/d206: 2.0 = 103 From the graph we find K = 0.91 (indicated by a dotted line on the graph). Then the required length of the half-wave vibrator is: L/2 x K = 103 x 0.91 = 93.7 cm. Antennas for the bands 160, 80, 40 and 30 meters, which are longer, can be made from bimetal, which is widely used in wired broadcasting. The steel core of such a wire is coated with a thick layer of copper and the wire has greater strength. This wire has a diameter of 3-4 mm. Table 11.1 shows the dimensions of half-wave vibrators.

In half-wave antennas with power in the middle (Fig. 11.9), antinodes U and current minima I are formed at the ends of the vibrator. This indicates that there is a high resistance at the ends of the half-wave vibrator. When feeding a half-wave vibrator from the end, you must choose a different power supply circuit. The antenna is turned on through a matching device. As a matching device, you should choose a U-shaped circuit, the input impedance of which can be equal to the characteristic impedance of the coaxial cable, i.e. 60 - 75 Ohm. In Fig. 11.13 shows such an antenna connection diagram.

In modern urban planning, high-rise buildings are mostly built. This can be used in the construction of an amateur radio antenna system.

To install an antenna on the roof of a house, you must obtain permission from the relevant services.

Antenna for 160 meters range. In Fig. Figure 11.12 shows two half-wave vibrator antennas located at an angle of 90 degrees.

By switching these antennas, you can cover all directions. Antennas A and B have the same length. Their length according to table 11.1 is 75.79 meters. To match the high-resistance input of a half-wave vibrator, fed from the end, with a feeder made of coaxial cable with a characteristic impedance of 60 - 75 Ohms, it is necessary to build a matching device in the form of a U-shaped circuit tuned to the average frequency of this range. The U-shaped circuit is placed in a metal waterproof box on which are installed: a high-frequency coaxial connector for connecting the coaxial cable of the feeder, two or three high-frequency bushings designed for high HF voltage, and a terminal for connecting a “counterweight” made in the form of a rectangle around the perimeter roof - G. Its length is not critical. Feeder D can be placed in the ventilation duct leading to your apartment. In Fig. Figure 11.13 shows a diagram of a matching device. The metal box contains: RF choke, relay P1, P2, capacitors C1, C2, coil L and diodes D1, D2. Relay direct current low-voltage, any type, but its switching contacts must be high-frequency, designed for switching. Such relays were used in RSB-5 or other types of radio stations. The relay is powered via a coaxial cable. When a positive voltage is applied, relay P1 is turned on, and relay P2 turns on when a negative voltage is applied. Relay P2 can be used to connect another antenna, and its input impedance should be low-impedance. For example, a half-wave vibrator with power in the middle or a quarter-wave vertical antenna. Capacitor C1 for the range of 160 m - 1700 pF, designed for the corresponding reactive power. Capacitor C2 - variable capacitance - up to 300-350 pF.

It must have a large gap between the plates, since there will be a large RF voltage between them. The capacitor axis is placed outside the box for easy adjustment of the matching device. Inductor L - 20 µH. The RF chokes are wound on ceramic frames with a diameter of 20 mm, with PELSHO wire 0.3 - 0.35 mm. Winding length 120 mm turn to turn. From the side connected to the HF line

at a length of 10-12 mm, the inductor turns are sparse to reduce the interturn capacitance. Coil L contains 30 turns of PEV 2.0 wire, wound on a 100 mm frame made of high-frequency material.

The matching device is configured as follows. A power of 8-10 W is supplied to the input of the device from the transmitter. By adjusting capacitor C2, resonance is achieved. Control can be carried out using a field indicator or by the glow of a neon lamp. It should be noted that the tuning can be for harmonics, i.e. on the 80 meter band. It is best to control the tuning using a heterodyne resonance meter (GMR), then the error is reduced to a minimum.

A similar antenna can be made for other bands, and not only half-wave. It may be a harmonic antenna. In this case, its length should be equal to a certain number of half-waves, which is calculated by the formula:

From the above example it can be seen that the 160-meter band antenna can also be used as a harmonic antenna for other bands if you install an additional U-shaped circuit tuned to the selected band. Antennas for bands 80 and 40 meters.

It can be single-band or dual-band. In the dual-band version, it has two advantages. Only one mast is required and, unlike the radiation diagram of a half-wave vibrator located horizontally, it also has radiation along the axis of the antenna with vertical polarization, since it is inclined towards the earth.

Each of the antennas is a symmetrical half-wave vibrator and when powered by an asymmetrical coaxial cable, a balun is required. In its absence, the radiation pattern is distorted, the SWR becomes large, which indicates large losses in the feeder and, in addition, the outer braid of the cable begins to radiate and create TV interference. Both antennas can be connected in parallel, but the best option is separate power supply via a relay, as in the description of the antenna for the 160-meter range. Parts A and B of the 80-meter range antenna are 18.72 m each, and B and D are 9.65 m each. Balancing element D is located closer to

the place where the feeder is connected to the antennas; switching relays can also be located there. The mast has a height of 16 m, and the distance between the attachment points of the guys of the 80-meter dipole is shown in the figure. It is desirable that the ends of the dipole be at a height of at least 1.5 m above the surface.

The balancing element is shown in Fig. 11.27, at. For these bands and higher frequencies, a multi-band antenna created by radio amateur W3DZZ can be recommended. This antenna is a resonant, symmetrical vibrator for 80 and 40 m. Due to the fact that the amateur bands are multiples of one another, this antenna is also excited at harmonics, i.e. on 20, 15 and 10 m bands. It is simple, not very long and provides operation on all amateur bands, starting from 80 m. Its appearance is shown in Fig. 11.15. The inductance of the coils L1 and L2 is 8.3 μH, and the capacitance of the capacitors is 60 pF. Circuits L1 C1 and L2 C2 are filter plugs tuned to a frequency of 7050 kHz. Coils L1 and L2 have a diameter of 50 mm, are wound with PEV-2 wire with a diameter of 2 mm, and contain 19 turns over a length of 80 mm. The measurement of the resonant frequency of these circuits can be controlled using a GIR. capacitors should be 3....5 kilovolts. The role of the plug filter is that at the resonance frequency the reactance of the circuit is several kilo-ohms. The circuit connected to the antenna wire break when operating on the 40-meter band is excited and creates a very high resistance, which, as it were, turns off part of the antenna. As a result, the working sections remain two halves of the vibrator of 10.07 m each, which is equal to L/2 of this range.

In Fig. 11.15 a. The design of a circuit with a homemade high-voltage capacitor is given. It consists of a duralumin tube with a diameter of 30 mm and a length of 120 mm, which is the first plate of the capacitor, and a rod 4 with a diameter of 8 mm, having an M8 mm thread at the ends. Insulating sleeves 3 are made of polystyrene or fluoroplastic. On one side, a ring 5 made of duralumin is put on the tube, to which one end of the coil L is attached. The second end of the same coil is attached to the flange 2 connected to the rod 4. The rod 4 tightens the bushings 3 and is the second plate of the capacitor. - the gap between flange 2 and the end of the tube should be large 8-9 mm, because there will be a large high-frequency voltage between them. Bracket 1 increases the distance between antenna conductor A and the end of rod B to avoid breakdown. Balancing element B is discussed in paragraph 11.7.

After completing the manufacture of the circuit, it is necessary to tune it to a frequency of 7050 kHz. This is done by stretching or compressing the coil L. The resonant frequencies of the W3DZZ antenna are 3.7; 7.05;

14.1; 21.2 and 28.4 MHz. A coaxial cable is used to power the antenna.

Rice. 11. 16 ABC antenna and radiation diagrams. with a characteristic impedance of 75 Ohms of the appropriate type, taking into account the transmitter power.

It is one of the low-noise directional radiation antennas. ABC antenna is good to use in rural areas, where there is a large area for its placement. The antenna has a length of 300 m. With a slight deterioration in parameters on the 160th range, it can be shortened to 200 m, and on the 80-meter range to 100 - 120 m. At the end, it is loaded onto a 600 Ohm resistor of the appropriate power. The height of the suspension is 3 - 4 m. The counterweight-grounding is buried to a small depth under the antenna. It can operate on all amateur bands. Antenna input impedance 600 Ohm. It is connected to the transmitter directly, and when using a coaxial cable - through a matching device, such as when feeding a 60-meter antenna (Fig. 11.13). Table 11.2 gives the values ​​of Cl C2 and inductance L for the 160 and 80 meter bands, where it is advantageous to have directional radiation for communication with DX correspondents.

When working with this antenna, you must be careful because...

The antenna wire is under high frequency voltage. Diagram fig. 11.16.6. shows the radiation angle in horizontal, and Fig.

11.16, at. in a vertical plane.

in phase. As a result, we obtain a radiation pattern in the horizontal plane that is more elongated (Fig. 11.17c) than that of a single vibrator. Thus, the gain of two common-mode antennas is greater. The radiation pattern of these common-mode antennas in the vertical plane will have a smaller radiation angle (shaded lobes in Fig. 11.17d) than with a single vibrator, whose radiation angle is 30 degrees. Let's transform these two antennas into a square by connecting the ends of the half-wave vibrators, as in Fig. 11.17.6. The parameters of this new antenna are the same as a two-story in-phase antenna. It is characterized by high gain at a small radiation angle to the horizon, which will provide DX communications. In Fig. 11.17, d. shows modifications of the loop antenna. It differs only in geometric shapes and location in space. The input impedance of loop antennas is 110-120 Ohms. Separately, it should be said about the loop antenna shown in Fig. 11.17 a.m. This antenna has all the parameters that were mentioned, but differs in that it is not located vertically, but at an angle of 45 degrees to the surface. This type of loop antenna arrangement can be recommended for the 160, 80 and 40 meter bands. -and due to the tilt, one of the lobes of the diagram is pressed more towards the horizon, and in the direction in which the antenna is tilted, DX communications can be carried out. When calculating loop antennas, their perimeter is equal to: l=Lx1.02 Example. Calculate the perimeter of the loop antenna for F = 3.65 MHz. L = 300000: 3650 kHz = 82.19 m. l = 82.19 m. x 1.02 = 83.83 m.

An English amateur radio G3AQS loop antenna was published in the amateur radio literature for the 80-meter range, at a frequency of 3.8 MHz. In Fig. Figure 11.18 shows such an antenna, converted to a frequency of 3.65 MHz. Its dimensions are given in the figure. The balun broadband transformer has the following data.

On a 60 mm frame made of high-frequency material, a coil is wound turn to turn into two wires with a diameter of 1.8 mm with resin insulation.

The number of turns is 7. In a balun transformer, terminals 1 and 3 are the beginning of the winding, 2 and 4 are the ends. Static multi-element antenna.

Such an antenna can be installed if the location of the buildings is convenient for this. In Fig. 11.19 shown seven-element wire antenna "wave channel". A loop vibrator can be selected as the active element. Its dimensions for the 40-meter range: A - 21.91 m; B - 19.91m; 18.38m; E, F - 17.91 m each. Distance between elements: AB - 8.51 m, and between the rest - 5.1 m. Balancing element - C is shown in Fig. 11.27 c. The active vibrator can be of a different design, for example, as in Fig. 11.13.

Then the matching device will have the following parameters:

capacitor C1 - 250 pF, coil inductance L - 5.2 μH, capacitor C2 - up to 120-150 pF. Counterweight - grounding goes down along the wall of the building. A metal pipe or sheet of metal is laid in the ground, to which the grounding counterweight is connected. Such an antenna has a gain of 11-12 dB, which will significantly increase the possibilities of communications with DX correspondents. High frequency range antennas.

To obtain directed radiation in the technique of short and ultrashort radio waves, systems of passive elements are used, located in a certain way relative to each other. The currents flow in them either in phase or in antiphase. If wires carrying antiphase currents are separated by a distance commensurate with the wavelength, the system will become radiating. Unidirectional radiation is obtained when in emitters located at a distance of a quarter wave from each other, the currents are shifted in phase relative to each other by a quarter of a period.

A passive vibrator can play the role of a mirror (reflector), or vice versa, direct the radiation towards itself. In this case, the passive element is called the director. A wave emitted by the antenna and incident on the reflector induces significant currents in it. If the induced current is 90 degrees ahead of the current in the antenna in phase, then the reflector will perform its functions without requiring independent power supply. The desired phase shift can always be set by appropriately adjusting the reflector, which consists in selecting its length. In this case, the reflector can represent active, capacitive or inductive resistance for induced currents, as a result of which the currents in it will be phase shifted by one or another angle with respect to the exciting wave. However, due to the fact that the current induced in the reflector is always less than the current in the antenna, complete compensation of backward radiation cannot be achieved. Therefore, the radiation pattern of an antenna with such a reflector will always be somewhat worse than that of an antenna with a powered reflector.

Single-band multi-element antenna. The simplest 3-element “wave channel” antenna is shown in Fig. 11.20. Its gain is 8 dB, and the input impedance is 75 Ohms. In order to have such an input impedance, convenient for matching with a coaxial cable of the same wave impedance, it was necessary to use a loop vibrator. For some ranges, dimensions are given in Table 11.3. Tri-band This antenna was proposed by a Lithuanian radio amateur, former UP2NK. It operates on the 20, 15 and 10 meter bands. This antenna is slightly smaller than a full-size one. The general view of the antenna is shown in Fig. 11.21:1,2,3 - elements of the 15 and 20 meter bands; 4,5,6 - elements of the 10-meter range; 7 - antenna traverse; 8 - vertical racks; A - y (gamma) matching elements; B, C - guys; 9 - nut insulators; 10- two-wire lines; 11- capacitors at the elements; 12 - insulators; L - contour. The antenna on each band has 3 elements. Elements 1, 2 and 3 (Fig. 11.21, a.) represent a director, vibrator and reflector for ranges of 20 and 15 meters. The director of the 10-meter range 4, the active vibrator 5 and the reflector 6 are placed separately on the traverse. Each antenna is powered by a separate wave cable

Table.11.3 Dimensions of wave channel antennas

resistance 50-75 Ohm. A relay switch is installed at the base of the mast, allowing one of the antennas to be connected to a common feeder going to the radio station. The design of active elements of the 20 and 15 meter ranges is shown in Fig. 11.22, a. On the traverse in the center of elements 1,2 from Fig. 11.21 a. vertical racks 8 with a height of 950 mm are installed. They are intended for fastening guy wires B, B, which are made of bimetal or copper wire with a diameter of 4-5 mm. These guys are part of the 20 meter band elements. Guys are attached to the director and reflector posts through nut insulators 9. Guys B and C on the director and reflector near the insulators form a two-wire line 300 mm long with a distance between the wires of 50 mm. At the end of the line there is a jumper 10, with the help of which the director and reflector of the 20-meter range are configured. On the active element in the upper part of the rack there is a platform made of insulating material, on which a coil L is installed, having 7 turns with a diameter of 35 mm, wound with PEV-2 wire with a diameter of 3 mm. The middle turn of this coil is grounded.

and extension coil L. The active element of the 15-meter range is made of a duralumin tube with a diameter of 20 mm. At the ends of the vibrator, insulators 12 made of textolite are reinforced. Their sizes are shown in Fig. 11.22, a. The antenna of this range is connected to the feeder via at matching element, the dimensions of which are shown in Fig. 11.22. at The variable capacitor, which is used to match the feeder with the antenna, must be placed in a moisture-proof box. Table in Fig. 11.22, g. shows the dimensions of the director and reflector of the 15-meter band. The dimensions of the 10-meter band elements are shown in Fig. 11.22, at. The antenna of this range is also connected to the feeder via

matching element A. It is made of a tube with a diameter of 12 mm.

The antenna traverse is made of duralumin pipe with a diameter of 50...70 mm. The installation dimensions of the elements on the traverse are shown in Fig. 11.21.6.

Elements of the 10-meter range are designated D - director, B - active vibrator, R - reflector. According to the author, the antenna gain at 20 m is 7 dB, at 15 m -7.5 dB, at 10 m - 9 dB. Front to back ratio at 20 m - 17 dB, at 15 m - 19 dB, at 10 m - 23 dB. SWR on all bands is no worse than 1.2. The width of the diagram in the horizontal plane is 50-70 degrees.

connected to each other through textolite insulators 4, inside of which steel rods 16 with a diameter of 10 mm are inserted, creating the strength of these insulators. The ends of the horizontal pipes in the middle of the cross are attached to flanges 6 through insulating inserts 5 made of textolite. Flanges 6 are made of solid duralumin 10-12 mm thick and have dimensions of 300x300 mm; cylindrical bougies are installed in the center, with which the flange is attached to the traverse. Separation of horizontal structural elements into parts is necessary so that in the field of horizontal polarization there are no structural elements whose electrical lengths are close to L/2 and L/4 of the selected ranges, because finding such

Table 11.4 Dimensions of the "Double Square" tri-band antenna

magnitudes in the field of emitters will worsen the radiation pattern, gain and forward-backward radiation ratio. In Fig. 11.23 shows some design data of this antenna, and the dimensions of the frames and installation data for the placement of insulators are indicated in Table 11.4.

The dimensions given in the table are identical for all sides, because A-A"=A"-E, OV"=OB, etc. The diameter of the traverse pipe is 70 mm. The distance between the frames is 2.54 meters, i.e. on the 20-meter band 0.12L, on the 15-meter band 0 ,18L, on 10 meter 0.24L. The antenna frames are made of bimetal with a diameter of 3 mm. Porcelain support insulators are used on electrical power panels. Homemade end insulators are made of plexiglass with a thickness of 10-12 mm. M8 bolts are installed on these insulating platforms. . on the roof of a multi-storey building. Brass sliding bearings 7 are attached to the mast. The antenna traverse is attached to the rotating part of the mast 18. The gearbox 8 is located at the base of the mast and transmits rotation through the swivel joint 9. A synchronous sensor and a rotation limiter of the antenna are installed near the gearbox. only one rotation of the antenna. The gear shaft had a speed of 2 revolutions per minute. Each active frame has its own 75-ohm coaxial feeder. The reflector tuning elements (L1, L2, L-) are a two-wire line made of a copper passage with a diameter of 2 mm. On the VHF bands, the power of the transmitters is low and in order for the communication to be reliable, it is necessary to direct the radiated power to the desired correspondent. This problem can be solved by directional antennas with high gain. Let's consider several antennas of this type. In Fig. 11.24, a. shows a 6-element “wave channel” antenna for the 145 MHz range. The active vibrator and reflector are made in the form double square. This antenna matches well with a 75 ohm feeder without a balun. The cable screen is connected to point A, and the central core to point B. The gain of this antenna is 12 dB, and the input impedance is 75 Ohms. The forward-backward ratio is more than 30 dB.

In Fig. 11.24, d, e. Some dimensions of a 14-element “wave channel” antenna for a frequency of 435 MHz are given. The dimensions of the elements and the distances between them are given in Table 11.5.

It differs from the previous one in that a loop half-wave vibrator is used as an active element. In Fig. 11.24, g. the inclusion of a balancing element is shown. Antenna gain 16 dB. Input impedance 75 Ohm. The balancing device is a quarter-wave cylinder with a diameter of 30-40 mm. It is better to make it from brass or copper, but in extreme cases, you can use a thin-walled duralumin tube. Special attention