Antenna six squares calculation. Loop antenna for receiving Russian multiplexes

Television today is in every home. With the development of technology, the quality of television signals and methods of their transmission are changing. And if only yesterday antediluvian analogue broadcasting was used, today exclusively digital broadcasting is persistently discussed.
In Russia, television and radio broadcasting is carried out by the state company RTRS. Since 2012, a government decree has recognized a unified digital standard terrestrial television DVB-T2, multiplex digital broadcasting standard. The RTRS company, as the only broadcast operator, offers two multiplex packages (RTRS-1 and RTRS-2) for free viewing. All you need is a modern receiver-antenna, one of the options of which today we propose to make with your own hands.

This homemade product is based on the development of engineer Kharchenko K.P., who proposed similar antennas for deci meter range(DCV), popular in the 90s of the last century. This is similar to aperture antennas, based on a zigzag-shaped feed. The signal is accumulated by a flat reflector, which is at least 20% larger in size than the vibrator.
The television signal is transmitted by waves with horizontal polarization. In a simplified form, such an antenna consists of two horizontal loop vibrators connected to each other in parallel, but disconnected at the feeder (cable) connection point. Overall dimensions are given on the basis of Kharchenko’s article “Antenna of the DCV range”, and are calculated according to the proposed formulas. According to this technology, such antennas can be designed even for a weak signal of about 500 MHz.

What is needed to assemble the antenna

Materials:

• Barbecue grill;
• Aerosol paint for cars;
• Solvent or acetone;
• A set of drills for a conventional drill;
• Coaxial television cable – no more than 10 m;
• Half a meter of HV PVC pipe, diameter – 20 mm;
• Metal dowels for drywall;
• Copper wire for the antenna vibrator, core diameter – 2-3.5 mm;
• Two thin metal plates.

Tools:

• Soldering iron powerful 100 W;
• Screwdriver with attachments;
• Hot glue gun;
• Pliers, hammer, wire cutters;
• Painting knife, tape measure, pencil.

Let's start making the antenna

Making a vibrator frame

We measure the required length of copper wire with a margin of about 1 cm. You can also use a copper or aluminum tube with a diameter of up to 12 mm.

We clean the copper core from the insulation and level it with a hammer on a hard surface. Mark the middle and make a 90° bend. The most accurate way to do this is in a vice, lightly pressing the copper core and leveling it with a hammer.

According to our calculations, the sides of the squares will be 125 mm. We mark them with a tape measure and make bends.

Using side cutters, we bite off a small fragment from one end, making the tip pointed at 45°. After bending the second square, we carry out the same procedure, biting off the final end of the core. The squares can be slightly bent for this purpose.

On the middle bends of the squares we achieve a distance of 10-12 mm. At the ends we make shallow cuts with a needle file. This will help us pull both free ends together and secure them with thin copper wire.

Using liquid rosin or flux, we tin the middle bends with a soldering iron. This must be done on all sides of the copper core of the vibrator.

We strip the coaxial cable by 4-5 cm. We twist the braid or outer conductor into a single wire and wrap it around one of the bends. We solder it to the copper core with a soldering iron.

We strip the insulation of the inner conductor and also wrap it around the next bend of the frame. You need to solder it carefully, holding the insulation with pliers, since the temperature can simply move it away from the center. We first heat the frame in the soldering zone, and only then the conductor itself.

We fix the coaxial cable connection with a nylon tie, degrease it with a solvent and isolate the soldering points with hot glue using a gun. You can correct defects in the resulting cast form of glue with a hairdryer.

Preparing the reflector

We use an inexpensive barbecue net as a reflector or reflective screen. This is a good material, since even steel samples of such products are covered with a corrosion-resistant anodized coating, not to mention stainless steel. A heat exchanger from a modern refrigerator or a dish drying rack would also be suitable. The main thing is that this element, if possible, does not rust in the air.
The reflector grid must be larger than the vibrator frame, but does not have to be symmetrical. We cut off the handles from the grille; they will be superfluous in our design.

We place the antenna frame in the middle of the reflector and mark its mounting locations. For fastening, you can use two plates of any metal. We bend them along the grid and drill holes with a diameter of 5 mm.

Assembling the antenna

We cut two pieces of PVC pipe 75 mm long, and screw a self-tapping screw into the end of each, cutting off the protruding parts. We break off the pointed ends of the plasterboard dowels and screw them into the opposite end of the tubes.

We screw both PVC stands to the strips on the reflector with self-tapping screws. We tin the frame at the ends suitable for the racks for better heat transfer.

On the racks we mark the height of 68 mm, and put it at risk. We heat the ends of the frame with a soldering iron and solder them into the racks to the required marks.

EXTERNAL UHF ANTENNA WITH INCREASED EFFICIENCY

The quality of television signal reception depends on many reasons. In urban conditions, interaction between the main wave of the TV signal and reflected waves is inevitable. With direct visibility between the receiving antenna and the transmitting antenna, the main wave and waves reflected from the ground, squares, streets, and roofs of buildings arrive at the receiving point.

For radio waves, a large modern city is, figuratively speaking, a pile of “mirrors” and “screens,” which are bridges, factory chimneys, and high-voltage lines. High-rise buildings, like a passive repeater, re-radiate waves from the transmitting antenna. The nature of radio wave propagation is very complex, even close to 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 shadow of trees occurs in the summer. Adding and subtracting the main and reflected radio waves results in the strengthening of some television signals and the weakening of others.

Loop antennas in these conditions give good results due to the weakening of reception in the lateral and reverse directions; they are less susceptible to the influence of electrical interference and, in particular, interference from the ignition of internal combustion engines.
For long-distance 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 television channel ....38
Range accepted television channels…30 – 57
Polarization of received signals………horizontal

From a wide variety of loop antennas for the range DMV often make an antenna "triple square". What to do if the triple square gain 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 I use an antenna amplifier 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 to combine four triple squares into an antenna system - a phased array. The antenna gain is much greater than a single triple square, and the dimensions are quite acceptable. The dimensions of the design of one of the four triple squares are shown in the figure.

To make a triple square, you will need galvanized steel wire with a diameter of 3 mm. Galvanized wire is a wire that has a tin coating. Such wire is easier to coat with solder and does not rust in the open air. To make one triple square, 2 meters of wire are required. The wire piece should not have sharp bends, dents, scratches, rust or other defects. Before making the antenna, the wire blank is thoroughly wiped using a solvent. The wire is bent according to the pattern showing the triple square construction. The wire joints at the top of the squares are soldered. Sections of the wire at the joints are coated with flux prepared from hydrochloric acid by etching with zinc. Using a soldering iron with a power of forty watts, or better yet sixty watts, areas are covered with low-melting solder, as much 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 millimeter and soldered again. Finally, the joints are well soldered over the burner of a gas stove, using solder and rosin. The remaining rosin is removed from the resulting structure and washed off with a solvent. The junction must be well covered with tin, ensuring reliable contact and mechanical strength. Triple squares cannot be painted or varnished.

Before combining triple squares into a phased array, each one must be tested and adjusted. Testing 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 indoors can be black and white with a lot of noise.

The triple square setting is performed based on the least amount of noise on the TV screen. If one triple square does not produce a color image, it doesn’t matter; when combined into a phased array, the image quality will improve significantly. Having connected the triple square to the antenna input of the TV, you need to find the point of soldering the cable to the lower vertical part of the antenna structure, moving the connection point vertically. When moving the connection, the cable center core and cable shield must be connected at the same level. In some instances of the triple square, the 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 instances as shown in the figure, in the third instances in the middle. Each triple square has its own optimal cable connection point. After completing the setup and checking the triple squares, it is important not to mix up the cable connection points.

To obtain good quality antenna performance, you should make 6-8 triple squares, from which select four that give the best results.

The triple squares, which are phased array elements, are connected by a coaxial cable. The basis of the antenna design is a wooden frame. The length of the vertical cable sections connecting two triple squares is selected experimentally. It is impossible to accurately determine the length of cable sections in advance due to differences in the parameters of different types of cable and the unpredictable properties of manufactured triple squares.

Two triple squares are secured by wrapping a polyvinyl chloride tube on one vertical frame element, which is a wooden block. Alternately, identical sections of cable with a length of 220, 240, 260,280, 300 millimeters each are connected to the triple squares. The opposite ends of the cable sections are connected screen-to-screen and core-to-core and connected to the cable going to the antenna input of the TV. Based on the best image quality, the length of the vertical cable sections connecting the two triple squares is selected. The main contribution to the adjustment is the length of the cable sections compared to the distance between the triple squares. When setting up, you can shorten or increase the distance between the triple squares, but this will not give much effect, so the distances between the triple squares are not shown in the design figure. The image on the TV screen should be better than with a single triple square reception.

The frame is temporarily assembled from four wooden blocks fastened together with rope. Four triple squares are installed on the frame, connected by vertical cable sections. The length of two identical horizontal sections of cable connecting the vertical sections with the cable laid to the antenna input of the TV is determined experimentally. For final settings two identical horizontal segments 130, 150, 170 or 190 millimeters long are soldered alternately.

For the final production of the frame, you will need four wooden blocks 8-11 millimeters thick, 60-70 millimeters wide, 520 millimeters long, and three wooden blocks of the same thickness and width 490 millimeters long. The ends of the bars are coated with epoxy resin and dried for five days, then the entire surface of the bars is covered with epoxy resin and dried for five days. After coating with epoxy resin, the wooden blocks are painted with nitro paint at least twice. Before installing the triple squares and cable sections that combine the 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 has dried, the two screws connecting the upper horizontal bar with the vertical bars are unscrewed. The four screws securing the central horizontal bar remain.

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

For correct phasing of the antenna system, the central conductors and screens of the coaxial cable sections are connected to triple squares in accordance with the phasing diagram. 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 weather influences. The PVC tube and cable are secured with a thread to a horizontal bar. The soldering of the screen and the central core of the cable sections is insulated from each other using electrical tape. Two vertical bars are installed on top of the installed triple squares and cables, and one horizontal bar is placed on top of them in the center.

The frame parts are connected with screws with a diameter of 6 millimeters. When installing screws, use the holes left after unscrewing the screws connecting the top horizontal bar to the vertical bars. Sections of coaxial cable and parts of triple squares are enclosed inside a wooden structure, which reliably protects the soldering points from weather influences.

The gaps between the bars at the sides and ends are sealed using construction sealant “liquid nails”.

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

Galvanized wire, a pipe clamp, epoxy resin, and paint can be purchased at a building materials store. A coaxial television cable with a characteristic impedance of 75 Ohms should be selected with a central copper core and a double shield consisting of foil and braided copper cores. The best results can be obtained by using the largest diameter cable with the largest possible number of cores in the screen braid.

The distances between the elements of the phased array, the dimensions of the triple square and the length of the cable sections were selected through numerous experiments in order to ensure the reception of the largest possible number of television channels and at the same time the minimum possible dimensions, reducing the weight of the antenna and facilitating installation. Reception to the antenna is possible through obstacles from nearby trees. The antenna has a low windage. Thanks to the arrangement of the cables inside a sealed wooden frame, a long service life and protection from weather factors are ensured. The quality of the received image does not depend on the time of year or time of day.

Denisov Platon Konstantinovich, Simferopol

Loop antennas

A conventional loop vibrator can be transformed into a square frame, the perimeter of which is approximately equal to the wavelength (Fig. 1).

Rice. 1 Transformation of a loop vibrator into a square frame.

Antennas of this type are called loop or loop antennas. To receive television programs, two-element and three-element loop antennas are most often used, which are otherwise called “double square” and “triple square”. These antennas are characterized by their simple design, fairly high gain and narrow bandwidth.

Narrowband antennas provide frequency selectivity compared to broadband ones. Thanks to this, interfering signals from other television transmitters operating on channels close in frequency cannot penetrate the input of the television receiver. This is especially important in weak signal conditions. It often becomes necessary to receive a weak signal from a remote transmitter when there is a nearby powerful transmitter of another channel. Under such conditions, the frequency selectivity of a television receiver may not be sufficient. In addition, an intense interfering signal entering the first stage of the receiver (or antenna amplifier) ​​leads to cross-modulation of the useful signal by the interfering signal. It is no longer possible to get rid of this in subsequent cascades. Therefore, in such cases, narrowband antennas should be used.

A two-element loop antenna is shown in Fig. 2. The antenna frames have a square shape, and at the corners they can have roundings of an arbitrary radius, not exceeding approximately 1/10 of the side of the square. The frames are made of a metal tube with a diameter of 10-20 mm for antennas of channels 1-5 or 8-15 mm for antennas of channels 6-12. The metal can be any, but copper, brass or aluminum are preferable.

Rice. 2. Two-element loop antenna.

For the decimeter range, the frames are made of copper or brass rod with a diameter of 3-6 mm. The upper boom connects the middles of both frames, and the lower one is isolated from the vibrator frame and attached to a plate made of PCB or organic glass. The ends of the vibrator frame are attached to the same plate with screws and nuts, for which the ends can be flattened. Arrows can be made of metal or insulating material. In the latter case, there is no need to specially connect the frames together. The mast must be wooden, at least its upper part. The metal part of the mast should end 1.5 m below the antenna. The antenna frames are positioned relative to each other so that their geometric centers are on a horizontal straight line directed towards the transmitter.

The cable is connected to the ends of the vibrator frame using a quarter-wave short-circuited balun cable, which is made from the same cable. The cable and the cable must approach the antenna vertically from below, the distance between them must be constant along the entire length of the cable, for which you can use PCB spacers. You can also secure the cable and cable to the insulating plate to which the lower boom and the ends of the vibrator frame are attached. In this case, small holes are drilled in the plate, and the cable and cable are tied to it with nylon fishing line. It is not advisable to use metal fastening elements.

To ensure rigidity, you can make a loop of two metal tubes connected at the upper ends to the ends of the vibrator frame. In this case, the cable is passed inside the right tube from bottom to top, the cable braid is soldered to the right, and the central core is soldered to the left ends of the vibrator frame. The loop tubes in the lower part are closed with a jumper, by moving which you can adjust the antenna to the maximum received signal.
The dimensions of two-element loop antennas recommended for meter television channels are given in Table 1.

Table 1. Dimensions of two-element loop antennas for meter waves, mm

Numbers channels
	1450	1220
	1630	1370	1050
	1500	1260

B = 0.26L, P = 0.31L, A = 0.18L, where L - the average wavelength of the received frequency channel, which is given . The cable length for this antenna is taken from table 1(parameter Ш).

The dimensions of two-element loop antennas for decimeter waves are given in Table 2. Since in this range the antenna bandwidth covers several frequency channels at once, the dimensions are given not for one channel, but for a group of adjacent frequency channels.

The “double square” loop antenna has a higher gain (by about 1.5 dB) compared to a two-element “wave channel” antenna. The above applies to antennas having the same length. Antenna gain is largely determined by the distance between antenna elements. The optimal distances from this point of view are in the range of 0.12....0.15L.

Table 2. Dimensions of two-element loop antennas of decimeter waves, mm

Channels	IN	R	A	Sh
21- 26	158	170	91	152
27-32	144	155	83	139
33-40	131	141	75	126
41-49	117	126	68	113
50-60	105	113	60	101

The design of a three-element “triple square” loop antenna is shown in Fig. 3.

Rice. 3. “Triple square” antenna.

The antenna contains three square frames, and the director and reflector frames are closed, and the vibrator frame at points a - a" is open. The frames are located symmetrically, so that their centers are on a horizontal line directed towards the telecentre, and are attached to two booms in the middle of the horizontal sides. The upper boom is made of the same material as the frames. Practice has shown that the antenna works better if the lower boom is made of insulating material (for example, from a textolite rod). The upper boom is soldered to the frames, and the lower one can be attached to the frames. by filling the connection points with epoxy resin. The antenna is attached to a mast made of insulating material. As in the case of the “double square”, a quarter-wave short-circuited cable made from a piece of the same cable is used for balancing.

There is also a simple design of a three-element UHF loop antenna made from one piece of thick wire, shown in Fig. 4.

At points A, B and C, the wires must be soldered. Instead of a cable made from a piece of coaxial cable, a quarter-wave short-circuited bridge of the same length as the cable is used. The distance between the bridge wires remains the same - 30 mm. The design of such an antenna turns out to be quite rigid and there is no need for a lower boom. The cable is tied to the right wire of the bridge with

Rice. 4. “Triple square” antenna option.

outside. When the cable approaches the vibrator frame, its braid is soldered to point a, the central core to point b. The left bridge wire is fixed to the mast. You just need to pay attention to the fact that neither the cable nor the mast are located in the space between the bridge wires. You can also familiarize yourself with a description of the design of a three-element antenna made from one piece of wire , with design six-element - .

The input impedance of an antenna, as well as its gain, is also determined by the distance between the antenna elements. Figure 5 shows the dependences of the gain and input resistance on the distance between its elements.

For example, with a distance between the reflector and the vibrator of 0.11L, we obtain that the input impedance of the antenna is 65 Ohms, and the gain

Rice. 1.5. Dependences of the gain and input impedance of loop antennas on the distance between the elements (top figure: 1 - “triple square”, 2 - “double square”; bottom figure: 1 - single “square” antenna, 2 - “double square”, 3 - distance S = 0.11L corresponds to maximum gain).

compared to a half-wave dipole is 5.5 dB (for a “double square”) and 6.6 dB (for a “triple square”). It should be noted that the gain values ​​of loop antennas given in popular literature are greatly overestimated and reach 14 dB.

Two-element and three-element loop antennas have a fairly narrow main lobe and therefore must be carefully oriented.

The antenna is tuned by changing the length of the cable connected to the reflector. The most optimal length of the reflector is 4% longer than the length of the vibrator.

When calculating a triple square antenna, you can use the following formulas: B = 0.255L; P = 0.261L; D = 0.247L, where L is the wavelength. The optimal distance between elements is A = 0.11....0.15L.

Studies have shown that the transition from a two-element square antenna containing a vibrator and a reflector to a three-element antenna results in a gain of 1.7 dB. A similar procedure for a “wave channel” antenna gives a gain of 2.7 dB. It should also be noted that the “triple square” antenna has a narrower operating frequency band than the “double square” antenna. The dimensions of “triple square” antennas for the meter and decimeter wave bands are given in Tables 3 and 4.

For sufficient strength, the frames and upper boom of the meter wave antenna are made from a tube with a diameter of 10...15 mm, and the distance between the ends of the vibrator frame is increased to 50 mm.

Table 3. Dimensions of three-element loop antennas for meter waves, mm

Channel numbers
	1255	1060
	1485	1260
	1810	1530	1190	1080

Despite the rapid development of satellite and cable television, the reception of terrestrial television broadcasts still remains relevant, for example, for places of seasonal residence. It is not at all necessary to buy a finished product for this purpose; a home UHF antenna can be assembled with your own hands. Before moving on to considering the designs, we will briefly explain why this particular range of the television signal was chosen.

Why DMV?

There are two good reasons to choose designs of this type:

1. The thing is that most channels are broadcast in this range, since the design of repeaters is simplified, and this makes it possible to install a larger number of unattended low-power transmitters and thereby expand the coverage area.
2. This range is selected for digital broadcasting.

Indoor TV antenna “Rhombus”

This simple, but at the same time, reliable design was one of the most common in the heyday of broadcast television.

Rice. 1. The simplest homemade Z-antenna, known under the names: “Rhombus”, “Square” and “People’s Zigzag”

As can be seen from the sketch (B Fig. 1), the device is a simplified version of the classic zigzag (Z-design). To increase sensitivity, it is recommended to equip it with capacitive inserts (“1” and “2”), as well as a reflector (“A” in Fig. 1). If the signal level is quite acceptable, this is not necessary.

The material you can use is aluminum, copper, and brass tubes or strips 10-15 mm wide. If you plan to install the structure outdoors, it is better to abandon aluminum, since it is susceptible to corrosion. Capacitive inserts are made of foil, tin or metal mesh. After installation, they are soldered along the circuit.

The cable is laid as shown in the figure, namely: it did not have sharp bends and did not leave the side insert.

UHF antenna with amplifier

In places where a powerful relay tower is not located in relative proximity, you can raise the signal level to an acceptable value using an amplifier. Below is circuit diagram device that can be used with almost any antenna.

Rice. 2. Scheme antenna amplifier for UHF range

List of elements:

• Resistors: R1 – 150 kOhm; R2 – 1 kOhm; R3 – 680 Ohm; R4 – 75 kOhm.
• Capacitors: C1 – 3.3 pF; C2 – 15 pF; C3 – 6800 pF; C4, C5, C6 – 100 pF.
• Transistors: VT1, VT2 – GT311D (can be replaced with: KT3101, KT3115 and KT3132).

Inductance: L1 - is a frameless coil with a diameter of 4 mm, wound with copper wire Ø 0.8 mm (2.5 turns must be made); L2 and L3 are high-frequency chokes 25 µH and 100 µH, respectively.

If the circuit is assembled correctly, we will get an amplifier with the following characteristics:

• bandwidth from 470 to 790 MHz;
• gain and noise factors – 30 and 3 dB, respectively;
• the value of the output and input resistance of the device corresponds to the RG6 cable – 75 Ohm;
• the device consumes about 12-14 mA.

Let's pay attention to the method of power supply; it is carried out directly through the cable.

This amplifier can work with the simplest designs made from improvised means.

Indoor antenna made from beer cans

Despite the unusual design, it is quite functional, since it is a classic dipole, especially since the dimensions of a standard can are perfectly suitable for the arms of a decimeter range vibrator. If the device is installed in a room, then in this case it is not even necessary to coordinate with the cable, provided that it is not longer than two meters.

Designations:

• A - two cans with a volume of 500 mg (if you take tin and not aluminum, you can solder the cable instead of using self-tapping screws).
• B – places where the cable shielding is attached.
• C – central vein.
• D – place of attachment of the central core
• E – cable coming from the TV.

The arms of this exotic dipole must be mounted on a holder made of any insulating material. As such, you can use improvised things, for example, a plastic clothes hanger, a mop bar or a piece of wooden beam of the appropriate size. The distance between the shoulders is from 1 to 8 cm (selected empirically).

The main advantages of the design are fast production (10 - 20 minutes) and quite acceptable picture quality, provided there is sufficient signal power.

Making an antenna from copper wire

There is a design that is much simpler than the previous version, which only requires a piece of copper wire. We are talking about a narrow band loop antenna. This solution has undoubted advantages, since in addition to its main purpose, the device plays the role of a selective filter that reduces interference, which allows you to confidently receive a signal.

Fig.4. A simple UHF loop antenna for receiving digital TV

For this design, you need to calculate the length of the loop; to do this, you need to find out the frequency of the “digit” for your region. For example, in St. Petersburg it is broadcast on 586 and 666 MHz. The calculation formula will be as follows: L R = 300/f, where L R is the length of the loop (the result is presented in meters), and f is the average frequency range, for St. Petersburg this value will be 626 (the sum of 586 and 666 divided by 2). Now we calculate L R, 300/626 = 0.48, which means the length of the loop should be 48 centimeters.

If you take a thick RG-6 cable with braided foil, it can be used instead of copper wire to make a loop.

Now let's tell you how the structure is assembled:

• A piece of copper wire (or RG6 cable) with a length equal to L R is measured and cut.
• A loop of suitable diameter is folded, after which a cable leading to the receiver is soldered to its ends. If RG6 is used instead of copper wire, then the insulation from its ends is first removed, approximately 1-1.5 cm (the central core does not need to be cleaned, it is not involved in the process).
• The loop is installed on the stand.
• An F connector (plug) is screwed onto the cable to the receiver.

Note that despite the simplicity of the design, it is most effective for receiving “digits”, provided that the calculations are carried out correctly.

Do-it-yourself MV and UHF indoor antenna

If, in addition to UHF, there is a desire to receive MF, you can assemble a simple multiwave oven, its drawing with dimensions is presented below.

To amplify the signal in this design, a ready-made SWA 9 unit is used; if you have problems purchasing it, you can use homemade device, the diagram of which was given above (see Fig. 2).

It is important to maintain the angle between the petals; going beyond the specified range significantly affects the quality of the “picture”.

Despite the fact that such a device is much simpler than a log-periodic design with a wave channel, it nevertheless shows good results if the signal is of sufficient power.

DIY figure eight antenna for digital TV

Let's consider another common design option for receiving “digits”. It is based on classic scheme for the UHF range, called “Figure Eight” or “Zigzag” because of its shape.

Rice. 6. Sketch and implementation of the digital eight

Design dimensions:

• outer sides of the diamond (A) – 140 mm;
• internal sides (B) – 130 mm;
• distance to the reflector (C) – from 110 to 130 mm;
• width (D) – 300 mm;
• the pitch between the rods (E) is from 8 to 25 mm.

The cable connection location is at points 1 and 2. The material requirements are the same as for the “Rhombus” design, which was described at the beginning of the article.

Homemade antenna for DBT T2

Actually, all of the examples listed above are capable of receiving DBT T2, but for variety we will present a sketch of another design, popularly called “Butterfly”.

The material can be used as plates made of copper, brass, aluminum or duralumin. If the structure is planned to be installed outdoors, then the last two options are not suitable.

Bottom line: which option to choose?

Oddly enough, the simplest option is the most effective, so the “loop” is best suited for receiving a “digit” (Fig. 4). But, if you need to receive other channels in the UHF range, then it is better to stop at “Zigzag” (Fig. 6).

The antenna for the TV should be directed towards the nearest active repeater, in order to select the desired position, you should rotate the structure until the signal strength is satisfactory.

If, despite the presence of an amplifier and reflector, the quality of the “picture” leaves much to be desired, you can try installing the structure on a mast.

In this case, it is necessary to install lightning protection, but this is a topic for another article.

Buying a good antenna for your dacha is not always advisable. Especially if she is visited from time to time. The point is not so much the cost, but the fact that after a while it may not be there. Therefore, many people prefer to make an antenna for their dacha themselves. Costs are minimal, quality is good. And the most important point is that a TV antenna can be made with your own hands in half an hour or an hour and then, if necessary, can be easily repeated...

Digital television in the DVB-T2 format is transmitted in the UHF range, and either there is a digital signal or there is not. If the signal is received, the picture is of good quality. Due to this. for reception digital television Any decimeter antenna is suitable. Many radio amateurs are familiar with the TV antenna, which is called “zigzag” or “figure eight”. This DIY TV antenna can be assembled literally in a matter of minutes.

To reduce the amount of interference, a reflector is placed behind the antenna. The distance between the antenna and the reflector is selected experimentally - according to the “purity” of the picture
You can attach foil to the glass and get a good signal...
Copper tube or wire - best option, bends well, easy to bend

It is very simple to make; the material is any conductive metal: tube, rod, wire, strip, corner. Despite its simplicity, she accepts it well. It looks like two squares (rhombuses) connected to each other. In the original, there is a reflector behind the square for more reliable signal reception. But it is more needed for analog signals. To receive digital television, you can do without it or install it later if the reception is too weak.

Materials

Copper or aluminum wire with a diameter of 2-5 mm is optimal for this homemade TV antenna. In this case, everything can be done in literally an hour. You can also use a tube, corner, strip of copper or aluminum, but you will need some kind of device to bend the frames to the desired shape. The wire can be bent with a hammer, securing it in a vice.

You will also need a coaxial antenna cable of the required length, a plug suitable for the connector on your TV, and some kind of mount for the antenna itself. The cable can be taken with a resistance of 75 Ohms and 50 Ohms (the second option is worse). If you are making a TV antenna with your own hands for installation on the street, pay attention to the quality of the insulation.

Mounting depends on where you are going to hang it homemade antenna for digital television. On the upper floors, you can try to use it as a home decoration and hang it on curtains. Then you need large pins. At the dacha or if you take a homemade TV antenna to the roof, you will need to attach it to a pole. For this case, look for suitable fasteners. To work, you will also need a soldering iron, sandpaper and/or a file, a needle file.

Do you need a calculation?

To receive a digital signal, there is no need to count the wavelength. It is simply advisable to make the antenna more broadband in order to receive as many signals as possible. To do this, some changes were made to the original design (pictured above) (further in the text).

If you wish, you can make a calculation. To do this, you need to find out what wavelength the signal is broadcast on, divide by 4 and get the required side of the square. To obtain the required distance between the two parts of the antenna, make the outer sides of the diamonds slightly longer and the inner ones shorter.

Drawing of a figure-of-eight antenna for receiving digital TV

• The length of the “inner” side of the rectangle (B2) is 13 cm,
• “external” (B1) - 14 cm.

Due to the difference in lengths, a distance is formed between the squares (they should not be connected). The two extreme sections are made 1 cm longer so that you can fold the loop to which the coaxial antenna cable is soldered.

Making a frame

If you count all the lengths, you get 112 cm. Cut off the wire or whatever material you have, take pliers and a ruler, and start bending. The angles should be 90° or so. You can make a little mistake with the lengths of the sides - this is not fatal. It turns out like this:

• The first section is 13 cm + 1 cm per loop. The loop can be bent immediately.
• Two sections of 14 cm each.
• Two 13 cm each, but with a turn in the opposite direction - this is the point of inflection onto the second square.
• Again two 14 cm each.
• The last one is 13 cm + 1 cm per loop.

The antenna frame itself is ready. If everything was done correctly, there will be a distance of 1.5-2 cm between the two halves in the middle. There may be small discrepancies. Next, we clean the loops and the bend point to bare metal (treat it with fine-grain sandpaper), and tin it. Connect the two loops and crimp them with pliers to hold them tightly.

Cable preparation

We take the antenna cable and carefully clean it. How to do this is shown in step by step photo. You need to strip the cable on both sides. One edge will be attached to the antenna. Here we strip it so that the wire sticks out 2 cm. If it turns out more, the excess (later) can be cut off. Twist the screen (foil) and braid into a bundle. It turned out to be two conductors. One is the central monocore of the cable, the second is twisted from many braided wires. Both are needed and need to be tinned.

We solder the plug to the second edge. A length of 1 cm or so is sufficient here. Also form two conductors and tin them.

Wipe the plug in the places where we will solder with alcohol or solvent, and clean it with emery (you can use a needle file). Place the plastic part of the plug on the cable, now you can start soldering. We solder a monocore to the central output of the plug, and a multicore twist to the side output. The last thing is to crimp the grip around the insulation.

Then you can simply screw on the plastic tip and fill it with glue or non-conductive sealant (this is important). While the glue/sealant has not hardened, quickly assemble the plug (screw on the plastic part) and remove the excess compound. So the plug will be almost eternal.

DIY DVB-T2 TV antenna: assembly

Now all that remains is to connect the cable and the frame. Since we were not tied to a specific channel, we will solder the cable to the middle point. This will increase the broadband of the antenna - more channels will be received. Therefore, we solder the second cut end of the cable to the two sides in the middle (those that were stripped and tinned). Another difference from the “original version” is that the cable does not need to be routed around the frame and soldered at the bottom. This will also expand the reception range.

The assembled antenna can be checked. If the reception is normal, you can finish the assembly - fill the solder joints with sealant. If the reception is poor, try first to find a place where the fishing is better. If there are no positive changes, you can try replacing the cable. To simplify the experiment, you can use regular telephone noodles. It costs a penny. Solder the plug and frame to it. Try it with her. If it catches better, it’s a bad cable. In principle, you can work on “noodles”, but not for long - they will quickly become unusable. It is better, of course, to install a normal antenna cable.

To protect the junction of the cable and the antenna frame from atmospheric influences, the soldering points can be wrapped with ordinary electrical tape. But this method is unreliable. If you remember, you can put on several heat-shrinkable tubes before soldering to insulate them. But the most reliable way is to fill everything with glue or sealant (they should not conduct current). As a “case” you can use lids for 5-6 liter water cylinders, ordinary plastic lids for jars, etc. We make indentations in the right places - so that the frame “sits” in them, do not forget about the cable outlet. Fill it with a sealing compound and wait until it sets. That's it, your DIY TV antenna for receiving digital television is ready.

Homemade double and triple square antenna

This is a narrowband antenna, which is used if you need to receive a weak signal. It can even help if a weaker signal is “clogged” by a stronger one. The only drawback is that you need precise orientation to the source. The same design can be made to receive digital television.

You can also make five frames - for a more confident reception
It is not advisable to paint or varnish - reception deteriorates. This is only possible in close proximity to the transmitter

The advantages of this design are that reception will be reliable even at a considerable distance from the repeater. You just need to specifically find out the broadcast frequency, maintain the dimensions of the frames and the matching device.

Construction and materials

It is made from tubes or wire:

• 1-5 TV channel MV range - tubes (copper, brass, aluminum) with a diameter of 10-20 mm;
• 6-12 TV channel MV range - tubes (copper, brass, aluminum) 8-15 mm;
• UHF range - copper or brass wire with a diameter of 3-6 mm.

The double square antenna consists of two frames connected by two arrows - upper and lower. The smaller frame is a vibrator, the larger one is a reflector. An antenna consisting of three frames gives a higher gain. The third, smallest square is called the director.

The upper boom connects the middle of the frames and can be made of metal. The lower one is made of insulating material (textolite, gettinax, wooden plank). The frames must be installed so that their centers (the points of intersection of the diagonals) are on the same straight line. And this straight line should be directed towards the transmitter.

The active frame - the vibrator - has an open circuit. Its ends are screwed to a textolite plate measuring 30*60 mm. If the frames are made from a tube, the edges are flattened, holes are made in them and the lower arrow is attached through them.

The mast for this antenna must be wooden. At least the upper part of it. Moreover, the wooden part should start at a distance of at least 1.5 meters from the level of the antenna frames.

Dimensions

All dimensions for making this TV antenna with your own hands are given in the tables. The first table is for the meter range, the second is for the decimeter range.

In three-frame antennas, the distance between the ends of the vibrator (middle) frame is larger - 50 mm. Other sizes are given in the tables.

Connecting an active frame (vibrator) via a short-circuited cable

Since the frame is a symmetrical device, and it must be connected to an asymmetrical coaxial antenna cable, a matching device is required. In this case, a balancing short-circuited loop is usually used. It is made from pieces of antenna cable. The right segment is called the “loop”, the left one is called the “feeder”. A cable is attached to the junction of the feeder and the cable, which goes to the TV. The length of the segments is selected based on the wavelength of the received signal (see table).

A short piece of wire (loop) is cut at one end by removing the aluminum screen and twisting the braid into a tight bundle. Its central conductor can be cut down to insulation, since it does not matter. The feeder is also cut. Here, too, the aluminum screen is removed and the braid is twisted into a bundle, but the central conductor remains.

Further assembly proceeds like this:

• The braid of the cable and the central conductor of the feeder are soldered to the left end of the active frame (vibrator).
• The feeder braid is soldered to the right end of the vibrator.
• The lower end of the cable (braid) is connected to the feeder braid using a rigid metal jumper (you can use wire, just make sure there is good contact with the braid). In addition to the electrical connection, it also sets the distance between sections of the matching device. Instead of a metal jumper, you can twist the braid of the lower part of the cable into a bundle (remove the insulation in this area, remove the screen, roll it into a bundle). To ensure good contact, solder the bundles together with low-melting solder.
• The cable pieces must be parallel. The distance between them is about 50 mm (some deviations are possible). To fix the distance, clamps made of dielectric material are used. You can also attach a matching device to a textolite plate, for example.
• The cable going to the TV is soldered to the bottom of the feeder. Braid is connected to braid, center conductor is connected to center conductor. To reduce the number of connections, the feeder and cable to the TV can be made single. Only in the place where the feeder should end must the insulation be removed so that the jumper can be installed.

This matching device allows you to get rid of noise, blurry contours, and a second blurry image. It is especially useful at a great distance from the transmitter, when the signal will be clogged with interference.

Another variation of the triple square

In order not to connect a short-circuited loop, the triple square antenna vibrator is made elongated. In this case, you can connect the cable directly to the frame as shown in the figure. Only the height at which the antenna wire is soldered is determined in each case individually. After the antenna is assembled, “testing” is carried out. The cable is connected to the TV, the central conductor and braid are moved up/down, achieving a better image. In the position where the picture will be clearest, the antenna cable branches are soldered, and the soldering points are insulated. The position can be any - from the bottom jumper to the transition point to the frame.

Sometimes one antenna does not give the desired effect. The signal turns out to be a weak image - black and white. In this case standard solution— install a television signal amplifier.

The simplest antenna for a summer residence is made from metal cans

To make this television antenna, in addition to the cable, you will only need two aluminum or tin cans and a piece of wooden plank or plastic pipe. Cans must be metal. You can take aluminum beer beers, or you can take tin ones. The main condition is that the walls are smooth (not ribbed).

The jars are washed and dried. The end of the coaxial wire is cut - by twisting the braided strands and clearing the central core of insulation, two conductors are obtained. They are attached to banks. If you know how, you can solder it. No - take two small self-tapping screws with flat heads (you can use “fleas” for drywall), twist a loop at the ends of the conductors, thread a self-tapping screw with a washer installed on it through it, and screw it to the can. Just before this you need to clean the metal of the can by removing the deposits using fine-grain sandpaper.

The cans are secured to the bar. The distance between them is selected individually - according to the best picture. You shouldn’t hope for a miracle - there will be one or two channels in normal quality, but maybe not... It depends on the position of the repeater, the “cleanliness” of the corridor, how correctly the antenna is oriented... But as a way out in an emergency, this is an excellent option.

A simple Wi-Fi antenna made from a metal can

Antenna for reception Wi-Fi signal You can also make it from improvised means - from a tin can. This DIY TV antenna can be assembled in half an hour. This is if you do everything slowly. The jar should be made of metal, with smooth walls. Tall and narrow canning jars work great. If you will be installing a homemade antenna on the street, find a jar with a plastic lid (as in the photo). The cable is an antenna, coaxial, with a resistance of 75 Ohms.

In addition to the can and cable, you will also need:

• RF-N connector;
• a piece of copper or brass wire with a diameter of 2 mm and a length of 40 mm;
• cable with a socket suitable for a Wi-Fi card or adapter.

Wi-Fi transmitters operate at a frequency of 2.4 GHz with a wavelength of 124 mm. So, it is advisable to choose a jar such that its height is at least 3/4 of the wavelength. For this case, it is better that it be more than 93 mm. The diameter of the can should be as close as possible to half the wavelength - 62 mm for a given channel. There may be some deviations, but the closer to the ideal, the better.

Dimensions and assembly

When assembling, a hole is made in the jar. It must be placed strictly at the desired point. Then the signal will be amplified several times. It depends on the diameter of the selected jar. All parameters are shown in the table. You measure the exact diameter of your can, find the right stitch, and have all the right dimensions.

D - diameter	Lower limit of attenuation	Upper limit of attenuation	Lg	1/4 Lg	3/4 Lg
73 mm	2407.236	3144.522	752.281	188.070	564.211
74 mm	2374.706	3102.028	534.688	133.672	401.016
75 mm	2343.043	3060.668	440.231	110.057	330.173
76 mm	2312.214	3020.396	384.708	96.177	288.531
77 mm	2282.185	2981.170	347.276	86.819	260.457
78 mm	2252.926	2942.950	319.958	79.989	239.968
79 mm	2224.408	2905.697	298.955	74.738	224.216
80 mm	2196.603	2869.376	282.204	070.551	211.653
81 mm	2169.485	2833.952	268.471	67.117	201.353
82 mm	2143.027	2799.391	256.972	64.243	192.729
83 mm	2117.208	2765.664	247.178	61.794	185.383
84 mm	2092.003	2732.739	238.719	59.679	179.039
85 mm	2067.391	2700.589	231.329	57.832	173.497
86 mm	2043.352	2669.187	224.810	56.202	168.607
87 mm	2019.865	2638.507	219.010	54.752	164.258
88 mm	1996.912	2608.524	213.813	53.453	160.360
89 mm	1974.475	2579.214	209.126	52.281	156.845
90 mm	1952.536	2550.556	204.876	51.219	153.657
91 mm	1931.080	2522.528	201.002	50.250	150.751
92 mm	1910.090	2495.110	197.456	49.364	148.092
93 mm	1889.551	2468.280	194.196	48.549	145.647
94 mm	1869.449	2442.022	191.188	47.797	143.391
95 mm	1849.771	2416.317	188.405	47.101	141.304
96 mm	1830.502	2391.147	185.821	46.455	139.365
97 mm	1811.631	2366.496	183.415	45.853	137.561
98 mm	1793.145	2342.348	181.169	45.292	135.877
99 mm	1775.033	2318.688	179.068	44.767	134.301

The procedure is as follows:

You can do without an RF connector, but with it everything is much simpler - it’s easier to position the emitter vertically upward, connect the cable going to the router or Wi-Fi card.