A simple do-it-yourself DVB-T2 digital television antenna. Antenna Kharchenko: calculation and manufacturing

Good afternoon, V.Yu.
The visitor in the last posts with experience in FM radio antennas is me. The antenna turned out to be easy to manufacture and I decided to repeat it for FM reception and compare it with those previously made, by ear, according to instruments, ease of use. The goal was to obtain a signal with a minimum of interference for high-quality radio sound in stereo mode. Made two antennas. The first of the wire is 3 mm thick. The second is made of metal. From the metal-layer, it turned out to be slightly better in terms of the level of received signals. By ear - less low frequencies, more highs and the distinctness of each instrument in the orchestra.
Measurement method - there is a receiver with a signal level indicator in decibels. We number the stations of the FM band and look at the level of the received signal from the station in dB, then we summarize all the values. We get the numerical value of the antenna according to the received signal level parameter. All antennas were placed under the same conditions in direction. Wire on a window 303 cm long in the form of a rectangle with a gap along larger side in 2 cm (51 cm x 102 cm) - has a value of 491 dB, a directional loop phased loop antenna from a wire - 459 dB, the same from a metal-plastic - 485 dB. As can be seen from the presented values, the metal-plastic antenna is comparable to a full-size frame equal to the wavelength of the mid-FM band.
Now for the manufacturing technology. it is somewhat different from yours and is made without soldering. The base is a rail (30 x 6 x 3 cm). Remained from the repair (2 pcs). Wire antenna - circumference 75 cm (four-wave mid-FM range). Two circles of the same length. We take a light self-tapping screw (not dark - it has a cone head) with a flat head for a Phillips screwdriver. We make a hole in the rail with a drill or in another way so that the wire enters the hole with little resistance. You can slightly bend the ends of the wire for this purpose. We put the two ends of the loop into the hole of the rail and do not connect them together (leave 5 mm between the ends of the loop). We do the same with the second loop at the other end of the rail. The distance from the end of the rail is 1 cm. We screw the screws on top of the rail so that the end of the screw enters the loop wire at the end. This ensures the contact of the coax with the frame. Under the screws, we wind the central core of the coax and the braid from different sides of the frame. For example, the central core is on the left, and the braid is on the right in the direction from the beginning of the rail to its end. Between the frames we lay the coaxial and fasten it to the screws (we wind it under the screw head). The second loop is also fastened and the ends of the coax are fastened under the screws for fastening the second loop. The descent in the form of a coaxial - I got a length of 7.5 meters, we fasten it under the screws of one of the frames (the central core is on the left, and the braid is on the right. We tighten everything - the screws provide contact between the wires with a hat, and the end - contact with the loop. The distance between self-tapping screws - 2 cm We connect the other end of the coax to the receiver through the connector you need.That's it - the antenna is ready.
Metal-plastic differs in manufacturability. Pipe 20 mm, also after repair. It bent into a ring without problems. Loop length 75 - 1.5 cm (as recommended in the article) = 73.5 cm. Fastening the loop to the rail is also a self-tapping screw, but bigger size so that it passes through the metal-layer and is well fixed to the tree, by 10-15 mm. There is a distance of 1 cm between the ends of one loop. The screws are still at a distance of 0.5 cm from the end of the loop. We get a distance of 2 cm between the screws of one loop. We lay a piece of metal-plastic between the loops and fasten it with screws to the rail, so that coax can be inserted inside. We connect the coaxial in the same way as in the first case to the ends of the loop, the central core and the braid. We ground the tube between the loops of the antenna (we connect it with a braid). We put a piece of coax into the pipe between the loops, connect the c.zh. and braid. We also connect the reduction coaxial with the screws of one of the loops (c.zh. and braid). We pre-clean the ends of the loops from vinyl to aluminum so that the screw head presses the wires to the aluminum and at the same time fastens the loop to the wooden rail.
With all respect, Andrew

Despite the rapid development of satellite and cable television, the reception of terrestrial television is still relevant, for example, for seasonal residences. It is not at all necessary to buy a finished product for this purpose; a home decimeter (UHF) antenna can be assembled by hand. Before proceeding to the consideration of designs, we will briefly describe why this particular range of the television signal was chosen.

Why DMV?

There are two good reasons to opt for this type of structure:

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 set more unattended low-power transmitters and thereby expand the coverage area.
2. This range is selected for broadcasting "numbers".

Indoor antenna for TV "Rhombus"

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

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 acceptable, this is not necessary.

As a material, you can use aluminum, copper, as well as brass tubes or strips with a width of 10-15 mm. If you plan to install the structure on the street, then 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 contour.

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

Decimeter 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 a schematic diagram of a device that can be used with almost any antenna.

Item List:

• 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 25 µH and 100 µH high frequency chokes, 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 coefficients - 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 way the power is supplied, 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 perfect for the arms of a UHF 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, not aluminum, you can solder the cable, and not use self-tapping screws).
• B - places for fastening the shielding braid of the cable.
• C - central vein.
• D - the 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 quality of the "picture", provided that the signal strength is sufficient.

Making a copper wire antenna

There is a design that is much simpler than the previous version, which requires only a piece of copper wire. It's about about the narrow band loop antenna. This solution has undeniable 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.

For this design, it is necessary to calculate the length of the loop, to do this, you need to find out the frequency of the “numbers” for your region. For example, in St. Petersburg it is broadcast on 586 and 666 MHz. The calculation formula will be: 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 Peter 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 that the length of the loop should be 48 centimeters.

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

Now we will tell you how the structure is assembled:

• A piece of copper wire (or RG6 cable) is measured and cut off with a length equal to L R .
• A loop of a suitable diameter is folded, after which a cable is soldered to its ends, which goes to the receiver. If RG6 is used instead of copper wire, then the insulation is first removed from its ends, by about 1-1.5 cm (the central core does not need to be cleaned, it does not participate 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 "numbers", provided that the calculations are carried out correctly.

Do-it-yourself indoor antenna MV and UHF

If, in addition to UHF, there is a desire to receive MV, 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 block is used, if there are problems with its acquisition, you can use a home-made device, the circuit of which was given above (see Fig. 2).

It is important to observe 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, nevertheless, it shows good results if the signal is of sufficient power.

Do-it-yourself figure-eight antenna for digital TV

Consider another common design option for receiving "numbers". It is based on the classic scheme for the UHF range, which, due to its shape, was called the "Eight" or "Zigzag".

Construction dimensions:

• the outer sides of the rhombus (A) - 140 mm;
• inner sides (B) - 130 mm;
• distance to the reflector (C) - from 110 to 130 mm;
• width (D) - 300 mm;
• step between the bars (E) - from 8 to 25 mm.

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

Homemade antenna for DBT T2

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

As a material, you can use plates made of copper, brass, aluminum or duralumin. If the structure is planned to be installed on the street, then the last two options are not suitable.

Outcome: which option to stop?

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

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

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

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

In the days of huge tube TVs, a good antenna for high-quality analog TV reception was in short supply. Those that could be bought in stores were not of high quality. So people made television antennas DMV with your own hands. Today, many are interested in homemade devices. And even when digital technologies are everywhere, this interest does not fade away.

Digital era

This era also affected television. Today, T2 broadcasting is developing especially widely. It has its own characteristics. In those places where the signal level slightly exceeds the interference, a fairly high-quality reception is obtained. There is simply no further signal. digital signal no interference, however, in a situation of cable mismatch or various phase distortions, almost anywhere in the transmitting or receiving path, the picture can go in squares even with a strong signal level.

In modern television, other changes have taken place. So, all broadcasting is carried out in the UHF band, the transmitters have good coverage. The conditions under which radio waves propagate through cities have changed dramatically.

Antenna parameters

Before you start manufacturing, you need to determine some parameters of these structures. They, of course, require in-depth knowledge in various areas of mathematics, as well as the laws of electrodynamics.

So, the gain is the ratio of the power at the input of the reference system to the power at the input of the antenna used. All this will work if each of the antennas creates the values ​​of the intensity and flux density with the same parameters. Value given coefficient dimensionless.

The directional factor is the ratio of the field strength that the antenna produces to the field strength in any direction.

It must be remembered that parameters such as KU and KND are not interconnected. There is a UHF antenna for digital TV, which has a very high directivity. However, its enhancement is small. These designs are directed into the distance. There are also designs with high directivity. Here it comes in combination with a very powerful level of amplification.

Today, you can not look for formulas, but use special programs. They already take into account all the necessary parameters. You just have to enter some conditions - and you will receive a complete calculation of the UHF antenna, so that you can then assemble it.

Manufacturing nuances

Any structural element in which signal currents flow must be connected using a soldering iron or welding machine. Such a node, if it is in the open air, suffers from a breakdown in contact. From this, various antenna parameters and the reception level can become significantly worse.

This is especially true for points with zero potentials. According to experts, voltage can be observed in them, as well as current antinode. To be more precise, this is the maximum current value. Is it available at zero voltages? This is not surprising.

Such places are best made from solid metal. Creeping currents are unlikely to affect the picture if the connections are made by welding. However, due to their presence, the signal may disappear.

How and what to solder?

Do-it-yourself UHF antenna is not very easy to make. This involves working with a soldering iron. Modern television cable manufacturers no longer make it copper. Now there is an inexpensive alloy that is resistant to corrosion. These materials are difficult to solder. And if they are heated long enough, there is a risk of burning the cable.

Experts recommend using low-power soldering irons, low-melting solders, and fluxes. Do not spare the paste when soldering. The solder will lie correctly only if it is under a layer of boiled flux.

Catch T2

In order to enjoy digital TV, it is enough to purchase a special tuner. But it does not have a built-in antenna. And those that are offered as special digital ones are too expensive and meaningless.

Now we will learn how to catch T2 on a completely homemade design. Homemade UHF antenna - it's simple, cheap, high quality. Try it yourself.

The simplest antenna

To assemble this design, you will not even need to go to the store. For its manufacture, a conventional antenna cable is sufficient. You need 530 mm of wire for the ring and 175 mm from which the loop will be made.

The TV antenna itself is a ring of cable. The ends must be stripped, and then connected to the loop. And to the latter you need to solder a cable that connects to the T2 tuner. So, on the ring, the screen and the central core are connected to the screens of the loop. At the last, the central veins are also connected. And the cable to the tuner is soldered as standard to the screen and the central core.

So we got the UHF antenna, made with our own hands. Its construction turned out to be very cheap and practical. And it works no worse than expensive store options. It must be fixed on plywood or plexiglass. For this, construction clamps are perfect.

"People's" antenna

This design is an aluminum disc. The outer diameter of the element should be 365 mm and the inner diameter 170 mm. The disc must be 1 mm thick. First you need to make a cut in the disk (10 mm wide). In the place where he drank, you should install a printed circuit board made of textolite. It should be 1 mm thick.

The board must have holes for the M3 screws. The board must be glued to the disk. Then you need to solder the cable leads to it. The central core should be soldered to one side of the disk, the screen to the other. In terms of quality, such a TV antenna will receive better with two discs, especially if it is far from the TV repeater.

Universal Antenna

Nothing supernatural will be used to make this design. We will make it from various improvised materials. However, although it is homemade, it will work perfectly in the entire decimeter range. So, this UHF antenna, quickly made with your own hands, is in no way inferior to store-bought, more expensive designs. To receive T2, it will be enough completely.

So, to assemble this design, you will need empty cans of canned food or beer. You need 2 cans with a diameter of 7.5 cm. The length of each is 9.5 cm. You also need to stock up on strips of textolite or getinax, always with foil.

Our cans need to be connected to the textolite strips using a soldering iron. The plate of this material, which will connect the containers at the top, must be completely covered with copper foil. On the bottom plate, the foil should be cut. This is done for easy cable connection.

It is necessary to assemble the structure in such a way that the total length is not less than 25 cm. This antenna (UHF band) is a broadband symmetrical vibrator. Due to its surface area, it has large gains.

If suddenly you cannot find suitable jars, then you can use containers with a smaller diameter. However, then the foil will have to be cut on the upper connecting plate as well.

"Beer" antenna

Love to drink beer? Don't throw away cans. You can make a good antenna out of them. To do this, you need to fix two beer cans on any dielectric material.

First you need to choose the right cable, and then bring it to mind. To do this, the cable must be stripped. You will see shielding foil. There will be a protective layer underneath. But under it, you can directly observe the cable.

For our antenna, you need to strip the top layer of this wire by about 10 cm. The foil must be carefully twisted to end up with a branch. protective layer for the central core, you need to strip it by 1 cm.

On the other hand, you need to solder the plug for the TV to the cable. If you were a subscriber of cable networks, then this part and cable will not even have to be purchased separately.

Now for the cans. It is advisable to use beer containers with a volume of 1 liter. However, good German beer in such cans is expensive, and domestic beer is not sold.

Banks must be opened very carefully. Then you need to free the container from the contents, and then dry it well. Next, use a self-tapping screw to connect our screen on the cable and the jar. To the second you need to fasten the central core.

For more High Quality images, it is better to connect the containers and the cable with a soldering iron.

It is necessary to fix the banks on some dielectric material. It should be noted that they should be located on the same straight line. The distance between them depends on the capacity. All this is selected only by experience.

Zigzag

The UHF zigzag antenna has a maximum simple design. The item itself is broadband. Its device allows you to allow various deviations from the original design parameters. At the same time, its electrical parameters are almost not violated.

Its input resistance in a certain range depends on the size of the conductors that will form the basis of the web. There is a dependency here. The greater the width or thickness of the conductors, the better the antenna will be matched to the feeder. In general, any conductors can be used to make a web. For this, plates, and tubes, and corners, and much more are suitable.

In order to increase the directivity of such an antenna, it is permissible to use a flat screen, which will play the role of a reflector. The latter will reflect high-frequency energy towards the antenna. Such screens are often large, and the phase depends mainly on the distance.

On the practical side, the reflector is only rarely made from a single sheet of metal. More often it is made in the form of conductors that are connected in the same plane. For design reasons, it is not necessary to make a screen that is too dense. The conductors from which the screen itself will be made are attached by welding or soldering to a metal frame.

This design is made very simply. It works well in the UHF range. In the USSR, it was a real folk irreplaceable model. It has a small size, so it can be used as a UHF indoor antenna.

The material will be copper tubes or aluminum sheet. The side parts can be made of solid metal. Often they are tightened with a net or covered with a tin. If one of the indicated methods is used, then the structure should be soldered along the contour.

The cable must not be bent sharply. How to carry out this element, you can see in the pictures presented.

It must be guided in such a way that it reaches the side corner, but does not go beyond the antenna or side square.

Indoor antenna MV UHF

This design is designed to receive signals easily and confidently. digital television. It can be made easily and very quickly. To do this, you need an aluminum or copper bar. Its length should be up to 1800 mm. This antenna can also be used as an outdoor antenna.

The design is a frame in the form of a rhombus. There should be two. One acts as a vibrator, the second works as a reflector. To receive T2, it is necessary that the side of our rhombus is approximately 140 mm, and the distance between them is 100 mm.

After the frame is made and the structure becomes rigid, a dielectric is mounted between the two ends of our rod. It could be anything. Shape and size are completely irrelevant. The distance between two points of the bars should be approximately 20 mm. The upper parts of our rhombuses need to be connected.

The feeder can be made from a cable. It must be connected to brass or copper petals, which should already be fixed on the antenna output.

If the resulting design does not meet your expectations, for example, poor reception quality or the repeater is far away, you can supply the antenna with an amplifier - and as a result you will get an active UHF antenna. It is used both in the city and in the country.

The simplest UHF loop antenna

This design resembles the number "zero". By the way, this is the coefficient of its amplification. It is ideal for T2 reception. This part is able to work better than the products that are offered in stores.

It is also called digital, because with it you can perfectly catch digital broadcasts. It is narrowband, and this is a significant advantage. It works on the principle of a selective valve, which allows us to talk about reliable protection against interference.

For assembly, you will need an ordinary coaxial cable with a resistance of 75 ohms, as well as a regular TV plug. It is better to choose a cable with a large diameter of all options. As a stand, you can use a cardboard box or something else.

How long the frame will be, we determine using programs for calculating antenna parameters. The material for the manufacture of the frame can be used the same as in the cable. By the way, for calculations it is necessary to know the frequencies digital broadcasting In your city.

The central core of the cable in the frame design is not needed. The stripped wire is twisted together with the core and braid of the frame. Then this connection must be soldered.

The structure must be placed on a dielectric base. Better to keep it away from your tuner. It is important that there is no voltage at the antenna input.

So, we found out how the UHF antenna is made with our own hands. As you can see, this is not such a difficult task. But now you can watch your favorite TV shows in digital quality. And such a design is installed in the same way as a regular store - on the roof. You can use screws or bolted connection. It should be installed in a safe place so that during gusts of wind it does not fly off along with a piece of slate. It is desirable that the antenna is mounted at the highest possible height. Thus, you will exclude the appearance of interference during the display of cable or digital television.

With DVB-T2 support, and of course, he needed an antenna, which naturally needs to be made by hand. How to make an antenna for DVB-T2 with your own hands will be discussed further.

To begin with, I decided to test the Kharchenko biquadrat antenna, or simply the "eight" in common people. For manufacturing, we need a copper or aluminum wire with a diameter of 2-5 mm. I had a 2.5 square VVG at hand and I decided to try to make an antenna for DVB-T2 from it.

Antenna calculation

We will find out our frequencies of both DVB-T2 packages in our area. For this you can go to the website of the Interactive map of CETV and see which tower is closer to you, one or both packages of channels are broadcasting and at what frequencies. In our suburbs of St. Petersburg, these are 586 MHz and 666 MHz.

Now, knowing the packet frequencies, we need to calculate the length of the side of the square of our DVB-T2 antenna. It is equal to a quarter of a wavelength.

That is, for our 586MHz: 300000000/586000000=0,51 meter. Quarter wavelength respectively 0,51/4=0,127 meters or 12,7 cm.

For the second 666 MHz multiplex, we calculate similarly and get 11,2 cm.

We are interested in L1. H and B for an antenna with a reflector (grid), amplifies the signal. I did without it.

Now if we make an antenna for two DVB-T2 channel packages, we determine the average length. That is, we add our lengths and divide in half.

L1=(12.7+11.2)/2=11.95 round up to 12 cm.

Antenna assembly for DVB-T2

Everything should be clear here. We take our segment of VVG or whatever you have. To determine the approximate length of the wire needed to assemble the antenna, you can L1 * 8 and throw a couple of centimeters. 12*8+2=98 cm was needed to make my antenna.

If you have a thick wire 4-5 mm in diameter, then most likely you will not be able to do without a vice. I had enough pliers.

We clean the wire from insulation. Then bend the biquadrat with pliers. Let's see the pictures. All angles are 90 degrees.

Then solder the 75 ohm TV cable. We solder the core to one square, the braid to another.

The signal at high frequencies propagates along the surface of the conductor, so it is better to paint the antenna after assembly. I used leftover acrylic facade paint. It is better to fill the place of soldering with hot-melt adhesive or sealant.

We fasten the wire from the place of soldering with ties (straps) along the sides of the square, as in the photo. This mandatory action is the antenna match.

Testing a homemade antenna on a homemade TV

So the biquadrate gives a signal amplification of the order of 6 dB, and up to the tower 26 km in a straight line. Although the CETV website indicates that we are in the zone of a confident signal, I doubted and prepared what I had done a long time ago.

He climbed to the second floor of the house and pulled out the antenna to the scaffolding. He pointed towards the tower and turned on the TV. The TV confidently received both digital TV packages.

I brought a homemade antenna into the house, the TV continued to confidently show perfectly.

Since January 2015, the third multiplex has been switched on in Moscow and the Moscow region(!) on channel 34, whose programs are now selected by tender. Permanent programs of the 3 multiplex are: Match! Arena, Music of the First And life news. You can see the list of programs that participate in the tender.

(!) On channel 58 (770 MHz) since October 2016, a test broadcast of an ultra-high-definition signal (Ultra HD 4K) has been conducted. The signal can be received by any resident of Moscow and the nearest suburbs if there is a TV with Ultra HD/DVB-T2/HEVC support.

You can choose the receiver type.

A device for the most accurate tuning of digital terrestrial (DVB-T/T2) antennas.

Long Range DVB-T2 Antennas

DVB-T2 Balcony Antennas

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		Small Antenna with Built-in Amplifier +5 V. Designed to receive television signals in the UHF range. Easily mounted on the wall (using a bracket) or directly on the balcony grille in apartments for broadcasting DVB-T2 digital terrestrial television.