Drawing of an indoor UHF airplane antenna. How to make a decimeter antenna with your own hands

Modernization of the "Polish" antenna for T2

You can use the “Polish” antenna completely assembled with an amplifier without modification, but as experience shows, some frequency channels have a weak signal level.

We are all surprised by the versatility of the “Polish” antenna, and the Polish antenna is nothing more than the simplest combination of the simplest universal “butterfly” antenna, widely known since the 60s, with a vibrator length of 1150 mm and an opening angle of 38° for reception from 1 to 12 th channel in line of sight conditions

and a primitively designed “wave channel antenna”, and not a single size fits into any calculations or GOSTs. That is, we have a usual, practically, dummy UHF antenna in a “Polish” antenna for UHF reception (I’m talking about directors-passive selectors). It turns out that in this antenna only a “butterfly” works, or rather several “butterfly”-active selectors and I will also note those designed for a certain range (they are all the same length), and an SWA amplifier.

If you remove the SWA amplifier, the antenna will not work. What I am saying is that it is enough to bend such an active vibrator of certain sizes (we will talk about this below), connect the SWA amplifier. To balance the RF, you need to run the cable along the arm of the vibrator according to Fig. 2. Effect we'll get a much better "Polish"

ATTENTION: the cable is routed along the arm of the active vibrator that is connected to the “body” of the amplifier circuit! At the midpoint of the vibrator, where the HF potential is zero, we bend the cable smoothly and direct it along the traverse, then downward.
In short, any homemade antenna + SWA amplifier works much better than any “Polish”.

But we already have what we have. Let’s try to bring it a little into a normal UHF form. “Meter” mustaches (long active vibrators, see Fig. 1) are absolutely not needed; if we use an antenna for T2 (UHF wavelength), they can be cut to the same length as decimeter active vibrators. If one of the received channels is weaker than the others, you should try to remove the reflector sheet from the active vibrators. When adjusting the antenna in this way, its output impedance increases and the frequency response changes. Changing the antenna impedance does no harm at all, since the input impedance of the amplifier is higher than the antenna impedance. Radio amateurs who have experience working with antenna amplifiers can remove the matching-balancing elements on the ferrite ring from the amplifier circuit, this will expand the operating range active antenna. One of the antenna input terminals is connected to the amplifier input, and the second is connected to the “case” of the amplifier circuit.
The antenna resistance at equal received power is related to the output voltage

P=U2/R. U=(P*R)½.

This leads to the conclusion that it is necessary to increase the output impedance of the antenna (the input impedance of the amplifier is greater than the impedance of the antenna). Antennas with a resistance higher than 300 ohms can be successfully used. This connection method is also suitable for a wide-range antenna of the “wave channel” type (more on this later), and in a log-periodic antenna the output cable is balanced, passing through the antenna element (according to the principle of Fig. 2).
Somehow I have a lot of abstruse anecdotes, you’ll think that I’m as smart as.... No, it’s all simple - should you google mine?
I'll try to keep it simpler
I don’t recommend trimming “long mustaches” if you’re doing it for yourself, if you’re lazy, or for your “uncle,” I advise you to shorten it based on L (Length of the vibrator) = 1/2j (half the average length of the weak frequency channel)
And for ourselves, we bend two diamonds and remove the reflector from the back of the diamonds, or insert the sleeve into the mount and bend it 10 cm

Now let’s do some magic with the directors. I have already mentioned the “wave channel” antenna, this miracle is known from the times of black and white TV

So let’s take the dimensions of the directors and the distances between them from the “grandfather’s” antenna, proven over the years.

Vibrator no. length in mm distance in mm
7…………………………..107...............0
6…………………………..129..............80
5…………………………..155..............94
4…………………………..186..............77
3…………………………..225..............63
2…………………………..272..............53
1…………………………..330...............43
0....................................... ...........35

High-quality MV-UHF antenna "wave channel" with your own hands

This type of antenna refers to targeted UHF antennas.
Since the gain of the targeted UHF antenna is better than that of the Polish-array, it was decided to make a “hybrid” from the old domestic UHF antenna and the ASP-8 Polish-array with its amplifier. It worked! The image quality of weak images has improved noticeably. The idea of ​​making it was proposed somewhere by someone, all that remained was to implement it.

I will tell you simply, without any abstruse expressions and formulas.

For self-made antennas needed:

Special program to calculate Antwu15;

1 or 2 amplifiers from the grid (with housings);

Aluminum pipe cross section? o 25mm and length? 2m. (traverse);

3 aluminum tubes with a cross-section of up to o10mm, two lengths of 1m each (MV) and another? 2.5-3m. (for cutting UHF elements);

2 sheets of textolite 3-5 mm thick, dimensions: 300mmx150mm (for mounting MV);

You will also need self-tapping screws (20 pcs 15 mm) and bolts with nuts (thread x3 6 pcs 20 mm) (for fastening DMV and MV elements);
Attention What is critical here is the distance from the active vibrator “two diamonds” or “butterfly” (cut off long mustaches) as someone did, also for other “butterflies” to the first director (unless of course there is a desire to change the wires (tubes), here segments from long mustache
The last figure shows the dimensions and distances for channel frequencies in the band 21... 41. For other frequency channels, the dimensions can be calculated using the Antwu15 () program

So, first, let's look at the program. With its help, you can calculate various antenna options tuned to different bands. Let's launch. We are only interested in the first point

It's simple. We enter the data to which the antenna will be configured, and the program will do everything itself.

For example:

The center frequency of the antenna implies the broadcast frequency of the last 61-69 channels. The number of elements determines the length of the traverse. We set the diameter of the elements to 1-5 (not so significant).

The method of fastening the elements is through a traverse. We agree, and as a result we get ready-made sizes for our product.

Below is the result obtained, based on which one of the UHF antenna options was made. This option ensures stable signal reception from a tower 80 km away through splitters for two TVs and a PCI-TV tuner in a computer.

All that remains is to assemble. The length of the antenna is determined by the number of elements
I advise you to install directors for one frequency range on each “butterfly” (they will all be the same length) - four “butterflies” correspond to four frequency channels Ukraine

Here is another table of director lengths for a universal log-periodic antenna (counting from the “butterfly”) with 21....64

We discussed how to use the program above.
We get the dimensions calculated by the program. All that remains is to assemble. The length of the antenna is determined by the number of elements, you can calculate 1.4 m, but the gain will be less. IN overall choice behind you.

To obtain better shielding from the reflected signal, the role of a reflector can be performed by a grid-screen from the ASP-8 “Polish” antenna, dimensions: length - as in the calculation of the program, height 300 mm. Curved edges point forward. You can also use other material in the form of sheet iron, aluminum, or use it from old UHF antennas.

Now we prepare the MV antenna from two meter vibrators. It's much easier here. Its role will be played by 2 tubes with a cross-section of 10 mm and a length of 1 m, folded at an unfinished angle of 120 degrees. This part of the antenna can not be assembled if we do not need strictly meter waves for T2. And what kind of antenna do we have?
Here is a sketch of the resulting “monster”:

Well, let's go back to our "rams" - let's finish assembling the antenna.
Next we take the traverse. We make its length 5 cm longer for attaching the MV antenna. The traverse is an aluminum tube with a cross-section. 25mm. and make notches on it in the places where the elements, loop vibrator and reflector are attached. Distance according to the calculated table. We drill 10mm holes through them at right angles and insert elements into them. You can attach elements in different ways: using self-tapping screws on top, cutting threads in the elements with bolts, or putting rubber tubes on the elements, insert them tightly into the holes of the traverse.
The heart of the antenna is a loop vibrator, which can be made from an aluminum plate 13mm wide, or an aluminum or copper tube with a cross-section of 10mm.
The size of the loop vibrator is selected experimentally, already on the assembled antenna.

Simple DIY UHF television antenna

Assembly:

To assemble this antenna, you don’t even have to go shopping.
To do this you need to take antenna cable RK75 length 530mm (for ring) and 175mm. (for loop).
Connect as shown in the figure.

Do-it-yourself UHF television antenna “Narodnaya”

The antenna is an aluminum disk with an outer diameter of 356mm and an inner diameter of 170mm. and 1mm thick, in which a 10mm wide cut is made.
A printed circuit board made of glass lite 1mm thick is installed in place of the cut. This board has two holes for mounting with M3 screws.
TO printed circuit board attached to the antenna, solder the leads of the matching transformer T1.
For a transformer, it is best to use a ring core with an outer diameter of 6...10mm, and an inner diameter of 3...7mm. and thickness 2...3mm.
The transformer windings are covered with a single-layer insulated wire with a diameter of 0.2...0.25 mm. and have the same number of turns, from 2 to 3 turns. The length of the coil bends is 20mm.
With such a transformer, reception in the meter and decimeter range is possible at a distance of 25...30 km. At a distance of up to 50 km. The antenna works satisfactorily only on decimeter channels.
Without a transformer, the distance of reliable reception is halved.
However, there is a circuit that allows you to get similar results without a transformer; to do this you need to assemble the following circuit:

Here, too, you can use an SWA amplifier (we put an SWA amplifier instead of a transformer) and a power supply to it. But as experience shows, a transformer to which we supply power from the power supply from a “Polish” is better.

UHF television antenna with a simple do-it-yourself reflector

1. frame made of aluminum strips
2. amplifier
3. mast
4. reflector
A. Braid soldering point
B. soldering point of the central core

Assembly:

1. First, a frame is assembled from aluminum plates, overlapping, as shown in the figure, using bolts (after fastening, the fastening points should be painted with paint to avoid oxidation).
2. Next, a coaxial cable is soldered at points A and B.
3. bolt the frame to the mast
4. make from rods with a diameter of 3...10 mm (or you can simply use a reflector from a collapsed polish or reinforcement for peeling walls), attaching the reflector to the mast with brackets
5. Attach the amplifier to the mast and connect the coaxial cable to it.

Assembly is possible without a reflector, but the gain of such an antenna will be lower.

Do-it-yourself UHF television antenna with a complex reflector

Assembly:

1. first of all, the frame is assembled from aluminum plates, as for a simple reflector
2. Next, a reflector of the “dilapidated box” type is assembled as shown in the figure (the design of such a reflector can be very different, it all depends on your capabilities).
3. The reflector is attached to the mast with metal brackets
3. Next, the amplifier is attached to the mast, and the coaxial cable is soldered, the same as for a simple reflector.

On decimeter waves in the range 470-638 MHz (channels 21-41), directional antennas can be used as indoor antennas, since their sizes at these waves are relatively small. As directional indoor antennas for decimeter waves, the most convenient antennas are the “wave channel” type.

Figure 1 shows appearance indoor UHF antenna ATKD-2 of the “wave channel” type, operating without tuning on channels from 21 to 41 in the range 470-638 MHz. The geometric dimensions of the antenna are shown in Fig. 2a. The antenna consists of a base with a stand and a removable antenna sheet. The antenna sheet contains an active vibrator 1, a reflector 2 and two directors 3 and 4, which are made of brass or steel tape and attached to a plastic boom.
The reduction cable 5 is connected to the antenna through a short-circuited balun bridge (Fig. 2, b), the length of which is equal to a quarter of the wavelength at the middle frequency of the range 470-638 MHz. The bridge is formed by a two-wire line, one conductor of which is the metal screen of the reduction cable, the second is section 6 of the mounting wire MGShV with a cross-section of 0.35 mm2. At a distance of 140 mm from the antenna input terminals, equal to the required bridge length (a quarter wavelength at a frequency of 550 MHz), the mounting wire is soldered to the cable screen. The gain relative to a half-wave vibrator is at least 5.5 dB.
Here is another option for bending the “long mustache” of the Polish antenna and replacing the directors (for the range 42...64 we calculate the length and distance using a program)

Do-it-yourself UHF television log-periodic antenna

Added after 53 minutes 13 seconds:

Do-it-yourself universal car television antenna

All-wave car TV antenna with pie chart directivity in the horizontal plane. This antenna can also be used in stationary conditions, i.e. not only in a car, but also for home TV. You can also take the modernization of the “Polish” antenna as a basis - bend the “long mustache” with a ring of a certain diameter, or rather bend it like this, connecting with the neighbor’s butterfly - this is one mustache, and the second bend as in Indoor UHF antenna “wave channel” active loop vibrator for example (remember, the size is taken to be 1/2 the wavelength of the poorly indicating range)

car television antenna consists of
1. 2 aluminum rings (d=270mm and d=130mm)
2. wooden slats (3x3cm)
3. TV cable

Assembling a car television antenna
Such an antenna can be built using a commercially available 300/75 Ohm plug (see figure) with a matching transformer inside it for imported TVs.
Two aluminum rings are attached to the plug using the screws on it: one with a diameter of 270 mm for the UHF range (channels 6-12), the other with a diameter of 130 mm for the UHF range (channels 23-51). Since the MV ring is not suitable for us (we need a channel range of another 51...64), we change it to a calculated one with a diameter of 90 mm. The antenna made in this way is attached to a wooden rail with a cross-section of 3x3 cm with a hole for a plug plug. The plug is attached to the rail with electrical tape, and the rings are secured with two insulators to give rigidity to the system. The rail is bolted to the trunk frame located on the roof of the car. Using a standard industrial cable (plug-socket) RK-75-4-11, the antenna is connected in the rear compartment of the car to the car TV.
To increase efficiency, the antenna can be equipped with an amplifier (SWA-7 or SWA-9) powered by a car battery.

Do-it-yourself universal “can” UHF television antenna

The proposed antenna uses available materials. But, nevertheless, it operates in the entire UHF TV range, and is not inferior in parameters to a standard six-element log-periodic antenna produced in series.
To make this antenna you will need two empty tin cans with a diameter of 7.5 cm, a length of 9.5 cm and two small strips of filtered fiberglass.
The cans are connected by strips of fiberglass by soldering. The top strip is solid, and the foil on the bottom is cut (as shown in the figure)

for connecting a 75-ohm power cable.
The total length of the antenna for operation in all UHF channels must be at least 25 cm.
This antenna is something like a symmetrical broadband vibrator. Due to the large surface area, it has a high gain. When using small-diameter cans, it is necessary to make a cut in the foil in the top strip.

Added after 16 minutes 44 seconds:

Do-it-yourself UHF frame television antenna

The basis is a three-frame antenna. To make an antenna, any wire made of copper, brass, steel, aluminum, etc. with a diameter of 3...8 mm is taken and bent according to the pattern. The wires are soldered at the joints. The antenna cable is soldered to points A and B. At point C, the cable braid is connected to the antenna material.
You can take this antenna as the basis for modernizing the “Polish” antenna - bending the long mustache in the form of an average square, taking into account that B (Polish) = 1/2 B (frame)

10.10. UHF antennas

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

Table 10.20

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

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

Broadband antenna of the “Wave Channel” type for reception in channels 21...41(Fig. 10.32).

Depending on the distance to the TV transmitter and the area confident reception for its signals, the number of antenna elements (directors) can be reduced to 8,11 or 15.

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

Table 10.21

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

Kp=530/fcp

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

Kp=530/562=0.943.

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

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

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

Wave channel antenna with complex passive reflector(Fig. 10.34; Table 10.22...10.24) consists of a lattice reflector (Fig. 10.35, a), two blades of which are installed at an angle of 90° at the end of the carrier boom, an active loop vibrator (Fig. 10.35, b) and 18 directors.

In this case, the first two directors (A1 and D2) are two-story and spaced vertically by the thickness of the supporting boom (Table 10.23).

Table 10.22

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

Table 10.23

Table 10.24

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

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

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

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

The feeder is tied to the right wire of the bridge from the outside. When the feeder approaches the vibrator frame, the cable braid is soldered to point X"; the central conductor is soldered to point X. The left wire of the bridge is fixed to a dielectric stand or, in the case outdoor antenna- on the mast. It is important that the feeder and mast stand are not located in the space between the bridge wires.

If there are copper, brass or aluminum strips

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

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

The simplest reflector is flat screen made from tubes or pieces of thick wire. The diameter of the reflector elements is not critical (3...10 mm). The reflector sheet (2) is secured using support posts (3)

Table 10.25

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

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

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

Bread and circuses - this is what the Roman poet and satirist Juvenal said, and in some ways he was absolutely right. Modern society, and in particular the modern person, can no longer do without pretentious pictures, shocking videos, exciting films, and comedy skits. One of these “elements” that can provide us with access to the world of entertainment is television. But even here it is not enough to have a TV, it also needs to have an antenna. After all, without a blooming antenna, radio waves are as difficult to catch as a fish on a hook without bait. What an antenna is needed for is not only prosaic to say, especially since we have already mentioned this in a utilitarian manner, but more disrespectful to our reader. So, skipping the description of the antenna's purpose, let's proceed to the description of its creation. We wanted to talk about how to make an antenna with your own hands in this article.

Below we will present one of the simplest and, most importantly, affordable ways to make an indoor antenna for your TV. It is made utilitarianly out of nothing, or rather - 2 beer cans, self-tapping screws, a dress hanger, a wire and a plug.

DIY TV antenna made from beer cans

So, we need a couple of beer cans, a soldering iron, tv cable, solder and something else. More on this in the course of our story.

Here you need to know in what sequence and what to do to get the much desired TV antenna. If we talk about the requirements for the materials used to make the antenna, then first of all, buy a good television cable. A good television cable requires a resistance of 75 ohms per meter, a strong central core and dense continuous double shielding. How much cable to buy depends on the location of the antenna, but know that the longer the cable, the more “useful” signal will be canceled out in it. (the rule clearly works for MV shafts). For UHF it also works, but is not so critical.

So, we make a cut for the plug and install it on the wire.

The plugs are now such that they don’t even require soldering, so everything will depend on the accuracy of your cuts and the size (diameter) of the cable. The photo shows a not very good option for installing a plug on the cable going to the antenna, try to do it better. In principle, a lot of detail about installing a plug on a television cable can be found in the article “How to insert a plug onto a cable to connect to a TV.”

Next, let's start working on the second TV cable cover. Here you need to bring out 2 cable conductors, one from the very edge, and the second after about 10-15 cm. The first conductor is considered the core, the second is shielding. Here you will also need to be careful not to cut through unnecessary layers of insulation and conductors. As a result, the efficiency of the antenna and the clarity of reception of television channels will depend on the quality of each and the total of all works - remember this. In the photo below you can see how the first and second conductors are removed from the cable. The top insulation is dropped to a distance of 10-15 cm from the edge of the cable.

Now about beer cans. We don't know what kind of beer you can afford and like, but cans are needed more. We repeat, not many, but big ones. 0.75 is good, but liter ones are even better. It’s hard to say anything about the 5 liter kegs of beer. This will probably go beyond the “framework” of an indoor antenna. After drinking beer, rinse the jars in water and dry them so that the aroma of the intoxicating drink does not change from them. Such a smell will not attract radio waves, but it certainly will attract flies.
Now we take the cable that we prepared earlier. Using small self-tapping screws, we fasten one conductor to the end of the first can, the other to the end of the second. To improve contact between the can body and the screw, use solder. Fill any possible gaps to improve contact.

Now our antenna is almost ready, we don’t have enough frame to base the cans together and to attach the antenna to something. In our case, the frame was a dress hanger. There are all criteria “FOR” for this. Low price, availability, proper rigidity and size. Yes, there is also a hook to hang everything at once in the chosen place.
So, we place the jars on one level surface, so that they are symmetrical relative to the center. “Play around” a little with the distance between them, since the quality of signal reception will depend on this. You can secure the cans with tape or tape. The standard distance for cans on the antenna is about 75 mm.

As a result, we get a not crafty, but functional thing - an indoor television antenna made from beer cans. Of course, such an antenna is only capable of operating in an area with reliable coverage. TV signal. This is not an antenna for receiving a signal 20 km from the city, this is just something that will slightly make the reception more confident, but not ideal.
Professionals, perhaps, are already laughing sarcastically at this article and the antenna, because in fact, a television antenna requires a severe and precise calculation of its elements, depending on the received wavelength. In this they are absolutely right. But this calculation is not always accessible to the average person, which encourages him to undertake similar adventures in making antennas, such as in particular for the antenna shown here, from beer cans.
Next, we will consider a more serious option. First of all, its big advantage is that it will tell you how to make an antenna according to all the rules, taking into account the physiological characteristics of the propagation of radio waves.

Radio waves received by a TV antenna

Since we have climbed so far away, it is necessary to at least talk about the basics, because how could it be otherwise!? Radio waves of television channels analog signal distributed in the range of meter (MV) and decimeter shafts (UHF).
In essence, this is the same thing, except that MV and UHF waves propagate at different radio wave frequencies. Meter shafts are from channels 1 to 21, and UHF from channels 21 to 40. It is important to note here that, depending on the wavelength, it will be necessary to use an appropriate antenna for VHF or UHF shafts. It is also necessary to say that antennas are available for both indoor and outdoor use. Let's consider one and the other option.

Do-it-yourself indoor TV antennas (MV and UHF)

MV indoor antenna

The strength of magnetic waves indoors is much less than outside. Therefore, it makes sense to use indoor antennas only in the immediate vicinity of the television center. So the simplest indoor antenna can be made from an electric wire or any other insulated conductor. An insulator is installed in the center of the antenna. Two guides are attached to it using fasteners (bolt - nut). The ends of the conductors are stretched so that they are even, like strings or rods.

The total length of the conductors of the two antenna frames is taken according to the wavelength and the received channel. These can be taken from the table.

If you select the length of the antenna leads, according to what you are viewing television channel, then it will be much more effective than beer cans.
Next we will present another option for an indoor TV antenna that you can make yourself. This is a UHF antenna. Despite the fact that UHF channels are practically not used, broadcasting is still sometimes carried out somewhere. This means that we cannot ignore this topic either. Here is an example of a UHF antenna.

UHF indoor antenna

The mounting wire used, referred to as KPTA-1, serves to increase the antenna's noise immunity. To do this, as you can see, at a distance of 140 mm from the edge of the cable, the insulation was stripped to the screen and this mounting wire - a loop - was soldered. You can use another wire with a cross section of 0.35 mm.
The frequency of received radio waves from this antenna will be from 470 to 630 MHz, that is, UHF waves.
All antenna elements are mounted on a stand, which is a dielectric.

Do-it-yourself outdoor TV antennas (MV)

Antenna - half-wave linear vibrator

This outdoor antenna designed to receive television waves near the city 20-30 km. In fact, this is an analogue of the simplest indoor antenna, which we already talked about a little earlier, except that it is adapted for the street.
So, as we have already learned, the antenna must have certain dimensions, which will affect the reception of television radio waves. The dimensions will depend on which channel you are going to watch. All dimensions for the antenna can be found in the table.

Rice. 1. Antenna - half-wave linear vibrator (Imagines a simple television antenna)

The input impedance of the linear vibrator (antenna) is 73 Ohms. The bandwidth of a linear vibrator depends on the outer diameter of its tubes and increases with increasing final diameter.
You should not choose a D greater than 30 mm, since with its further increase the image quality does not noticeably improve, and the weight and dimensions of the antenna increase.
In table 1 shows the dimensions of the linear vibrator elements. The gap A between the ends of the tubes is equal to 50-70 mm.

The antenna is connected to a TV with an unbalanced 75-ohm input using a coaxial cable (RK-75-4-15, RK-75-9-12, etc.) The cable is connected to the antenna through a special balun (see Fig. 2 ).

The required dimensions of elements of matching structures are selected according to table. 2.

The antenna is made of steel, aluminum or brass tubes and metal strips. To attach antenna tubes to a metal or wooden mast, porcelain insulators and textolite are used.
The antenna - a half-wave vibrator is used in conditions of close enrollment, we have already talked about this. (20-30 km). This antenna option, of course, is a lot more labor-intensive than indoor antenna, but its effectiveness will be much higher. To receive television broadcasts far from the city, or rather from the transmitter, a “wave channel” antenna is used.

Do-it-yourself "wave channel" antenna for MV and UHF - calculation and diagram

On long distances from the transmitter, that is, the television center, it is about 40-90 km, antennas of the “wave channel” type are used. Such antennas have very good gain, but require strict directionality. If you use such an antenna in populated areas, this will reduce interference from adjacent sources, thereby improving the image.
The antenna “wave channel” in its structure consists of an active loop and linear vibrator. We talked about the linear vibrator in the previous paragraphs. The size of the antenna is selected based on the consideration of signal amplification; the farther it is, the more complex the antenna will be. Also, the number of directors can improve the receiving properties of the antenna by changing its sensitivity to the direction of the transmitter.
however, a large increase in the number of directors leads to a decrease in bandwidth. Here you need to find " golden mean" So on MV channels, 3, 5 and 7 element antennas are used.

The geometric dimensions of such antennas of the “wave channel” image are given in the table. At the same time, for channels 1-5, tubes measuring 18 mm are used in the design, and for channels 6-12, 12 mm.

But for UHF shafts a 16 element antenna is used. The diameter of the tubes is 6-10 mm, and for the boom 14-16 mm.

For her, the dimensions are also shown in the table.

After the antenna is ready, you will need to extend the television, antenna cable from it to the TV. About this in the article “Connecting a TV to an antenna cable through a plug.”

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Despite the rapid development of satellite and cable television, reception of terrestrial television broadcasting is still 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 larger number 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 on-air television broadcasting.

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.

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 framework loop antenna narrow range. 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.

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 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 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.
• The 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 the classic scheme for the UHF range, which, because of its shape, is called “Figure Eight” or “Zigzag”.

Design dimensions:

• outer sides of the diamond (A) – 140 mm;
• inner 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 “digits” (Fig. 4). But, if you need to receive other channels in the UHF range, then it is better to stick with “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.

Digital technologies are already sweeping the country, and many are trying to buy TVs that support this format. But if this is not possible, there is another way out - making the antenna yourself. With a little theoretical and practical training, almost anyone can do this.

How to make it yourself dvb - antenna

Digital technologies involve the transmission of images and sound through digital video encodings. It differs from analog equipment in that interference practically does not interfere with the signal, so it arrives at the receiver device with minimal losses.

Today there are already 20 channels of this type. To be able to connect to it, it is not necessary to have special equipment. IN in this case it's about signal reception high quality, for which it will be enough to have a television cable. It is also called coaxial.

For acceptance digital signal You need a decimeter antenna. It’s very easy to do it yourself – you only need an antenna cable. But the main thing is not to make mistakes in the calculations. The procedure is as follows:

1. Take a 30 cm antenna cable and connectors (male/female and F-connector).
2. Prepare wire cutters, a tape measure (at worst, a ruler), a knife and a calculator.
3. Next you will need a computer with an Internet connection. On the website digital television find a dvb channel coverage map, determine which one is closest to your city. There is a search form there.
4. Find a station, find out the detailed frequencies on which it operates.
5. Several channels and frequencies for them may be indicated there. The antenna length is calculated by dividing 7500 by the frequency. For example, if the channel frequency is 754 MHz, the result is 7500:754=9.94. Thus, it turns out that homemade dvb antenna should be about 10 cm long. If there are several stations, the average length is determined.
   
6. You need to attach the F-connector to the end of the antenna wire yourself. It's easy - the cable is stripped and the connector is screwed on top. It is necessary that there is a central wire in the middle, and the foil with the wires is at the attachment point.
   
7. Then move a few centimeters away from the connector, then measure another 10 and cut off what is unnecessary.
   
8. The plastic insulation and “screen” (wires with foil) are removed from the remaining cable, and the antenna is ready. Now the question is connecting it.
   

There is another manufacturing method, which is also simple and requires a minimum of available materials: a board approximately 550x70 mm, self-tapping screws, copper wire (40 cm in length, central core 4 mm in diameter). A blank is made from wood. 8 wires, each 375 mm long, stripped in the middle by approximately 30 mm, thus ensuring good conditions for signal reception. Then you need to cut two wires 220 mm long, and clean the joints according to the size of the board. The remaining wires are bent in a “V” shape.

A special plug connects the antenna and cable (the plug can be purchased separately). The wire is secured to the plug with a tabletop soldering iron. The homemade antenna is ready.

The third method will require:

A small cut is made in the cable sheath, 10 cm from the edge, twist the covering “foil”, cutting off the middle layer by 10 mm.

At the opposite end, install a plug to connect to the TV. A cable is attached to one of the cans, the middle of the wire is screwed to the second, and the best method is soldering; tape is unreliable.

Fix the cans in a straight line on the trempel at a distance of approximately 7-8 cm. Now the device needs to be fixed in the place where the television signal is most clearly received. True, such a device will not be able to pick up many channels, maximum 10.

Feature and dvb connections -antennas

The difficulty may be to find a point in the apartment where the digital television signal would be best received.
Then sometimes problems arise with inserting the antenna into the set-top box or TV. Options - for example, first insert an extension cord into the console, and then insert the cable into it. At the same time, it should not disturb anyone; ideally, it is generally better to hide it somehow.

Self-made structures of this kind, apparently, do not take much time. So for about 100-400 rubles you can build a digital television device with your own hands dvb standard. According to reviews, it works even better than various expensive telescopic devices. True, only for digital TV of one frequency. Not suitable for analog. A high-quality image can be obtained provided that a powerful transmitting station is located no further than 30 km. True, sometimes the distance is reduced even to the range of 5-10 km.

Features of dvb reception

There are also homemade ways to strengthen the signal, especially if the terrain or a large distance from the transmitter (50-100 km) does not allow you to get good digital TV reception. For high altitude external antenna You will need to install a board, and any two-transistor board with a low or medium gain will do. Powerful amplifiers in this case are not required, since the signal is quite distorted.