Today’s market offers a wide range of antennas of various types and installation methods, ranging from inexpensive to advanced multifunctional devices. But many consumers are not ready to overpay for a factory product when it is possible to assemble an antenna with their own hands.
Fortunately, the procedure is not as complicated as it might seem at first glance. In addition, you can make a really working device from almost anything. In addition to the assembly, we will consider the main types of equipment, the rules for calculating critical parameters, as well as the correct location of the antenna with the connection. All this will allow you to create a device for some specific conditions.
Conventional TV solutions are bipolar equipment capable of both emitting and receiving signals in a selected frequency range. This segment is represented by models of two main types.
- VHF / MV. The device operates in the meter range. The antenna receives terrestrial TV waves at a frequency of 1 to 300 MHz.
- UHF/UHF. The equipment is designed to work with a decimeter signal in the range from 0.3 to 3 GHz.
Modern terrestrial TV of the DVB standard is broadcast on UHF frequencies. In this case, the format can be classic (DVBT2) or satellite (DVBC2). In the first case, we have terrestrial repeaters broadcasting at frequencies from 314 to 898 MHz, and in the second case, equipment in the ultra-high range from 1 GHz.
Based on this, the following picture emerges: a conventional antenna designed for digital TV has wavelength limits. That is, before you independently assemble the device, it is necessary to calculate critical parameters.
If there are several TVs in your house, then you should learn how to connect 2-3 TV receivers to one antenna.
Why you need to calculate the antenna
Taking into account the tasks that the antenna must perform, it is possible to assemble an all-wave or a device operating in a particular range. And the difference between them is very significant. Universal antennas noticeably worse receive attenuated signals, especially those that are jammed by the background of more powerful radiation. Devices operating in the same range are not so picky about the quality of the waves.
The task is further complicated by the fact that it is very difficult, and sometimes simply impossible, to check the quality of the received signal after assembly. In the case of an analog antenna, everything is simple: albeit with interference, it will catch even the faintest echoes of the repeater. Whereas digital TV requires a stable and clear signal, otherwise there will be no image at all, not even noise. And after assembling the equipment, it is not clear what the problem is: in the antenna, receiver or cable.
Modern smart TVs have functionality that shows the quality current digital signal level, which greatly facilitates the choice of the format of the future antenna, as well as its installation. The rest of the devices are deprived of such capabilities. Therefore, it is so important to correctly carry out the calculations, thereby eliminating problems with the antenna.
Today’s digital broadcasting is organized on different frequency bands and from different multiplexes. The wavelength is also different. In order for the antenna to receive and be able to tune in to a good signal, the emitted waves must be adjusted as close as possible to the active area of the station.
- We calculate the wavelength T2 for each multiplex.
- We denote the sinusoid with the maximum length.
- We calculate the half-length of the cross section of the optimal wave.
Let’s analyze examples of calculations for residents of Moscow and the Moscow region.
There are three digital television multiplexes in the capital:
- 1 package — 546 MHz;
- 2 package — 498 MHz;
- 3 package — 578 MHz.
To calculate the wavelength, it is necessary to adopt a simple formula — L \u003d 300 / F. The letter F indicates the frequency in MHz. That is, we divide 300 by 546, we get 0.55 meters, etc. From the calculations performed, it can be seen that each packet sends waves of the following wavelength:
- L1 = 0.55 m;
- L2 = 0.60 m;
- L3 = 0.52 m.
The multiplex of the second station has a sinusoid with a maximum length, which means that it will need to be used in further calculations. It remains to find out the value of the active area of the future antenna. The wave has the shape of a sinusoid, so its cross section will be half the length and a quarter of the half-length. We substitute the data: 0.6 divided by 4 and we get 0.15 m. That is, 15 cm for digital TV.
Antenna connection and placement
After carrying out the calculations, it is necessary to choose a place to place the antenna and how to connect it. Both options are closely related and may conflict. To begin with, it is worth deciding on the placement: the device will work at home or on the street.
In the latter case, problems with reception are slightly less. outdoor antenna can be installed, for example, on the roof, where walls and other buildings do not interfere with the signal from the repeater. But this is a double-edged sword. The fact is that the quality of broadcasting is affected by the length of the cable, and for outdoor equipment this parameter will be noticeably higher than for home equipment.
As a result, the signal to the TV will reach scattered. The longer the cable, the more noise. Therefore, a compromise will have to be found here. If the building is dense enough, or the station is located at a considerable distance, then in any case the antenna will have to be taken out into the street. With a strong signal from the repeater and the absence of obstacles, it is quite possible to get by with an indoor device.
Advice! There are no clear instructions about the installation of antennas. Each specific area requires a unique placement of equipment. It is best to pay attention to neighboring houses. If they are full of street antennas, then the format of the future device is quite obvious.
When accurate information is needed, it is worth adopting specialized equipment. On sale you can find devices for measuring the quality of the broadcast signal. The main thing is that the device supports the digital format DVD-T and DVB-T2. This technique has the function of a spectrum analyzer, which negates errors in the installation of the antenna.
We make antennas with our own hands
So, having calculated the parameters and determined the installation location of the antenna, you can begin to manufacture the structure.
From coaxial cable
The simplest design for receiving UHF can be done in a short time with your own hands from improvised materials. All you need is a coaxial cable and a piece of plywood of the right size.
Now all this needs to be collected:
- prepare a piece of coaxial cable (PK75) 530 mm long (a ring will be made from it);
- also cut another piece of cable 175 mm long — this will be a loop;
- make a ring (1), solder a loop (2) to it and a cable (3) that connects to the TV;
- fix it all on a plywood sheet and direct the TV signal receiver made towards the TV tower.
If your TV receiver does not pick up a signal using such an antenna, try making a more complex device.
in the shape of a figure eight
A do-it-yourself UHF home antenna can be made from wire in the form of the number 8. This option is called the Kharchenko antenna. To make the receiver, you can use copper or aluminum wire with a diameter of 3 to 5 mm, as well as a PK75 cable. During the manufacturing process, you will also need glue gun.
- Using wire cutters, cut 2 pieces of wire 56 cm each.
- At the ends of each segment, make a loop, which should take 1 cm.
- Bend the wire squares and connect the loops. Solder the cable to the squares as shown. The central core is soldered to one square, and the braid to the other. The distance between the elements should be 2 cm. The entire structure can be fixed in the cap from under the 20 liter water bottle, filled with glue.
Such a UHF receiver can be placed anywhere, and it does not require an amplifier. Unless, an amplifier may be needed if the device is outdoor, and the cable length is significant. In this case, to compensate for signal loss, you will need to install it.
From a metal-plastic pipe
A do-it-yourself television antenna can also be made from an ordinary metal-plastic pipe. This will result in a device for receiving UHF with a possible range from 480 MHz to 1000 MHz. This “model” uses a pipe with a diameter of 16 mm and a cable — 5.5 m. The ring will require 55 cm of pipe, and the rack — 14 cm, which is equal to a quarter of a wavelength. This serves to better match the outer sheath of the cable and reduces high frequency currents.
The cable outlet in this design is made through a hole in the pipe. The cable braid should be attached with a clamp to the stripped part of the pipe. The central core of the cable is attached to the ring (you can use a screw with a washer and nut). Such a homemade product works well as a room antenna in apartments with reinforced concrete walls that do not transmit the television wave well. Thanks to the extended cable, you can take it out to the balcony or put it on the windowsill — the reception quality will only improve.
Another UHF antenna design is assembled in the form of a frame. It will be made from aluminum plates (bands).
- First you need to assemble a frame from aluminum strips. They are fastened with an overlap, using bolts and nuts. It is recommended to paint over the attachment points to prevent corrosion.
- The cable should be soldered at points A and B, as shown in the figure.
- Further, the square assembled in this way is attached to the mast, on which it is already fixed reflector (reflector). As a reflector, you can use a reflector from an old Polish antenna or use a plaster mesh for this.
- For better reception, install an amplifier on a mast and connect a coaxial cable to it (respectively, connect the frame to the amplifier).
From beer cans
An antenna made of beer cans can receive both decimeter and meter wavelengths.. To make such an original CHNA, you will need 2 cans (0.5 l or 0.75) of beer or another drink. But before you make a television antenna, you need to consider some material requirements. Namely, it is recommended to purchase a high-quality television cable with a resistance of 1 meter 75 ohms. How to choose the right cable? Pay attention to the fact that the central core is strong, and the braid is double and solid.
It will also be necessary to prepare the usual wooden trempela couple of self-tapping screws, electrical tape or adhesive tape and, if possible, a soldering iron with tin.
- To make a homemade antenna, you first need to prepare the cable. To do this, measure 10 cm from its end and make an incision. Then peel off the insulation in a small area to get to the insulating screen, which must be twisted in one turn.
- Then, at the same end of the wire, strip the insulation from the inner copper core.
- At the other end of the cable, a regular plug is attached, which will connect to the TV receiver.
- The next step is to attach contacts to banks. We attach a twisted screen to one bank using a self-tapping screw, and to the other — a copper core of the cable.
- After connecting the wires to the signal receiver, it needs to be fixed to something. You can use a regular wooden plank, mop, etc. In this case, a trempel is used (it is easy to hang it in the right place). To fix the cans, tape or tape is used. When securing containers, it is important to observe one rule: they must be on the same axis (on the same line), otherwise the signal reception will be poor. The distance between the banks is recommended to be 75 mm, but you can experiment. It is better to have such a design near the window.
For clarity of the whole process, you can watch the video:
Thus, do-it-yourself antennas will help you save money on their purchase, and in some cases get out of a situation where there is a TV, but the standard antenna is out of order, or it is not there at all. Moreover, the quality of receiving homemade products is not worse than factory counterparts. If you do not want to make the device yourself, then you will need information about which antenna is better to buy in a store.