At present, the process of transition to the digital format of television broadcasting is underway in our country. Large Russian providers have already re-equipped their facilities, which speaks volumes about the end of the era of analog television. And in order to save money and maximize efficiency from using previously installed home antennas, you should connect a DVB-T receiver to the TV, as a result of which the correct reception of digital signals will be realized.
It is quite obvious that assembling a digital antenna at home, which will significantly save on functional TV equipment, does not require special skills, and improvised means can be used as materials used. To do this, you just need to understand the very principle of operation of the antenna device, provide for the presence of uncomplicated tools and materials, make an elementary calculation and installation, and also connect it.
Among the many design options for digital antennas for DVB-T2, you can opt for the most common model that guarantees high-quality signal reception, which is called the "eight".
The principle of operation of the antenna for digital TV
A TV signal in any format (digital or analog) comes from special emitters located on the tower to the TV antenna. In the case of digital processing of the received signal, it is required to use a sinusoidal device with the highest frequency.
When an electromagnetic wave arrives at the receiving part of the dtv-t2 antenna, the V-voltage is induced in it. Thus, each wave forms a potential difference, marking it with a distinctive sign. The resulting induced voltage in the closed loop of the receiver creates an electric current that will gradually increase. Its transformation into a picture on the monitor and sound in the speakers is done by electronic processing of the TV circuit.
It is important to understand that a conventional indoor antenna is not capable of converting a digital broadcast signal. To do this, you need to use a special decoder (DVB-T receiver) and a decimeter antenna (Turkin's antenna).
Materials used for the manufacture of the antenna "figure eight"
To create a dvb-t2 antenna on your own, you must initially collect the necessary material and tools. Of all the variety of antenna options, it is possible to recommend the version with the "eight", as it is quite reliable in use and easy to assemble.
So, you need to find a copper or aluminum wire, the diameter of which will be from 2 mm to 5 mm, a tube, an angle and a copper or aluminum strip.
As a tool for making the antenna, you will need to use a hammer and a vice to securely attach the material. Not only wire can be used as a material, but also coaxial cable. In addition, you will also need a plug that will connect the antenna to the TV connector. You also need to make an antenna bracket, the type of which will depend on where it will be installed (in a room or outdoors).
The cable must be selected based on its resistance in the range from 50 ohms to 75 ohms. In addition, you should not forget about insulating materials (electrical tape or heat shrink tubing).
Regarding the manufacture of the bracket, it should be understood that when attaching the antenna indoors, it is enough to use, for example, pins, but for the outdoors, the bracket is simply necessary. In this case, you will need a file, a file and a soldering iron.
Not only a spiral antenna, but also a design in the form of a double square can act as an antenna "eight", which will affect the frequency range and the number of channels. Such an antenna arrangement would require the use of copper, aluminum or brass tubes (alternatively with 3-6 mm wire).
Calculation and manufacture of a digital antenna
The connection of the two frames with the upper and lower arrows is the double square. One frame (small) serves as a vibrator, the other (large) as a reflector. The use of the third square (director) is also possible. A wooden beam must be used as a mast (at least one and a half meters).
Point instruction:
- stripping the coaxial cable from both sides;
- provide a 2 cm overlap on the side of the cable that will be attached to the antenna;
- twisting the braid and cable screen into a bundle;
- we got two conductors;
- the plug should be soldered to the second end of the cable; for this it is enough to use 1 cm of the cable length;
- you need to tin and make two more conductors;
- wipe the soldering points with alcohol;
- fix the plastic part of the plug on the wire;
- solder the mono-core to the central entrance of the plug, and the stranded bundle to its side entrance;
- you need to squeeze the grip around the insulation and screw on a plastic tip or fill this place with glue as a sealant.
To configure reception of broadcasting in the digital range, it is not at all necessary to make an accurate calculation of the wavelength, because it is enough to use a broadband design. To do this, you just need to add some elements to the T2 antenna.
To determine the side of the square of the antenna, it is necessary to divide the wavelength of the received signal by four. And in order for the two parts of the component device to be at a certain distance, it is necessary to make the outer sides of the rhombuses slightly longer, and the inner ones shorter. As a ready-made solution on the sides of such a rectangle, the following values can be taken: the inner side will be 13 cm, and the outer side - 14 cm. It is important to understand that the squares should not be connected to each other, and the distance between them makes it possible to roll up the loop to which the coaxial will be attached cable.
Thus, for the manufacture of this design of the antenna device, 1, 12 meters of the material used (wire or tube) will be required. After cutting the required length of material, you need to bend it with pliers and a ruler. An important condition is the angle of each fold, which should be approximately 90 degrees.
With the correct manufacture of the antenna frame, its design will contain the necessary clearance between the two halves. Next, you need to clean the hinges and bend areas to metal using sandpaper with a fine grain, connect the hinges and squeeze them to fix with pliers.
After making the structure itself, you need to start processing the cable. Stripping the wire on both sides should provide a two centimeter headroom at the point of connection to the antenna. Then it is necessary to twist the screen and the braid of the cable into a bundle, and tin the resulting two conductors.
The next step will be to solder the plug to the other end of the cable, in which you need to use similar preparation rules. Having placed the plug in the soldering point, you need to degrease the area with a special solvent or alcohol, clean it with a file or file and put a plastic fragment of the plug on the cord. After that, it is necessary to solder the core to the central entrance, and the braid to the side one. And around the insulation you need to squeeze the grip.
Next, you need to screw on a plastic tip or fill the junction with glue (sealant), which will allow you to strengthen the fixation. During the solidification of the base, you need to quickly assemble the plug, and then remove the protruding excess of glue or sealant.
After making the DVB-T2 antenna frame, you need to connect it to the cable. Since precise binding to a specific channel is not necessary, you can solder the cord in the middle of the structure, which will create a broadband antenna with a large number of received channels. And the second divided and pre-prepared edge of the cable must be soldered again in the middle to the other two sides of the antenna structure.
Connecting a digital antenna
After connecting the tuner, you need to turn on the TV to check the functionality of the antenna device. In the case when it was possible to set up a sufficient number of TV channels, it is necessary to complete the assembly by filling all the soldering points with glue or sealant.
Otherwise (there are few channels or reception with interference), it is necessary to experimentally find the junction of the frame with the coaxial cable, which provides the most optimal reception of the digital signal. If this does not lead to the desired result, then you need to change the cable. In this case, it is better to use a telephone cord as a cable for testing, which is more economical.
Ordinary electrical tape can be used to insulate the solder points between the cable and the antenna frame. However, the most guaranteed protection against external conditions of an aggressive external environment can be the use of heat shrink tubes or sealant. It is this kind of insulation that will ensure the durability and reliability of the structure. For normal operation of the antenna device, you need to make a case for it, which can also be a simple plastic cover.
