Antenna for digital TV do-it-yourself

Analogue broadcasting, used previously, since 2009 completely discontinued. Changing the format to digital created the need to use an appropriate receiving device. Digital TV broadcasting is conducted in the UHF range, which is capable of accommodating multiple channels, possessing compactness and high signal quality. The increased level of transmission reduced the cost of equipment maintenance, made it more resistant to interference, although not all problems were solved completely. In rural areas, signal reception is almost impossible, and in a big city it is complicated due to the ability of reinforced concrete structures of multi-storey buildings to screen the signal. For confident reception it is quite possible to make an antenna for digital TV with your own hands, since its cost in the store is quite high.

The principle of operation of a digital antenna

Digitalsecond signal differs from analogue that conveys not the wave itself, and information about it .That is, it consists of a continuous stream of “coordinates” of the points of a specific sinusoidal graphic transmitted by ordinary analog devices. This makes it possible to significantly reduce interference and improve the quality of signal transmission, since the failure in transmitting information does not cause major problems and is quietly corrected when decoding the signal in the receiver. The rest of the transmission technology remains the same - electromagnetic oscillations are emitted from the transmitter into the space, they are received by antennas in the line of sight, on the circuits of which there is a small voltage transmitted to the decoder of the TV and turning into image and sound.

For receiving UHF waves, a small antenna size is required, which distinguishes the devices from the previously used huge antennas that filled the rooftops of houses. The dimensions of digital antennas are quite compact, so they can be freely placed in an apartment, on a balcony or otherwise, convenient for the owner and providing a high-quality reception place. The homemade antenna has a simple design and is quite accessible for production to people without special training, possessing only basic knowledge.

Making a loop antenna with your own hands

A round antenna for digital TV has the highest input impedance

A loop antenna is one of the easiest options. In this case, the resistance to interference from such a device is very high, because the design combines a receiving antenna and interference filter. The name "frame" refers to a specific configuration - it is a closed loop in the form of a round or rectangular frame. Made from copper wire. Also, as an option, you can use a piece of antenna cable( RG6), released from vinyl insulation.

Calculation

To calculate the loop antenna, all that is required is to determine the length of the wire from which the frame is .The formula for the calculation is as follows:

LR = 300 / f,

where LR is the length of the wire in the loop,

f is the wave coefficient, which is the arithmetic average between the values ​​of the boundaries of the wave range. For example, if the broadcast is in the range of 568-720 MHz, then f = 568 + 720/2 = 644.

You can find out the necessary ranges on the websites of transmission companies or from other sources - this information is freely distributed. For the calculation used starting and ending frequencies. If the end is not, then the value of f is taken equal to the initial frequency.

Some experts give another version of the formula in which the side of a square frame is equal to 0.254 of the wavelength( or f).That is, the value obtained by calculating the first formula should be increased by 1.5%.The difference is insignificant, but in some cases it is important.

Required tools and materials

For the manufacture of the antenna will need:

• Passatizhi;
• Ruler;
• Soldering iron;
• Stationery knife for stripping( if an antenna cable is used).

Only the most basic tools are listed, depending on the skills and capabilities of the user, other tools that are more suitable for any purpose can be used.

.

Manufacturing Instructions. Making a loop antenna is easy. You will need to do the following:

• Cut a piece of wire of the desired length. Experienced users are advised to first cut the piece a little longer than the calculation requires, in order to be able to more accurately adjust the length when shaping the antenna configuration.
• Give the antenna the desired shape. If a round loop is used, it is necessary to make a circle as even as possible; for a square frame, the length of the sides should be precisely maintained.
• The ends of the frame are connected to the antenna wire from the TV: one end - to the braid, the other - to the central core. To perform this task, a soldering iron or mounting block with terminal clamps is required.
• It remains to install the device in the best place to receive and adjust the position.

How to make an antenna Kharchenko

Such an antenna can be made by hand for receiving Wi-Fi

The design was proposed by KPKharchenko in 1961.The main task is the reception of television programs, but practice has shown the high suitability and versatility of the invention. Kharchenko's external antenna has the shape of a figure eight with an open middle. It consists of two squares, and the connection with the antenna wire is made at mid-points. Thus, we have a closed coil of thick copper wire, which has a specific shape. The difference from the frame design is precisely in a more complex configuration, which allows to obtain a stable and confident signal reception, noise immunity and reliability of the .Its peculiarity is its broadband and the ability to receive both television and radio signals. It all depends on the location of the antenna - vertical gives a reception of the television signal, horizontal - radio.

Eight form is not the only possible option, you can increase the number of generated squares. Also known options with the formation of circles, triangles, etc. Eight is used because of ease of manufacture and configuration, as well as the absence of interference.

Calculation

Independent calculation of the Kharchenko antenna is not difficult, but includes determining the set of values. It will be necessary to calculate the length of the side of the square, the size of the reflector( reflector), the total length of the eight from the top to the bottom point, the size of the gap between the reflector and the antenna, etc. Therefore, the most simple and reliable solution will be to use an online calculator, which are many in the network. For a more accurate result, you can try to count on several services and compare data.

Required tools and materials

To assemble the Kharchenko antenna you will need:

• Thick copper wire with a cross section of about 4 mm2;
• Aluminum plate for reflector( reflector).In case of its absence, a metal grid( grid) can be used as a reflector;
• Pliers, hammer, screwdriver;
• Electric drill with a set of drills;
• Soldering iron terminal block;
• Metal pipe or wooden long bars for the manufacture of a support structure( mast).

There are plenty of design options for which you can use various accessories. If necessary, they are involved in working order.

.

• Manufacturing Instructions Based on the calculated data, an eight is made.
• The compound at the midpoint is soldered, the second point is subjected to tinning for the subsequent connection of power.
• In the reflector plate, holes are drilled into which bosses are mounted for mounting the antenna.
• It is fixed on the support bosses, the wire is soldered to the central points.
• Reflector plate is attached to the mast. Screws or clamps are used for this, if it is made of a metal pipe.
• The mast with the antenna is installed in a designated place.
• Connects to a TV, adjusts the optimum position.

Other options

A variant of Sotnikov's antenna design of three squares

The options considered are not the only possible ones. There are many designs of antennas for receiving a television signal.

We can distinguish the following:

• Three-element wave channel. It is a rather complex structure of a horizontal bar, on which two transverse strips and a T-shaped frame are installed. A variant of this design is a four-element wave channel containing three crossbars and one T-shaped structure.
• Double square( Sotnikova antenna). Has a gain factor of 10–13 dB, consists of two square frames arranged in parallel and interconnected by a crossbar. A variant of the design is a triple square, the authorship of which belongs to the same Sotnikov. Amplifying capacity is higher - in the region of 14–15 dB.
• Turkina aerial. The gain that such a design possesses is more than 15 dB.It represents six rings of different diameter, fixed on a horizontal dielectric support rod. The device requires a rather careful calculation of the diameter of the rings and the distance between them.

Video: How to make an antenna for digital TV with your own handsThe need to use your own antenna due to a large amount of interference or distance from the repeater. In the absence of the possibility of acquiring a factory-made sample, which is quite expensive and not always commercially available, it is quite possible to make an improvised device, since this is not particularly difficult.

Interesting: