Assembling a homemade antenna for digital television, examples of do-it-yourself TV designs

Humanity lives in a digital age. Television is switching to digital transmission of signals. The peculiarity of digital broadcasting is that it is conducted in the decimeter range.

The transmitting stations have a low power of the transmitted encoded signal. Therefore, to receive the signal and display the image on TVs that are far from the station, a receiving digital antenna is required. If you do not know how to make an antenna for TV, then the answer is simple: you can assemble it with your own hands from scrap materials in just one hour.

Receiving antenna types

For reliable signal reception from a TV tower, there are many different television antennas. They differ in shape and range of receiving frequencies.

Antennas can be categorized into several basic types:

• Wave. To receive the wave channel. Consists of a vibrator (active element) and a reflector with a set of passive elements. The whole structure is installed on a common base - an arrow. A reflector is needed to reduce the level of signals that try to enter from behind. The vibrator picks up the main signal coming from the front of the antenna.
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• Traveling wave. Consists of a rod - a collecting line, on which several vibrators are evenly located. All vibrators are active and folded, the accumulated signal goes to the collecting line.
• Framework. They are used when simple antennas are not enough for reliable reception. The name "double square" is widely used. A characteristic feature is undemanding customization.
• Log-periodic. They provide good reception of TV channels in a very different frequency range: from meter waves to decimeter ones. The incoming wave is received by a series of vibrators. Those begin to work, the dimensions of which are close to half the wavelength. The principle of operation is similar to that of several waveforms connected together.
• Lattice. A complex system that consists of identical separate weakly directional antennas, distributed in space in such a way that the phases of the captured signals are the same. Due to this, there is a multiple amplification of the signal.

Currently, the vast majority of television signals are transmitted using digital coding. Broadcasting is carried out in the decimeter range. The format of this transmission is called DVB - T2.

Theoretically, this signal can be received by some old universal antennas, which marketers used, calling them DVB-T. In order to distinguish the new narrow-profile decimeter antennas from the old classic ones, the number "2" was added at the end of the abbreviation.

Basics of digital television

Television transmitters transmit digital signals over relatively short distances. The transmission range does not exceed sixty kilometers and is limited by the line of sight of the emitter from the TV tower.

For these distances, a low power signal is sufficient. But the design of the receiving antennas must meet certain requirements:

• Accuracy in manufacturing. Accuracy of reception must exclude loss of signal strength.
• Should be located along the axis of the traveling electromagnetic wave.
• Mandatory orientation by the type of polarization.
• There must be protection against interference that coincides in frequency. These can be radio transmitters, generators, electric motors.

The digital signal has its own unique feature. He can either be caught or not. He has no middle position.

If the digital signal is one and a half decibels higher than the noise, then its reception is always of high quality. The signal can disappear if the cable is damaged or the phase is distorted in the transmitted section. In this case, even if the signal is strong, the image splits into small squares.

In order to catch decimeter broadcasting, an appropriate antenna is required. According to theory, any antenna will do, but in practice there are nuances.

There are several types of antennas for DMV receptionoffered by manufacturers:

• Room. Capable of receiving a digital signal only up to ten kilometers from the station. At this distance, the signal can be received by an ordinary long nail, directed in the desired direction.
• Raven type. It catches a signal at a distance of up to thirty kilometers. Installed outdoors. It is not necessary to aim at the signal source for normal operation.
• DIPOL 19 / 21-69 type. Confidently picks up a signal up to fifty kilometers. It is installed at an elevation of about ten meters and requires location strictly on the repeater.

It is not difficult to make a do-it-yourself antenna for digital TV.

Assembling antennas at home

bend shapes should be as smooth as possible. Basic phase distortion appear due to dips and emissions of a sharp nature.

Homemade digital antennas are frequency independent. They do not have the best characteristics, but they are easy to assemble and take little time and money to design. Suitable for work in a noise-free air at a short distance to the repeater.

Receiving a signal to beer cans

From ordinary beer cans, you can construct a simple all-wave antenna. Of course, it is inferior to industrial designs and is not always able to provide a stable signal, but it serves its purpose well. This device accepts at least fifteen channels at least.

To assemble this structure, you will need:

• Two beer cans, seven hundred and fifty or one thousand milliliters each.
• Coaxial TV cable (RK75).
• Antenna plug.
• Scotch tape or duct tape.
• Screwdriver.
• Knife.
• Nippers.
• Self-tapping screws for metal.
• Plastic board or tube. This is the future foundation of the design.
• Ruler.
• File.

After rinsing and drying the metal cans, DVB - T2 can begin to assemble the antenna.

Carefully, so as not to deform, pierce through the hole in the upper parts of both cans. A screwdriver is suitable for this procedure. With its help, self-tapping screws are screwed into the prepared holes.

Then take one end of the cable PK75 and at a distance of ten to twelve centimeters with a knife is cleaned from the upper shell. In this case, the copper braid must not be damaged. The braid is twisted into a pigtail. The aluminum screen is removed.

Then the polyethylene shell is cut off by six to seven centimeters and the central core is exposed.

The resulting pigtail and central core are screwed to self-tapping screws. If you have a soldering iron and skills in using it, then it is best to solder parts of the wire to the banks.

Banks are sequentially fixed with adhesive tape along a plywood board or other base that is at hand. The distance between the banks should be seven and a half centimeters.

At the end of the work, a plug is connected to the second end of the cable.

To do this, the end of the cable is stripped and the central core is passed through the hole in one of the halves of the plug. The cable sheath is attached to the plug housing. One half is screwed onto the other and, as a result, we get a plugready to go.

All that remains is to connect it to the antenna input of the TV and place the antenna in the right place where the quality of the received signal will be good.

In the event that the created structure is placed outdoors in the open air, it is necessary to protect the device from moisture and dampness. For these purposes, you can use plastic bottles in which the bottom and necks are cut off. Inside them are the metal parts of the antenna.

The resulting model is easy to "tune" by turning it in space and simply moving around the apartment, balcony or summer cottage.

Zigzag antenna Kharchenko

The engineer K. NS. Kharchenko in 1961. For reception of a digital signal, it perfectly suited and received wide deserved recognition. It is popularly nicknamed the "eight" and the complete assembly looks like two rhombuses, one above the other.

When making an eight you will need:

• Copper wire with a diameter of 3-5 millimeters.
• Coaxial antenna cable 3-5 meters long and 75 Ohm.
• Soldering iron with solder.
• Scotch tape or duct tape.
• Plug.
• Bolts for assembly.
• Base: plywood or plastic sheet.

At the first stage, we assemble the antenna frame. We take a wire 109 centimeters long and bend it in the form of a frame. The frame has the shape of two consecutive rhombuses with sides equal to thirteen and a half centimeters. One centimeter will remain. A loop is made from it, which holds the wire together. The ends of the frame are soldered to each other and thus it turns into a closed loop.

The coaxial cable is then stripped. The cable screen is rolled up into a tight rod and soldered to the wire of the frame in the place where the diamonds converge. The central cable rod is also soldered in the central part of the frame. The core and braid must not touch each other.

The other end of the cable connects to the plug. The plug in the soldering points is preliminarily wiped with alcohol and processed with sandpaper. The mono-core is soldered to the central outlet of the plug, and the twisted braid is soldered to the side.

If the frame will be used outdoors, then the future plywood base can be painted or varnished. The soldering points can be wrapped with tape or electrical tape. But this is not the best option, as the sticky tape can unwind over time. If, before soldering, plastic tubes of a suitable diameter are put on the wire, then at the end of the work the tubes are pulled onto the welded places and reliably protect the frame. After that, the frame is installed on the prepared base.

The digital antenna is assembled by hand and ready for use.

If desired, you can assemble an antenna tuned to a specific wavelength. To do this, you need to calculate the length of the square. This is not difficult: the wavelength of the desired signal is divided by four. As a result, the desired value of the length of the rhombus of the frame is obtained.

The simplest cable antenna

It requires one 75 ohm TV cable. The required cable length is calculated based on the desired digital broadcast frequency. Its value in megahertz is divided by 7500 with the resulting sum rounded.

The resulting value is the desired cable length.

After that, one end of the cable is cleaned of external insulation and inserted into the antenna connector of the TV. A mark is made on the cable from two centimeters after the connector.

It is from this mark that the required cable length is counted. The excess part is pinched off with pliers.

After that, you need to return to the mark on the cable. Only the insulated bar is left at this point and the outer braid is removed. The cleaned part is bent at an angle of ninety degrees.

All is ready. The TV can be tuned in with a new antenna.

Installation safety

For the reliable operation of such antennas, they must be placed above the ground at a level of 7-10 meters. Therefore, during installation, it is necessary to strictly observe safety rules:

• Do not mount the structure in heavy rain or heavy fog.
• It is undesirable to go upstairs alone, especially in ice, cold, snow.
• If it is necessary to climb a wobbly structure or high-altitude work is carried out in dangerous places, then a fixed mounting belt is required.

After proper installation, homemade antennas work no worse than factory antennas with significant budget savings.