If the meter range, even factory wideband antenna characteristics do not give a premium, like his own design - bad job. Otherwise the situation in the DMV. There exits a smaller device size, acceptable characteristics. How does TV antenna, gathered for three multiplexes in Moscow. Characterized considered in applying to the first. Regions! Do not rush to flip through the review, the frequency of the country fall within the range from 470 to 900 MHz, the difference in the specific values.
Digital television in Moscow
In the spring of 2013 in Moscow two multiplexes:
- The first 32-m channel.
- The second on the 24th channel.
The third multiplex yet sits frequencies occupied by analog television. Need antenna, receiving both 9-10 channels in the UHF range. The said conditions are satisfied by wave channel, Udo-Yagi antenna. Tuned to channel 28 and comprises not more than 5 directors. Recall coefficient depends on the number of devices gain plus broadbandness. These qualities are at war! The higher the aimed properties and the antenna gain, the more narrow frequency portion covers the device.
Broadband antenna type wave channel for digital broadcasting
For Moscow, the average frequency of the 28-th channel accounted for 530 MHz. Consider how to design a suitable device. If the gain is not enough, all-wave television antenna personally do not produce. It is better to build two separate devices for the 24 th and 32 th channels, respectively. How do I already told you.
Our antenna will receive a relatively small length. Clearly less than 13 directors, the amount is considered optimal for devices aimed at single channel. In addition, interference from neighboring fall below the designed properties better. For the reasons for receiving two or more channels will need to reduce the directional properties, and expand the operating band. This is achieved by reducing the number of directors to 5. Homemade TV antenna "stretched" for 10 channels, 12 to take permissible, but are extreme in bad quality.
As already noticed readers multiplexes lie just at the edges, increasing the number of directors to 7 is not allowed without reducing the quality of reception. Parabolic antenna for TV Tricolor designed to receive a single frequency from the satellite, visible in the sky. The challenge is different: it is necessary to catch the broadband signal with the unknown azimuth.
Structure homemade antennas for receiving first and second multiplexes Moscow
Production of a television antenna on the views of the author means that the product is able to collect the student. Having the necessary materials, of course. Yagi antenna, eliminating the mast consists of four elements:
- Active vibrator.
We recall that the circuit comprises a television antenna 5 directors. The first item in the list is often assembled from metal, it is wrong. Traverse manufacture of a dielectric material. Sure stubborn try to weld the elements to the steel pipe. We offer first examine the size, to figure out what to collect from the device:
- Reflector length - 28.6 cm.
- The length of the driven element - 22.9 cm.
- The height of the driven element - 5 cm.
- Symmetrical sectional view of the driven element for removing signal - 2 cm.
- Directors length - 21.8 cm.
- The distance from the reflector to the active vibrator - 12.6 cm.
- The distance from the vibrator to the first active Director - 7.4 cm.
- A distance from the first to the second director Director - 13.9 cm.
- The distance between the other directors - 16.8 cm.
It is easy to calculate that traverses the length of the leaves 85 cm. It fits into the dimensions of suburban Spades for shovels. It is permissible to use a segment of the polyethylene pipe. Directors, the reflector and the top of the loop of the driven element on a common height and are parallel. Attach possibly bolts, screws over time shattered. Prompt option fluff thread glue, then is allowed to use self-tapping screws for wood. Inside the loop traverse active vibrator should not be held. We cling element of the upper part to the bottom of the cutting. Similarly, the other elements possess a similar plane.
Before you use the stalk must be cut to length with a margin of at least 7 cm, to mount the last director and reflector. Then process the wood preservative, waterproofing the ground, giving wood resistance to weather. Of course, the compositions are intended for outdoor use. We do not recommend painting the product does not make sense, but it's great complicate the process.
Interesting! Today, the sale is a shrink film. Due to the high cost of not risking to offer cutting spade swift. But in consideration of the method take.
Directors, the reflector and the active vibrator made of copper or aluminum wire. Suit and tube. Preferably copper, as better conductivity, and the length of the elements is not so large to fear heavy weight. If there anticorrosive primer for metal elements bother ready to process the composition of the copper shock oxidized. Tube should be sealed. Take the wire of circular cross section for optimum reception. You may use the cores PVA or similar power cables. Need sealant insulate the ends cut, the material has protected against corrosion.
Fixing of Directors, and the reflector of the driven element to traverse conduct on plastic or steel brackets with an eye. You can put the screws or bolts to the sealant. Mast for TV antenna is assumed steel must stand behind the active vibrator. You can not allow fasteners to the segment traverses between the first director and active vibrator.
Traverse is fixed to the mast better on a steel clamp, one side is welded to the pipe. Stretching from a steel wire attached to the ears. Allowed to drill in the mast for the purposes of these holes:
- diametrically drilled hole for the bolt;
- on both sides of the washers are mounted two extensions;
- 5 cm below a diametrically drilled hole perpendicular to the first;
- on the bolt washers are attached two additional extensions.
Four extensions will be enough to secure a mast. It is much more difficult to fix the roof. Here we offer puncher to punch holes in the concrete, if the apartment building. Not too deep. To keep the tree is much easier to mount. Do not forget under the clamp at the junction of the mast and traverses pour glue or sealant strength. Nice to make a spacer at an angle, but at home have to perform complicated.
Slot TV antenna cable is designed for 75 ohm. Consequently, the need to align the device. Wire with low loss can be bought at the store for a price of 10 rubles per square meter. agree - to provide the best match, a special device called applied. Purchase antenna for TV Delta does not need any procedure designed in a special way, but homemade pass through it in order indispensable.
Coax, sold in a store, unbalanced, our active vibrator exactly symmetrical. With a cable length of 12 meters lowering it does not matter, the loss is not great, but if you pull from the ground floor to the roof, the attenuation should be less, will have to agree on the device. In the simplest case, a balun cable segment 75 ohms and a length of 28-th channel equal to 14.2 cm. Throughout the cable parallel cable to the TV. Connect balun segment:
- He lived planted at the end of the driven element, which fits the signal conductor cable television.
- The screen segment is short-circuited at the specified location.
- On the opposite side to the length of 14.2 cm from the vibrator active outside insulation of the cable television slightly trimmed.
- Screens and balun cable are connected.
- At the same time start up here living.
It turns out that the balancing at both ends of the device's screen and lived short-circuited. The distance from the segment to the television cable 30 - 50 mm. Simply fill in the design on top of the sealant when homemade checked for serviceability. Do not use Chinese glue gun, the composition used does not tolerate moisture. The rain and wind pluck imposed isolation, baring design.
Antenna TV from cans certainly looks good in a TV program, but the long-range reception with it will not be able to provide. For longer trips, reserving the described method. Even being in the country, easily worthy to the normal structure, which does not refuse to accept broadcasting.