The president's first multiplex to implement the program in the country is in full swing. Implementation shouldered FSUE RTRS. The company was founded in 2001 to raise the missing at that time the Russian digital TV. This is the only official developer, transforming the country into a figure in terms of the introduction of compulsory mass free TV and radio channels. It is not surprising that ordinary people are concerned about how to create an indoor antenna: willing to gather in their own home.
Digital broadcasting and digital indoor antenna
Do not get tired of repeating that the indoor antenna - just a piece of iron. Accessory does not matter which signal to accept: analog or digital. The leading factor was the polarization, which determines the organization of air waves in space. It shows the behavior of the electric field vector (for magnetic not pay attention as small amplitude of the electric bill and repeats) in the space. The electromagnetic wave process variable. Changing the electric field generates a response from the magnetic field. Constants spread in the environment can not.
So polarization and describes the change in the space of the electric field vector. If changes in the same plane, increases and decreases, then we are talking about linear law. Often it is more convenient that the electric field vector rotates, it has circular polarization. Often that spinning field and is changed: horizontally longer vector vertically less. In this case, observe the elliptical polarization, a special case is the circular (the vector is the same horizontally and vertically). This is a pretty simplistic concept, but make clear the important thing: field organization in the space does not depend on the nature of the signal. Digital or analog, is not important.
When people talk DVB-T, DVB-S, GPS, GSM, do not be afraid. Polarization is of various kinds:
- circular:
- Left.
- Right.
- linear:
- Vertical.
- Horizontal.
Elliptical almost does not apply. And, speaking of standards, exotic methods of modulation and coding, you know, in addition to the above, is not given. Moreover, the circular polarization is used mainly satellites is received purchase-converters, receivers are not constructed by hand because of the complexity. When you need to understand how to make the indoor antenna, the only question polarization vertical or horizontal? You see - how simple!
There are two things that are secondary. First, it is the frequency dependent antenna from its size, consistent with the wavelength. For example, 1800 MHz for the antenna exactly twice less than 900 MHz. Similarly transpose any design. Of course, this is somewhat arbitrary interpretation, but it works in many cases. You will find that a lot of designs, most consist of elementary components. When it is required to cover a large range, multiple antennas are hung on the same mast and are coordinated as necessary. Here came the second time (except frequency).
Secondly, antenna coordinated. For television standard adopted by the wave resistance of the cable 75 Ohm, and for WiFi - 50 ohms. If you do not follow the dogmas of the signal begins to be lost due to reflections. Represented as a journey, while the width is the same, transportation rides boldly, but it is necessary to narrow the band, formed mash.
Thus behaves power line, but does not stop, and begins to "go" in the reverse direction. Moreover reflected repeatedly inducing interference, deteriorating the reception quality. Process describes reflections standing wave ratio (VSWR), ideally equal to one, and is measured by a special device - SWR meter. Professionals are available and other methods, but to implement them need a high-frequency voltmeters, and generators. Sense compiling chain of resistors and the antenna followed by passage of vibrations and adjustable resistance for equality (and use the bridge circuits to improve accuracy result).
As catch indoor antenna first multiplex
When the rumors about the first multiplex immediately found willing to catch. We are talking about complex antennas for a wide range: in this case do not need bells and whistles. The word is taken from the digital multiplexing equipment, it means merging the multiple channels into a single. Here and in the TV room antenna catches numerous programs transmitted on the same frequency. This means that the antenna dimensions are chosen only once, but constantly have to adjust. But in the regions of the first multiplex is transmitted at different frequencies.
This means that the antenna is constructed for a particular region may not work in a nearby town. There are also areas where the frequency is the same. This is bad for transport after moving along the route, the television set will lose broadcasting. The polarization of the first multiplex horizontal. This is a typical solution for television broadcasting. Radio is transmitted on the vertical polarization. This is done to avoid interference. One broadcast will not prevent the second.
Homemade indoor antenna has to be done for the horizontal polarization. Let's see how to implement in practice, and the situation is clarified with a frequency dependent on the size of it. Rtrs.rf offer to visit a website where placed contacts section. This table shows the regions of coverage and phones the next broadcast centers. Even e-mail addresses are available. It is clear that the contact with the company carrying out the digitization of the Russian Federation, we can find out for sure, the frequencies used. You can ask questions and there at will.
Now determined frequency, and indoor antenna is calculated. Several designs, the advantage is that the fans easy to implement in minutes. Assume for definiteness that the frequency of 650 MHz (channel table can be found on Wikipedia, which presents the frequency of sound and images).
Calculate wavelength by school formula: L = c / f = 299792458/650000000 = 46.12 cm
Let us find a quarter of this value is obtained 11.53 cm. This length of a quarter-wave monopole serving receiver. For manufacturing we clean piece of coaxial cable with a characteristic impedance of 75 ohms at said length portion of the screen, the central insulation core do not touch. Cut the cable 5 cm below the treated area border wire and bends at an angle of 90 degrees. Fasten the TV connector sticks to the home plasma TV or a digital set-top box. Cable, cleaned area should be horizontal. This means that the self-made indoor antenna configured for horizontal linear polarization. Rotate vertically and catch catch the radio on the same frequency.
As you can see, an indoor antenna the device is actually simple. But the design is devoid of a preferred direction. It needs to turn the broadcasting station side. The room beam come from any direction, the essence of success - an experiment; Spin the antenna from side to side. Much better results in the balcony achieve using antenna wave channel, already discussed in detail with an example structure for different frequencies. Now let's say that in this case is suitable and biquadratic antenna, a special case of the frame. Judges proposed for television in 1961 Harchenko. This is a simple indoor antenna, manufacture of copper wire takes a few minutes. Orient the product should be upright. Go to the overview of the antenna for modems with their own hands, to see examples of similar structures calculations. Examples are given of the details and choice of materials. The difference is that WiFi and 3G polarization is vertical, so the orientation of the "eight" horizontal.
Led, not all kinds of indoor antennas. The turnover includes, for example, log-periodic. It seems unnecessary to use similar designs, as there are simpler. There are indoor antennas at the sites that look like plastic squares. Copy like in this section. Even drawings resulted. Scale the product according to the frequency. We hope that now the production of indoor antenna with their own hands will not cause difficulties to readers.
