problems that may arise in the reception of television signals All cities have areas that are difficult to receive TV signals.
In these cases it is necessary, sometimes, many experiences before coming to get a satisfactory picture.
no doubt that from the professional point of view can solve any problem but sometimes the solution requires a budget as high as the client rejects a certain undisguised suspicion.
All buildings representing a display that greatly attenuates the signal to the homes of lower altitude.
Moreover, wherever there exist a television station limits areas. This area is between 40 and 100 km from the transmitting antenna and get good reception is necessary to comply with best technical conditions required for best performance of an antenna.
For a more powerful transmitter limited area could be between 60 and 120 km, but anyway, this area always exists.
limits areas in the most important factor to consider is height. It is much more important than the type of antenna. The question is which is the minimum height sufficient for a good image. When we have the antenna at a height of 15 meters and still does not satisfy us, we do not know enough lift it metro station, five to twenty meters. There is no other way to find out more testing and these tests cost time, material, personnel, etc.
ANTENNA WHAT SHOULD I INSTALL? .. DO NOT BE FOOLED.
Some people get confused and do not hesitate to buy fashion antenna that offers the market, an antenna that is not adequate to the reality of our country. But it looks pretty and has control, rotor etc. If installed in rural or poor signal realize that it was the right antenna to solve your problem and more material quality is poor.
antenna models are very different models of antennas that are in the trade. These differences due to the need to comply with different qualities for different reception conditions.
1 .- To receive one or more channels
2 .- Frequency of the various channels. You can receive channels 11 and 13 or 3 to 10, very different situations for the proposed antenna more suitable;
3 .- respective powers;
5 .- Obstacles presented by each area to receive one or more channels.
But do not look for the ideal antenna for all cases does not exist.
Much less expected that the larger antenna will be the best. The antenna size bears no relation to the quality but that depends on the frequency you wish to receive. Thus the size of a dipole for channel 2 should be approximately 2.60 meters. As for channel 13 is not greater than 65 cm.
channels 7 to 13 have the advantage of requiring smaller antennas while for channels 2 to 6 antennas have to be much larger and therefore more expensive.
All wire, cable and electrically conductive object antenna ago because currents are induced in them from all electromagnetic fields found in space. You only need a method to collect these induced currents and bring to a receiver.
This would be the difference between a good antenna and a driver either.
So far we have avoided any mathematical formula but as exception included below which gives the length must have a driver for maximum induction of a specific frequency signals.
Speed \u200b\u200bof light = frequency wavelength
This formula gives us the Wavelength of a certain frequency. The ideal length for the antenna is a conductor of length equal to half the wave length of the frequency to be received.
To this dipole antenna is called and it underpins all types of antennas used on television.
Example for channel 2
The picture and sound are 2 completely independent transmissions although air waves are transmitted through the same antenna. the separation of both in frequency is very critical and fundamental part of the conditions that characterize the so-called Television Standards. In American Standard separation between them should be 4.5 Mgs.
For channel 2 we have that the frequency of transmission of video signals is 55.25 MGCs. And the sound is MGCs 59.75. To calculate the antenna
takes an intermediate value between the two frequently. This would be 57 MGCs. And we have:
300,000,000 meters x seconds
wavelength x seconds = 57,000,000 cycles
What gives 5.26 meters. Half of this value is the length you should have a dipole for channel 2 would be 2.63 meters. A 5-element antenna for channel 2 would have a size of 2.63 wide by 5 to 7 meters long. Too big and heavy to be practical.
whose frequencies for channel 13 video and sound are MGCs 211.25. And 215.75 MGCs. Respectively the dipole needs to be of a length of 65 cm.
A 75 cm antenna. It may be suitable for all channels 7 to 13.
An antenna of 1.75 meters. It may be useful for channels 2 to 6
Atte. Alejandro Lillo V. Communications Antenet
htpp: / / aloja.cl/02/antenet.
