Yak of a vibrata to a suputnikov antennaSatellite “ plate “ in consciousness “ general population “ by right represents all satellite reception system. Of course, actually any television satellite system consists of many parts though the antenna absolutely objectively is nearly its most important detail. And at least, it is difficult not to agree that the antenna - the biggest and noticeable element of reception system.
In the previous numbers on the shy magazine we already told how to choose a satellite receiver (T / With No. 12, 1997 of) and the converter (T / With No. 1, 1998 of) . Today we will talk about satellite antennas, the right choice of the antenna in many respects defines technical capabilities of your satellite reception system in general.
Before saying about how to choose the satellite antenna, it is necessary to define: as a part of what reception satellite system it intends for work. That is, choosing the satellite antenna (as however and other components of reception system), you, for a start, need to answer yourself several questions:
In what cover zone of satellites you live that is what satellites you in principle can accept?
What channels interest you and what, proceeding from it, you want to watch the satellite? whether
Is available an opportunity to arrange the antenna so that local “ objects “ did not close the direction on the satellite? whether
you Want to watch one or several satellites?
What financial means which you want to enclose in it “ " enterprise;?
Will help to answer the first two questions to you in any firm which is engaged in satellite television in your city. If you want to understand everything, perfectly!
Our magazine regularly publishes on the pages coverage maps * for various satellites, and detailed reviews of the satellite channels broadcast from different satellites are located nearly in each number.
the Satellite antenna (a mirror) is intended for focusing on an irradiator of the converter of a parallel bunch of the radio waves radiated by the satellite. The antenna represents part of a paraboloid of rotation as such form provides fine focusing of a parallel bunch of radiation.
Television signals are transmitted from satellites, in Ku ranges (~ 11 GHz) and With (~ 4 GHz), that is the accepted signals have the wavelength of 27 and 75 mm respectively. For this reason any obstacle (dense overcast, snow, a rain) in a way between your antenna and the satellite will weaken a signal and can exclude in general (if this obstacle - trees, buildings etc.) possibility of program reception of satellite television.
Pryamofokusny antenna (prime focus). The visible direction on the satellite coincides with a perpendicular to the plane of a raskryv of the antenna
in principle if you did not forget yet what is a sine, and can find the place where you are on a map, it is possible to define the visible direction on the satellite (an azimuth and a corner of the place), having used a formula 1.
Now it was necessary only to take a compass and to be convinced that in this direction there are no obstacles closing the satellite (trees, the neighboring houses or, for example, a factory pipe).
1 antennas. The size
For a start we will deal with the mirror sizes. Diameter of the antenna depends on power level of the signal accepted from the satellite in your district (which can be determined by a coverage map). Thus diameter of the antenna necessary for program reception from that satellite on which you decided to adjust the antenna will depend on your geographical position. Approximate ratios of power level of the accepted signal and diameter of a mirror necessary for this purpose are given in table 1.