GTC Antenna

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When installing and configuring the receiving antenna on a geostationary satellite – the repeater, it is necessary to calculate coordinates. Since each satellite geostationary orbit is always above a certain point on the surface of the Earth, at the direction of the satellite remains unchanged and is determined only by geographical coordinates of the reception and location of the satellite. Trend is characterized by two parameters: elevation angle and azimuth (Fig. 10). Initial data for calculation are the following geographic coordinates: B – latitude reception, in degrees (North or south); L – longitude location of reception, in degrees (east or west); Lsp – longitude of the satellite in degrees. For these calculations are only used geodetic coordinates, with the maximum precision, determine the best coordinates of the point of reception on a topographic map.

Elevation angle (PA) calculated as follows: The suspension and postirovka satellite dish satellite radio visibility condition is a condition: Suspension and postirovka satellite dishes in Otherwise, the satellite will be below the horizon and receive from him will be impossible. Determination of the azimuth is as follows: The suspension and satellite dishes postirovka sign "+" is used when the satellite Located west of the place of reception, and "-" sign if the east. Characteristics of the direction of the satellite antenna orientation method considered in a direction that would watch satellite TV on a satellite called azimuthally elevation, since it is produced by two coordinates: the azimuth and elevation. A distinctive feature of this method of orientation is to inform that the azimuth antenna rotates about an axis located vertically relative to the earth's surface, called the azimuth axis of positioner antenna. Therefore, at any latitude except the point of taking the north and south poles azimuth axis intersects the plane of the equator and, therefore, the plane of the geostationary orbit at an acute angle. This leads to the fact that each satellite, placed in geostationary orbit are consistent for the personal receiving point values of azimuth and elevation direction of the antenna.

If re-adjustment antenna from one satellite to another is necessary to change the direction of the antenna, as in azimuth and in elevation. In Unlike the azimuth-elevation there is a method of orientation of the polar orientation, which enables the re-orientation of the antenna from one satellite to another only in one coordinate. To do this, rotate the antenna azimuth shall not occur around a vertical axis of the azimuth, and more around an axis parallel to the axis of rotation of the earth. Due to the fact that in the direction of the axis of rotation of the earth is the North Star, the More axis is called the polar axis. The design of the GTC is shown in Fig. 9. For the polar orientation is still required that a mechanism of vertical axis and the antenna about this axis, and a mechanism the antenna in elevation. However, these mechanisms are used only once, when installing an antenna. Further re-orientation of the antenna from one satellite to another is done only by turning around the polar axis.

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