Footprint (satellite)

Illumination zone or spot beam footprint ( often written as footprint ) is a term used in satellite technology. This refers to the figure of the reception area of a satellite signal on a map. On some footprints, the signal strength or that the resulting calculated the required antenna size in different areas of the footprint is represented visually.

Footprint map

Footprint maps are most frequently used in geostationary satellites and are used for fast visualization, whether it is possible to receive signals of the targeted satellite in a region at all and if the signal strength is specified, which antenna diameter this is necessary. So you can based on the footprints of Astra 1M - broadcasting satellites (see section links ) recognize that the signal on the "Wide Beam" of the satellite Astra 1M is now broadcast in the Middle East. The "European Beam", however, is limited to Europe.

A footprint map, however, can only represent the possibility in principle of the reception. Reasons that the reception is not possible, among other things, to small satellite dishes ( the signal strength is not enough for the reception with the standing to available antenna size ) or landscape damage at ( located in the way houses or trees can degrade the reception situation or by reflections facades otherwise modify ).

Ausleuchtbares area

Due to the spherical shape of the earth and the beam geometry can be up to almost half the earth's surface irradiate a very distant satellite; a satellite in geosynchronous orbit can be irradiated with a 'global beam " is about 42 % of the earth's surface. Such footprints are found but only in the C-band. The lower the orbit, the smaller is the maximum irradiatable area. A geostationary satellite with an altitude of 36,000 km above the earth ( the radius of the orbit is thus 42,300 km = 36,000 km 6300 km for half the diameter of Earth ) is just visible up to a latitude of 82 ° on the horizon, at a altitude of 1000 km, only at 30 ° latitude. At an elevation of 10 ° reduces the width to 70 ° or 20 °. The derivation of this relationship is found in Article sight.