An antenna tracking system tracks a primary antenna to follow a moving signal source, such as a

communication satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...

. A secondary antenna has a greater

beam width The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be defined in many differ ...

than the primary antenna and receives the same tracking signal from the satellite. The primary antenna is tracked according to a predetermined search pattern which causes a variation in the signal

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of amplit ...

depending upon the relative location of the satellite and the antenna position. The signal strength signals from the two antennas are input to a summation function which takes the

difference Difference, The Difference, Differences or Differently may refer to: Music * ''Difference'' (album), by Dreamtale, 2005 * ''Differently'' (album), by Cassie Davis, 2009 ** "Differently" (song), by Cassie Davis, 2009 * ''The Difference'' (al ...

of the two signals. The noise and signal variation component of the two signals is substantially the same and is therefore eliminated from the resulting difference signal. An antenna control unit utilizes the resulting difference signal to select the optimum

signal strength In telecommunications, particularly in radio frequency engineering, signal strength refers to the transmitter power output as received by a reference antenna at a distance from the transmitting antenna. High-powered transmissions, such as those us ...

for the particular step of the search pattern. This system is particularly applicable to

extremely high frequency Extremely high frequency (EHF) is the International Telecommunication Union (ITU) designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz (GHz). It lies between the super high frequency band and the ...

communication channels (86 GHz and above) which are subject to

atmospheric distortion An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...

and

noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference arise ...

. Antenna Tracking Systems can apply to Broadband and Microwave Radio Systems as well for Point-to-Point and Point-to-Multipoint communications.

References

* * * * * * {{reflist Telecommunications equipment Communications satellites Satellite broadcasting

See also

References