Antennas Used In Satellite Communication

Explain with neat diagram the antennas used in satellite communication.

Antennas used in satellite communication.

Satellite borne communications antennas are located very far from their service area on the earth. If a parabolic reflector antenna is used for transmitting a signal the signal from the feed comes out of a dipole or a horn antenna to focus the wave on to the parabola. It means that the. Nearly isotropic antennas can be constructed using multiple small elements and are used as reference antennas for testing other antennas and for field strength measurements and for backup antennas on satellites which work without the satellite being oriented towards a communication station.

These antennas can also be used as electromagnetic field probes in the microwave bands. Uhf communications satellites often use downlink frequencies around 250mhz and uplink frequencies around 310 mhz. The most widely used narrow beam antennas are reflector antennas. Communication antennas used in geostationary satellites are normally reflector antennas to overcome the high loss due to height of geo orbit the receiving and transmitting antennas can be the same hardware unit or different depending upon many factors that will be discussed in the coming sections to decide the configuration of satellite.

1 explain different types of antenna used in satellite communication. A variety of antenna types are used in satellite communications. The shape is generally a paraboloid of revolution. Loop antennas are available in different shapes like circular elliptical rectangular etc.

Horns are also used as feeds for reflector antennas. May 2013 may 2014 dec 2014. An advantage of uhf traditionally used for military communications is that it easily penetrates deep foliage and other obstacles. The simplest physical environment occurs when the antennas are located in free space such as for communication between satellites or from an overhead satellite to ground as suggested in fig.

2 explain briefly the offset feed used with paraboloidal reflector antenna stating its main advantages and disadvantages. Parabolic antennas are used as high gain antennas for point to point communications in applications such as microwave relay links that carry telephone and television signals between nearby cities wireless wan lan links for data communications satellite communications and spacecraft communication antennas. The satellite antenna radiates electric and magnetic fields that have the radial dependence e jkr r of a spherical wave where r is the radial. Hence these are used in telecommunications and broadcasting.

They are widely used in communication links with the frequency of around 3 ghz. So parabolic reflectors increase the gain of antennas in satellite communication system. The fundamental characteristics of the loop antenna are independent of its shape.