Antennas Used In Satellite Communication

1 explain different types of antenna used in satellite communication.

Antennas used in satellite communication.

The most widely used narrow beam antennas are reflector antennas. An advantage of uhf traditionally used for military communications is that it easily penetrates deep foliage and other obstacles. Explain with neat diagram the antennas used in satellite communication. For full earth coverage from a geostationary satellite a horn antenna is used.

Horns are also used as feeds for reflector antennas. The shape is generally a paraboloid of revolution. So parabolic reflectors increase the gain of antennas in satellite communication system. 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.

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. 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. 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. Uhf communications satellites often use downlink frequencies around 250mhz and uplink frequencies around 310 mhz.

A variety of antenna types are used in satellite communications. Hence these are used in telecommunications and broadcasting. They are also used in radio telescopes. They are widely used in communication links with the frequency of around 3 ghz.

These antennas can also be used as electromagnetic field probes in the microwave bands. 2 explain briefly the offset feed used with paraboloidal reflector antenna stating its main advantages and disadvantages. Loop antennas are available in different shapes like circular elliptical rectangular etc. The fundamental characteristics of the loop antenna are independent of its shape.

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. Satellite borne communications antennas are located very far from their service area on the earth. Antennas in satellite communication types of antenna system use in satellite communication.