- It is a type of microwave antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves to the receiver in its focal point.
- A parabolic antenna is composed of a parabolic dish along with antenna feed. The various arrangements are used as feed for the parabolic reflector antenna.
- The parabolic antenna includes center feed with spherical cells, center feed with horn antenna, Cassegrain feed, etc.
- In parabolic antenna is used as a transmitter and as the receiver.
- The above figure shows a parabolic reflector as a transmitter. As shown feed radiates power into a reflecting surface having a parabolic shape.
- In a parabolic antenna, the reflector reflects microwave power along the antenna axis which is the direction of the beam.
- Likewise, waves falling on the dish are concentrated towards the feed placed at the focal point of the dish.
- This way receiver is carried out by the parabolic reflector antenna.
Advantages of Parabolic Reflector Antenna
- It can be used both as a transmitting antenna and receiving antenna due to the principle of reciprocity.
- The feed can be used in various modes with a parabolic reflector viz. center feed, Cassegrain feed, or offset feed. Each of these configurations has its respective benefits and applications.
- Smaller size and low cost.
Disadvantages of Parabolic Reflector Antenna
- Feed antenna and reflector disc block a certain amount of radiation from the main parabolic reflector antenna. This is about 1 to 2%.
- The design of a parabolic reflector is a complex process.
- Despite the feed horn at focus and uniform illumination, a certain amount of power from the feed is bound to slop over the edges of the parabolic reflector. This power is responsible to form side lobes in the radiation pattern.
- Surface distortions can occur in a very large dish. This is reduced by using a wide mesh instead of a continuous surface.
- To achieve the best performance results, the feed should be placed exactly at the focus of the parabolic reflector antenna. This is difficult to achieve practically.
Application of Parabolic Reflector Antenna
- It is used in Direct broadcast or satellite television, Terrestrial microwave links, Satellite communications, and Radio astronomy.