Cassegrain Antenna

A Cassegrain antenna is a dual-reflector antenna configuration in which a parabolic main reflector directs incoming radiation onto a convex hyperboloidal sub-reflector, which in turn redirects the energy to a feed located near the vertex of the main reflector and coupled to a waveguide. On transmission, the signal path is reversed. In contrast to the Gregorian antenna, the Cassegrain uses a convex rather than concave sub-reflector.

Cassegrain antennas enable compact feed assemblies and are well suited to high-frequency, high-gain applications. A key advantage of the Cassegrain configuration is that the feed and receiver electronics can be located close to the main reflector vertex rather than at the prime focus, reducing feed-line losses and easing mechanical and thermal design. Cassegrain antennas are widely used in satellite communications systems.