Parabolic Dish Antennas are used in satellite communications to transmit, receive or both transmit and receive signals. Feed assemblies are designed and installed in the center of the main dish to radiate transmit signals or collect receive signals. Polarization of the signals are also considered when selecting a feed assembly and the typical types are Horizontal (H), Vertical (V), Right hand Circular (RCP) or Left hand Circular (LCP) polarizations. These antennas have a gain that is based on the diameter of the main dish and the frequencies used.  An acceptable course approximation of the antenna gain is 1 dB per foot.

When used for receive, the antenna operates by reflecting the receive signals from a main dish to a sub reflector that focuses the signal and reflects it onto a feed assembly. The output signals from the feed assembly is connected to the receive amplifier.

When used for transmit, the output from the transmit amplifier is connected to the transmit feed.  The transmit signal is radiated from the feed assembly that is focused on the sub-reflector. Transmitted signals are then reflected from the sub reflector to the main dish  and radiated from the main dish to the satellite it is pointed at.

Curvature of the dish and distance from the main dish to the sub-reflector are selected based on the frequency of the signals to be received or transmitted.  The diameter is selected for the gain required from the antenna. In the direct TV receive only application the antenna is mounted in a fixed position. Antenna drive systems are used to allow repositioning of the antenna and can range from a limited motion control system using an X and Y coordinate system to a full motion antenna drive using an azimuth and elevation coordinate system.