A beam waveguide antenna is a specific variety of parabolic dish that sends the transmitted or received signal from a stationary transmitter or receiver to a movable dish by means of a beam waveguide. With a conventional parabolic antenna, the transmitter or receiver is mounted at the focus

Focus (optics)

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...

, and moves as the antenna is repositioned to track specific targets. While this works well, the focus is an inconvenient spot to mount transmitters and receivers, since they are complex and high maintenance, and often require special needs such as water cooling for transmitters and cryogenics

Cryogenics

In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit,...

 for sensitive receivers. Furthermore, these units have to be designed to handle outdoor conditions such as rain and large temperature swings, and to work while tipped at any angle. The beam waveguide antenna addresses this problem by relaying the signal to a fixed location in the base of the antenna, no matter where the antenna is pointing.

History

Beam waveguides, which propagate a microwave beam using a series of mirrors, were proposed as early as 1964. By 1968, there were proposals to handle some of the signal path in pointable antennas by these techniques. By 1970, a fully beam-waveguide approach was proposed for satellite communication antennas. At first, this approach was believed to tradeoff performance for convenience, but further analysis showed the waveguide system could be built with very low losses. This led to scientific use, first at 64 meter antenna at the Usuda Deep Space Center

Usuda Deep Space Center

Usuda Deep Space Center is a facility of the Japan Aerospace Exploration Agency It is a spacecraft tracking stationopened in October, 1984. The main feature of the station is a 64 meter beam waveguide antenna...

. After the Jet Propulsion Lab (JPL) tested this antenna and found it better than their conventional 64-meter antennas, they too switched to this method of construction for all subsequent antennas of their Deep Space Network

Deep Space Network

The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

(DSN).