Beam waveguide antenna

Principle of operation

Beam waveguide antennas are used in large radio telescopes and satellite communication stations as an alternative to the most common parabolic antenna design, the conventional "front fed" parabolic antenna. In front feed, the antenna feed, the small antenna that transmits or receives the radio waves reflected by the dish, is suspended at the focus, in front of the dish. However, this location causes a number of practical difficulties. In high performance systems, complex transmitter and receiver electronics must be located at the feed antenna. This feed equipment usually requires high maintenance; some examples are water cooling for transmitters and cryogenic cooling for sensitive receivers. With the large dishes used in these systems, the focus is high off the ground, and servicing requires cranes or scaffolds, and outdoor work with delicate equipment high off the ground. Furthermore, the feeds themselves 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 these problems by locating the feed antenna in a "feed house" at the base of the antenna, instead of in front of the dish. The radio waves collected by the dish are focused into a beam and reflected by metal surfaces in a path through the supporting structure to the stationary feed antenna at the base. The path is complicated because the beam must pass through both axes of the altazimuth mount of the antenna, so turning the antenna does not disturb the beam.

History

Beam waveguides, which propagate a microwave beam using a series of reflectors, were proposed as early as 1964.{{cite journal |name-list-style=amp |name-list-style=amp |book-title=Antennas and Propagation Society International Symposium, 1970 |name-list-style = amp |access-date = 2011-03-22 |archive-url = https://web.archive.org/web/20110614133812/http://deepspace.jpl.nasa.gov/technology/95_20/95-20.pdf |archive-date = 2011-06-14 |url-status = dead

The first full scale beam waveguide antenna was the 64 meter antenna at the Usuda Deep Space Center, Japan, built in 1984 by the Japan Aerospace Exploration Agency.{{cite journal |name-list-style=amp

References

References

1. Chapter 3 of ''Low-Noise Systems in the Deep Space Network''
2. link. (October 8, 2012 Aerospace report TR-0200(4230-46)-1, L.A. Hoffman, Electronics Research Lab, October 1968, page 69.)