An imaging beam waveguide feed
Abstract
A pseudo-frequency-independent beam waveguide feed has been designed and built to accommodate a new liquid-helium-cooled millimeter wave radio astronomy receiver in the side cab of the Crawford Hill 7-m antenna. This enables the antenna to be tilted without tilting the liquid-filled receiver. Comparison with the old vertex-cab feed indicates very little measured transmission loss through the beam waveguide. The frequency independence is based upon the Fresnel zone imaging principle. Design procedures and practical bandwidth limitations are explained. An explicit expression for the third-order terms of an offset reflector surface clarifies the approximation of a lens by an offset reflector.
- Publication:
-
IEEE Transactions on Antennas and Propagation
- Pub Date:
- July 1983
- DOI:
- 10.1109/TAP.1983.1143090
- Bibcode:
- 1983ITAP...31..614C
- Keywords:
-
- Antenna Design;
- Antenna Feeds;
- Microwave Antennas;
- Millimeter Waves;
- Reflectors;
- Waveguides;
- Liquid Helium;
- Noise Reduction;
- Radio Astronomy;
- Transmission Loss;
- Electronics and Electrical Engineering