Reduction of sidelobe level of reflector antennas by covering feed struts with a periodic structure
Abstract
An effective method is developed in order to reduce the part of the far sidelobes originating from the scattering of the struts in rotationally symmetric reflector antennas such as prime-focus or Cassegrain antennas. This method is based on completely eliminating the specular reflection from a strut and backscattering all incident power in the direction of incidence. A circulator in the feeding waveguide is employed to suppress the interference due to the wave scattered back into the feed horn. A theoretical approach is presented and applied to design struts of finite transverse size for reflector antennas with low far sidelobes. The measured pattern of a prime-focus paraboloidal antenna at 11.5 GHz is presented. It is found that with smooth struts the sidelobe level at 2-alpha (the flare angle of the radiation pattern due to the struts) is about -35 dB, whereas it is better than -48 dB with struts provided with a corrugation boundary. The sidelobe level caused by the struts in other planes of the radiation pattern is also significantly reduced.
- Publication:
-
Electronics Letters
- Pub Date:
- May 1983
- DOI:
- 10.1049/el:19830257
- Bibcode:
- 1983ElL....19..371H
- Keywords:
-
- Antenna Design;
- Parabolic Antennas;
- Reflector Antennas;
- Sidelobe Reduction;
- Struts;
- Angular Distribution;
- Incident Radiation;
- Optimization;
- Reflectors;
- Communications and Radar