Tri-reflector antennas with no cross-polarized component
Abstract
Since offset antennas have good wide angle characteristics, they are used frequently for ground stations in microwave communications. However, when the frequency reuse is considered via two orthogonal polarizations, the cross-polarization components generated on the reflector surface create a problem. A method was reported in which the cross-polarization components are cancelled in the geometric optics sense in the offset Cassegrainian and Gregorian systems. In such a method, the degree of freedom in design is not large. For instance, the inclination of the axis of the conical horn used as the primary radiator is restricted. This paper studies tri-reflector antennas in which the degree of freedom is larger. The geometrical condition for eliminating the cross polarization is derived and the shape of the reflector system satisfying the condition is found. To confirm the theoretical results, an antenna has been constructed. The cross-polarization components are less than about -30 dB and hence the validity of the theory has been confirmed.
- Publication:
-
Electronics Communications of Japan
- Pub Date:
- August 1985
- Bibcode:
- 1985JElCo..68...85U
- Keywords:
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- Antenna Radiation Patterns;
- Cross Polarization;
- Geometrical Optics;
- Microwave Antennas;
- Reflector Antennas;
- Reflectors;
- Amplification;
- Polarization (Waves);
- Communications and Radar