Case study of active array feed compensation with sidelobe control for reflector surface distortion

The feasibility of electromagnetically compensating for reflector surface distortions has been investigated. The performance characteristics (gain, sidelobe level, null location, beamwidth, etc.) of large communication antenna systems degrade as the reflector surface distorts mainly due to thermal effects from a varying solar flux. The techniques described can be used to maintain the design performance characteristics independently of thermal effects on the reflector surface. It is assumed that the surface characteristics (x, y, z, its first and second derivatives) under distortion conditions are known. Surface error compensating techniques with an array feed are examined using an offset parabolic reflector geometry and a sinusoidal distortion profile.<>