Corrections for the Effects of a Radome on Antenna Surface Measurements Made by Microwave Holography

AbstructMeasurements of the surface deviations of a parabolic antenna by microwave holography have been corrected for the effects of an enclosing radome. The largest correction, which is due to diffraction from the metal space frame, is made by using a model computed from the radome structure. This model accounts for the changing diffraction as the antenna is scanned during the interferometric mapping of the complex beam pattern. Correction for reflections from the radome panels is made by simultaneously measuring the beam pattern at multiple frequencies to provide delay discrimination to reject antenna side lobes generated by multiple reflections which arrive with delays different from that of the main beam.