Design and Verification of Cross-Polarization Compensation Feed for Single Reflector Compact Antenna Test Range over a Wide Bandwidth
Measurement applications using a Compact Antenna Test Range (CATR) often require low cross-polarization or high polarization purity of the Quiet Zone (QZ). This requirement is often the main motivation for choosing the more complex and thus expensive compensated dual reflector system as opposed to the simpler and cheaper single reflector system. In this paper, a novel wide-band, conjugate matched feeding concept is presented. The concept aims at the cancellation of the geometrical optics cross-polar component in the QZ of a single reflector CATR. The concept is valid for both side and edge fed configurations of the CATR in dual simultaneous polarizations. The conjugate matched feeding concept, suitable for a standard CATR system, is described in detail and the crosspolarization cancellation properties of the proposed widebandwidth feed system is discussed. The concept is initially verified and the solution consolidated using numerical simulation of the reflector and full wave simulation of the feed system. The achievable wide-band cross-polar discrimination of 40dB in the QZ is confirmed on an operational bandwidth of 1:1.5. The conjugate matched feeding concept is then validated by a reduced hardware demonstrator and measurements. The target crosspolar discrimination of 40dB is confirmed by QZ probing of a standard single reflector CATR system.