Transreflector antenna design for millimeter-wave wireless links

A transreflector antenna is compact, like a Cassegrain reflector antenna, but it has the high efficiency and low sidelobe levels of a prime-focus reflector. We describe in detail how to design a transreflector antenna and its components, including the transreflector, the polarization twist-reflector, and the feed horn. As validation of our design methods, we have developed a 9.5-in transreflector antenna with a focal length of 3.2 in. We can operate the antenna at the Ka or V band, depending on whether we use a Ka- or V-band feed horn and twist-reflector. In both bands, the measured efficiency of the antenna exceeds 50%, the peak sidelobe level is below -17 dB, and the principal-plane cross-polarization rejection exceeds 33 dB. The input return loss is greater than 12.5 dB across each band of operation.