Enhanced Hidden Object Detection with a Circularly Polarized W-band Imaging Radar System

We present an experimental W-band imaging radar demonstrator to transmit and receive circular polarization from 88 to 110 GHz. It illuminates test objects with a circularly polarized lens antenna with 30 dBi gain and 3.5 degree beamwidth. For the detection of hidden objects, specific practical aspects of the polarizer design and measurement need to be addressed, since polarizer performance is degraded by reflections between the input and output ports. A measurement scheme for characterization of a polariser by measurement is presented. The results presented here on imaging in the W-band system demonstrate a clear benefit of circular polarization over a linearly polarized system, despite the increased system complexity.