A Ka-Band Polarization Rotating Multilayer Reflector for Polarimetric Radars

A multilayer polarization rotating reflector with improved performance based on a previously designed singlelayer structure for polarimetric radar application is presented. The introduced frequency selective surface allows an incident electromagnetic wave with linear polarized electric field vector to be rotated by 90° depending on the frequency. The presented design is developed for Ka-band radars and consists of unit cells with slot coupled SIW cavities optimized for 45° oblique incidence. The general use of polarization rotating surfaces is introduced, frequency bands are defined and limitations of the singlelayer structure are discussed. For improving the filter performance, an additional substrate layer with resonant patch antenna elements is applied which increases the filter order. A simulation model is constructed and optimized with CST Microwave Studio. For evaluation of the presented concept, a reflector sample is fabricated and measured. Measured S-parameters prove the functionality of the multilayer structure.