Narrowband Configurable Polarization Rotator Using Frequency Selective Surface Based on Circular Substrate-Integrated Waveguide Cavity

In this letter, a narrowband configurable polarization rotator using frequency selective surface based on circular substrate-integrated waveguide (SIW) cavity is presented. Considering current distribution of dominant mode of circular SIW cavity and implementing a slot on the front surface and two orthogonal slots on the back surface of it, linear polarization is rotated as much as demanded. The position of two orthogonal slots on the back surface determines the amount of polarization rotation. Performance of the proposed structure is discussed for two different rotation amounts in Ka frequency band. Design, simulation, and optimization of the proposed structure has been carried out by CST Microwave Studio software. Finally, a prototype of structure for 45° polarization rotating is fabricated and measured. There is a great agreement between simulation and experimental results.