This article examines a substrate integrated waveguide (SIW) cavity-backed circularly polarized diversity antenna. In the proposed novel antenna, parasitic patch and reconfigurable diodes are used to change polarization diversity from left hand to right hand and vice versa, respectively. In addition to, what makes distinctive proposed antenna in compared with similar works, is ability to change linear polarization from a SIW slot to circularly polarization by a parasitic patch. Chopping off two diagonally opposite corners makes the resonance frequency of the mode along this diagonal to be higher than that for the mode along the unchopped diagonal. By exciting parasitic patch with a slot along axes of it the orthogonal modes are generated which causes to CP. The comparison between simulation and measurement results validate antenna design. The measured impedance BW (VSWR < 2) for state 1 and 2 are 22.18% (11.86-14.82 GHz) and 21.68% (11.88-14.77 GHz), and The measured 3-dB AR BW for states 1 and 2 are about 11.46% (11.43-12.82 GHz) and 11.23% (11.43-12.79 GHz), respectively. Finally, the measured maximum gain is 9.81 dBic.

Saeid Karamzadeh, Vahid Rafiei, Hasan Saygin, ” A novel circularly polarized cavity backed SIW antenna with capability to change polarization diversity by a reconfigurable polarized structure “, International Journal of RF and Microwave, Computer-Aided Engineering, 2017;  https://doi.org/10.1002/mmce.21113.