Millimeter-Wave Half Mode Substrate Integrated Waveguide Frequency Scanning Antenna With Quadri-Polarization

A millimeter-wave frequency scanning antenna, which is capable of dynamically changing the state of polarization thereby providing four modes of operation, is investigated and synthesized in the half mode substrate integrated waveguide (HMSIW) technology. This antenna is a planar passive circuit and fabricated by the low-cost PCB process. It is able to operate in either linear or circular polarization (LP or CP), depending on the requirements of its specific application. A wide angular region can be covered by 3 dB beam-widths of the continuous scanning LP beams and CP beams varying the frequency. It has good performance validated by measurements and has nearly a half reduction in size compared with the substrate integrated waveguide (SIW) version. The axial ratios of CP modes are excellent in the main beam directions within whole frequency band of interest and the isolations between each channel are good as well.