Dual-Band Frequency-Selective Polarizer With Orthogonal Polarizations Using Perturbed SIW Cavities

A dual-band frequency-selective (FS) linear rotation polarizer leveraging a substrate-integrated waveguide cavity technology equipped with two perturbation techniques is introduced. The FS polarization rotator consists of a square cavity divided into two subcavities: a triangular cavity positioned next to an irregular pentagon cavity, connected by a row of via in the corner of the cavity. Another perturbation, a metallic vias hole inside the irregular pentagon cavity, helps reduce unwanted resonance frequencies near the main operation bands. Rectangular surface slots, arranged in parallel in front of the alternating structure, facilitate the coupling of incident linear electromagnetic (EM) waves inside the cavities. The back and front irregular pentagonal cavity slots are aligned parallel, allowing EM waves to pass through while preserving the polarization. The triangular cavity back slot is perpendicular to its front one, resulting in a polarization rotation. By controlling the poles originating from cavity resonant frequencies and slots, significant performance enhancements were achieved. A rigorous analysis, meticulous design, fabrication, and measurement of the proposed planar rotator validated its performance. The good agreement between measured and simulated results confirms the dual-band polarizer’s efficacy, showcasing high polarization isolation.