Novel Wideband Linear-Circular Reflective Type Polarizer with Operational Band Switchabilty Spanning for X to Ka-Band Satellite Applications

In this article, a novel wideband mechanically switching linear-circular and linear-cross reflective polarization converter is proposed, covering X to K-band. The unitcell features a circular patch-loaded electric dipole forming the metallic resonator on top of the grounded FR-4 substrate. Two via-stitched capacitive pads are kept on either side of the metallic resonator for biasing. For the proof of the concept, the ON and OFF states of the diode are mimicked with and without shorting the resonating dipole with capacitive pads. In the OFF state, the polarizer converts the linearly polarized EM signal to a circular polarized with an Axial Ratio (AR) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\leq 3 ~\text{dB}$</tex> from 9.75-10.12 GHz and 11.62-21.21 GHz. In addition to this, it also performs linear-cross polarization conversion from 10.44-11.05 GHz in the X-band with a minimum 90% Polarization Conversion Ratio (PCR). While in the ON state, the polarizer performs linear-circular conversion in the upper band with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{A R} \boldsymbol{\leq} \text{3 d B}$</tex> from 9.74-10.15 GHz, 14.36-14.58 GHz, and 20.74-25.58 GHz and linear-cross with a minimum 70% PCR from 10.2-14.3 GHz. With a compact <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.051 \lambda_{L}$</tex> thickness and aerial dimensions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.211 \lambda_{L} \times 0.211 \lambda_{L}$</tex>, the polarizer is extremely miniaturized and electrically efficient. The design's unique combination of compactness and conversion performance makes it highly suitable for practical applications, embodying the novelty of the proposed concept.