A Broadband Multifunctional Reconfigurable Polarization Conversion Metasurface

In this work, a reflective polarization conversion metasurface (PCM) with symmetrical L-shaped patches is proposed which enables to switch between different polarization modes by PIN diodes, i.e., linear-to-linear (LTL) cross-polarization and linear-to-circular (LTC) polarization. Because of multimodes activated in the structure, the PCM shows an ultrawide bandwidth both for LTL and LTC polarization conversion. A microstrip line-based dc biasing network composed of radial stubs is introduced to isolate RF currents, which can resolve problems raised by RF-lumped choke inductors in the ultrawide bandwidth. A prototype with $15\times15$ units is fabricated. The simulated and measured results show that when the PIN diodes are forward biased, the PCM achieves LTC polarization conversion in the range of 5.96–15.34 GHz (relative bandwidth of 88.4%) with the axial ratio (AR) less than 3 dB; when the PIN diodes are reverse biased, the PCM achieves LTL polarization conversion in the range of 6.05–14.76 GHz (relative bandwidth of 83.75%) with the polarization conversion ratio (PCR) higher than 90%. The proposed PCM is expected to be potentially applied to a broad scanning range array, intelligent reflecting surfaces (IRSs), and remote sensing.