A Function-Switchable Broadband Absorber/Polarization Converter Based on an Active Metasurface

A novel function-switchable active metasurface is proposed, whose unit cell is a combination of a snowflake-shaped resonator and dual L-shaped resonator embedded by PIN diodes and lumped resistors, by controlling the bias voltage of these diodes, the functionality can be switched between broadband perfect absorption and polarization conversion. The simulation results show that when all the diodes are in on-state, the proposed metasurface exhibits perfect absorption from 3.5GHz to 7.32GHz with 90% absorptivity; when all the diodes are in off-state, the metasurface can convert the co-polarization wave to cross-polarization wave from 2.02GHz to 6.62GHz with polarization conversion ratio (PCR) over 90%. In addition, the surface current distributions are demonstrated to explain the physics mechanism of perfect absorption and polarization conversion.