Independently Switchable Rasorber With Wide Transmission and Low-Reflection Bands Under Dual Polarization

Switchable frequency selective rasorbers (FSRs) have gained significant attention for their ability to switch passbands into absorption bands. However, increasing their functionality or switchable state while maintaining stable wideband transmission and low reflection remains challenging. Therefore, this work proposes a three-layer FSR architecture that achieves switchable wide-passband in wide low-reflection bands and state-of-the-art independent switchability under dual polarization. First, for the bottom layer, a second-order inductively coupled frequency selective surface (FSS) with active diode loading on the uppermost layer can switch from wide passband to reflections. Second, for the middle layer, the switchable impedance layer with a low-
${Q}$
parallel resonator can preserve the passband or absorb previous in-band electromagnetic (EM) waves. Third, for the top layer, theoretical analysis confirms that an additional nonswitchable impedance layer must be introduced to achieve extended low reflection bandwidth during various switching states. Note that a polarization-isolated bias network is merged into the structural design to provide polarization-independent switchability for the passband. Finally, experimental results agree with simulations, demonstrating the proposed FSR device exhibits excellent performance, including four switching operating states, a wide 1-dB passband, 45° transmission angular stability, and a consistently wide low-reflection band in all rasorbing or absorbing states.