A Switchable Frequency-Selective Rasorber With Wide Transmission/Absorption Bands and Sharp Roll-Off Characteristics

This article proposes a switchable frequency-selective rasorber (FSR) with wide transmission, wide absorption band, and sharp roll-off performance. The structure combines a 3-D lossy dipole, a 2-D switchable lossy layer, and a 2-D switchable frequency-selective surface (FSS). By integrating p-i-n diodes into a passive FSS, a second-order switchable passband is achieved, enabling dynamic mode switching (transmission/reflection) within the operating band while maintaining broadband out-of-band reflection suppression. An equivalent circuit model (ECM) is established to validate the design, demonstrating wide absorption and tunable transmission performance. The experimental results indicate that, when the diodes are off, it offers a 20% fractional bandwidth (FBW) transmission band and absorption bands with 120.3% and 43.5% FBWs. When the diodes are on, an absorption band with FBW of 156.9% is realized, marking it as one of the most advanced switchable FSR designs.