A Switchable Frequency Selective Rasorber with a Broad Transmission Window at the X-Band

This paper proposes a switchable polarization-insensitive frequency selective rasorber (FSR) within the X-band. The FSR comprises a lossy layer, a lossless layer, and an intermediate air layer. The lossy layer consists of metal patches, folded wires, and lumped resistors, while the lossless layer is formed with square and cross patches loaded with PIN diodes. An equivalent circuit model (ECM) has been developed to analyze and verify the working principle of the system. By altering the state of the PIN diodes, it is feasible to switch between absorbing and transmitting modes. In the rasorber mode, the switchable FSR attains a transmission window ranging from 10.13 to 12.27 GHz with a minimum insertion loss below 2 dB and a broad absorption band covering 5.79-15.37 GHz. When switched to absorber mode, the passband is negated, and the FSR exhibits a low transmission band from 10.68 to 18.00 GHz. This innovation can improve the omni-directional stealth capability and battlefield survivability of radar systems, possessing substantial research importance and practical applications.