High-Shielding-Effectiveness Frequency-Selective Rasorber with Polarization-Independent Switching Capability

In this paper, we propose a novel high-shielding-effectiveness frequency-selective rasorber (HSE-FSR) that combines the advantages of a frequency-selective rasorber (FSR) and an energy-selective surface (ESS). The proposed HSE-FSR contains two layers—a lossy layer that implements a conventional FSR for stealth performance and an ESS layer for high-power beam shielding effectiveness (SE)—both of which employ PIN diodes as switchable components. However, PIN diodes can be severely damaged by high-power microwave (HPM) beams or experience other electromagnetic compatibility issues causing elevated currents to flow into them. To maintain SE performance after an eventual PIN diode failure, we added shape-memory alloy (SMA) components in the ESS layer as a backup. This characteristic, combined with a 30 dB SE level, is representative of high shielding effectiveness (HSE). As a result, the HSE-FSR contains three working modes: FSR, shielding and absorbing (SA), and HSE. Notably, the proposed HSE–FSR possesses polarization-independent switching capability for the FSR mode. After a careful design process carried out with commercial electromagnetic software, numerical simulations are performed to validate the overall methodology. The obtained results confirm the approach’s effectiveness and show that the proposed HSE–FSR has better stealth and SE performance than the current state-of-the-art.