In this paper, a novel high-shielding-effectiveness energy-selective surface (HSE–ESS) is proposed. In previous solutions regarding energy-selective surfaces (ESSs) presented in the literature, PIN diodes are usually employed as nonlinear transmission components; however, these diodes may be burnt by powerful high-power microwave (HPM) beams, causing ESSs to lose their shielding effectiveness (SE). To date, no studies have focused on maintaining the SE performance of ESSs after PIN diode failure. To address these limitations, we introduce shape memory alloys (SMAs) into ESS design. The consequences of PIN diode failure are offset by the physical deformation of SMA components caused by high-amplitude-current heating. This characteristic, featuring 30 dB SE, can be defined as high shielding effectiveness (HSE). After completing the design and performing accurate numerical simulations, we fabricated a prototype using PCB technology and characterized it in an anechoic environment, verifying the overall method. In particular, the SMA components proved to be an effective medium for guaranteeing electrical continuity under thermal stress conditions, thus paving the way for their extended adoption in ESSs by substituting or acting as a back-up for PIN diodes. Overall, this approach enhances the reliability and SE of ESSs by adding SMA components.

In this paper, a novel low-complexity and cost-effective switchable frequency selective rasorber (SFSR) with polarization-independent switching capability is proposed. To our best knowledge, previously reported electronically reconfigurable and polarization-independent SFSR configurations requires at least 3 distinct layers with no less than 20 SMD lumped components for each unit-cell, causing high cost and fabrication complexity. Conversely, the herein developed switchable rasorber contains only 2 layers with 6 SMD lumped elements for each unit-cell, thus significantly simplifying fabrication and reducing overall cost. To achieve the independent control over TE and TM polarizations, we separate the structure design in perpendicular directions. Two switchable bands are accomplished, whose working mode can be changed from transmission to absorption and reflection to transmission respectively, while only one is usually possessed by previous literature results. By switching the operating state of PIN diodes, the SFSR working mode type is A–T/A–A–R/T. For A–T–A–R mode, it exhibits S 11 ⩽ − 10 dB low reflection band of 2.89–8.74 GHz, with 1.17 dB insertion loss. For A–A–A–T mode, it exhibits low reflection band of 3.67–8.2 GHz. Besides, the SFSR has angle stability of 30 ∘ . After the design process and numerical simulations evaluation, prototypes are fabricated through PCB technology and characterized in anechoic environment, confirming the overall approach. This work improves about 43% cost effectiveness under same capabilities and it is particularly suitable for all the applications requiring low-complexity and cost-effective fabrication, such as unmanned equipment and antennas radome.

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.