Multilayer Energy Selective Surface With Wide Operational Band and High Shielding Effectiveness Based on Second-Order Filter

In this article, a novel multilayer energy selective surface (ESS) with an ultrawide operational band and high-power isolation composed of nonresonant unit cells is presented. A simple second-order filter circuit is designed and optimized first. Then, an ESS with metallic patches and octagonal rings is designed to match the second-order filter circuit under the guidance from circuits to metasurfaces. The ESS performs a nonlinear response for the low-power and high-power incident microwaves. The operating properties of the ESS are generated by the interlayer resonance of nonresonant capacitive patches and inductive octagonal rings. Circuit and full-wave simulations are conducted, respectively, and their results show relatively good consistency. Meanwhile, two ESS prototypes are fabricated, and experiments are conducted under different incident power levels in WR-137 and WR-90 waveguides. According to the simulated and experimental results, the proposed ESS has a wide 1 dB operational band covering 5.8–9.0 GHz for low-power incident wave, and high shielding effectiveness of 22 dB under high-power microwave. Particularly, the maximum SE reaches up to 25.7 dB at 9 GHz. This article provides a feasible and promising method for providing strong electromagnetic protection for broadband electronic devices.