Single‐Layer Infrared Low‐Emissivity Frequency Selective Surface and Bi‐Stealth Metasurface Design Using Micro Metal Patch

Abstract Two‐deimensional (2D) periodic structures such as frequency selective surfaces (FSS) are widely used for controlling the transmission, reflection, and scattering of electromagnetic waves. Applications including low‐emissivity (low‐E) glass for energy‐efficient buildings and metasurfaces for reducing radar cross section (RCS) and infrared signatures require both frequency selective and low‐E properties. This work presents a cost‐effective methodology for a single‐layer low‐E FSS (SLLE‐FSS) that satisfies these requirements. The design incorporates micro metal patches (MMPs), an array of metallic patches much smaller than the wavelength, which remain transparent in the RF band while reflecting most IR energy. By integrating MMPs within the same layer as the FSS, a high metal filling ratio is achieved without compromising RF characteristics. To address the computational cost caused by the scale difference between FSS and MMPs, equivalent circuit models (ECMs) are introduced for efficient design of both transmission‐ and reflection‐type structures. The proposed approach is validated through simulations and measurements of MMPs, SLLE‐FSS prototypes, and an SLLE‐based artificial magnetic conductor (SLLE‐AMC) for IR–radar bi‐stealth metasurfaces. Results confirm that the methodology enables single‐layer structures combining frequency selectivity and low‐E properties, offering broad applicability to multifunctional electromagnetic and optical systems.