Studies on design and development of multifunctional reconfigurable frequency selective surfaces for advanced electromagnetic applications

Abstract

Over the past few decades, research on frequency selective surfaces (FSSs) has grown rapidly because of their importance in stealth technology, radar systems, and electromagnetic (EM) shielding. An FSS is a periodic array of metallic elements that controls EM wave behavior such as transmission, reflection, and absorption, based on its geometry, polarization, and angle of incidence. Conventional FSS designs are restricted to a single fixed function, which limits their practical use. With the rapid expansion of wireless communication systems and modern radar platforms, there is a growing demand for compact and multifunctional reconfigurable frequency selective surfaces (RFSSs) that can perform various EM functions like absorption, transmission, and reflection- either simultaneously or selectively within a single structure. To realize this flexibility, FSS designs are engineered using various reconfigurable techniques, exhibiting different EM responses in real-time scenarios. In advanced communication and sensing environments, where different EM functionalities are required across distinct frequency bands or at different time instants within the same band, such RFSS designs hold strong potential. For example, an RFSS with switchable transmission-reflection characteristics can selectively permit desired signals in the transmissive state for adaptive wireless links, while it can reject or redirect unwanted signals in the reflective state improving link security.