A Reconfigurable Frequency Selective Surface Switching between Absorption, Transmission, and Reflection, along with Frequency Tunability

Abstract

A reconfigurable frequency selective surface (RFSS) with multiple electromagnetic (EM) operations using p-i-n diodes and varactors has been presented in this paper. The proposed design comprises metallic patterns on two sides of an FR4 substrate, with varactors mounted on the top layer and p-i-n diodes on both layers to achieve tuning and switching operations. This structure offers multiple characteristics, such as absorption, transmission, and reflection, under different switching modes along with frequency-tunable functionality. These characteristics have been achieved by controlling the p-i-n diode biasing conditions, which perform various switching modes, and adjusting the varactor diode's reverse bias voltage to provide the frequency tunability for each mode. The simulated results demonstrate that in the OFF (top side p-i-n diodes)-OFF (bottom side p-i-n diodes) case, the MRFSS exhibits a bandpass response with an insertion loss of 1.8-2.9 dB from 1.68-2.56 GHz. The OFF-ON state shows a narrow-band absorber with an absorptivity ranging from 84.3 % - 96.5% in the frequency range of 1.84-2.85 GHz. The ON-OFF and ON-ON states enable partial and full reflection modes, with reflection amplitudes greater than -2.5 dB and -1.5 dB from 2.48-4.43 GHz and 2.55-4.62 GHz, respectively. This proposed RFSS structure with multiple characteristics and frequency tunability holds great potential for various applications. © 2023 IEEE.