A wideband reconfigurable frequency selective surface switching among transmission, absorption, reflection, and rasorber operations

A reconfigurable frequency selective surface (RFSS) exhibiting wideband electromagnetic (EM) characteristics using p-i-n diodes and resistors has been presented in this paper. The unit cell design comprises a two-layered structure with metallic patterns engraved on both sides of each substrate layer, which are separated by an air spacer. Diodes are carefully mounted on the top side of layer 1 and bottom side of layer 2, supported with bias circuits. With precise control in the bias voltage across the diodes, four different EM operations, such as transmission, reflection, absorption, and rasorber are realized exhibiting wideband characteristics. The simulated results illustrate that during the OFF (p-i-n diode on layer-1)-OFF (p-i-n diode on layer-2) case, the RFSS behaves as a rasorber with an insertion loss of 2.1 dB at 2.69 GHz (in the transmission window) and a wideband absorption of more than 80% absorptivity from 4.76-6.34 GHz (in the absorption window). The OFF-ON state presents a wideband absorption with an absorptivity greater than 80% in the frequency range of 3.25-6.05 GHz. The ON-OFF state exhibits a wideband transmission characteristic with an insertion loss of less than 2 dB ranging from 2.41-4.49 GHz. The final ON-ON state represents the reflection behavior with a reflection amplitude lower than -2.8 dB for the entire frequency range. Thus, the proposed RFSS structure exhibits multiple wideband characteristics, thus showing huge prospects for various defense and civil applications.