Polarization-Insensitive Absorptive/Transmissive Reconfigurable Frequency Selective Surface With Embedded Biasing

In this letter, a polarization-insensitive absorptive/transmissive reconfigurable frequency selective surface (RFSS) using p-i-n diodes is presented. The RFSS structure incorporates two periodically arranged metallic patterns on both sides of an FR4 dielectric substrate, where the p-i-n diodes are aligned symmetrically on the bottom surface. Depending upon the diode biasing conditions, the geometry behaves as a radar absorber and a bandpass filter under different working states. The simulated response exhibits a near-unity absorption response (having absorptivity of 93.51%) at 6.93 GHz during
on
state of the diode, whereas the incident electromagnetic wave gets transmitted through the structure at 5.62 GHz during
off
state. An embedded biasing circuitry has also been developed comprising metallic vias and inductors, such that the geometry displays polarization-insensitive and angularly stable responses for both states. The structure has been analyzed with the help of circuit modeling and other parametric variations to explain the switching methodology. A prototype has been fabricated and measured using the parallel-plate waveguide technique, which results in a good agreement with the simulated responses. Such RFSSs can be marked as a potential element for various radome applications.