Narrow band polarization insensitive frequency selective surface based microwave absorber

Abstract

Design, fabrication and testing of a narrow band polarization insensitive, planar microwave absorbing structure using frequency selective surface and without using any loaded resistance/resistive material are presented. The unit cell of the absorbing structure consisting of a symmetric triple square ring printed on one side of a FR4 substrate. It results efficient absorption of the incident microwave energy in X-band. The optimum design was validated by fabricating a absorbing structure array of 4 × 3 unit cells by conventional lithography process. It is then tested for normal incidence on microwave test bench set-up using WR90 waveguide. Full wave electromagnetic simulation demonstrates 99.99% microwave absorption at 9.8GHz with 1.23% absorption bandwidth. The structure shows good frequency stability for TE and TM polarizations. The simulated and measured values of absorption are found to be in good agreement. Therefore, proposed microwave absorber can be suitably used for avionics applications.