Specular Reflection Reduction Using Periodic Frequency Selective Surfaces

This paper presents a method for controlling scattering from a surface with the use of periodic elements on a metallic ground plate. A comb reflection frequency selective surface (CR-FSS) is compared with a novel pin reflection frequency-selective surface (PR-FSS). The performance of the periodic surfaces are based on their ability to reduce specular scatter and redirect this as backscatter compared with a flat perfectly conducting (PEC) plate. The PR-FSS has comparable scattering performance when compared with the CR-FSS, despite a 90% reduction in fin material. Simulation and experimental results show that the PR-FSS is effective only for TM polarization, whereas the CR-FSS is adequate for both TM and TE polarizations. The effect of changes to the angle of incidence, height, and separation of the pins and fins are investigated. Aluminium prototypes have been manufactured and tested to provide experimental validation of the designs and are compared with simulated results. This includes full radar scattering cross sections, angle-of-incidence performance, and operational frequency bandwidth. Furthermore, suitable engineering applications of the CR-FSS and PR-FSS structures are considered.