A Multifunctional Metamaterial-Based Dual-Band Isotropic Frequency-Selective Surface

A novel design of a thin isotropic frequency-selective surface (FSS) composed of a subwavelength electromagnetic metamaterial structure is proposed and its application as hollow waveguide filter and as perfect absorber are discussed. In the single-layer FSS design, unit cells of a T-type resonator inside a rectangular split-ring resonator are arranged as periodic arrays to operate in the X- and Ku-bands. Two design configurations are proposed and optimized to exploit their distinctive characteristics. The first FSS is designed with a single element unit cell structure to have a polarization-dependent response and the second design has quad elements, rotated by 90° to achieve polarization-independent behavior. The FSS design composed of two resonators offers tunability and control over the resonance frequencies. The structure shows incident angle stability and polarization stability at the resonances. It has multiple reflective and antireflective bands with low insertion loss. To use the FSS as a perfect absorber, it has been optimized to obtain large absorption of incident waves at 7.82 GHz. The proposed structures have been fabricated in the form of FSSs and rectangular hollow waveguide filters. Simulated and measured results are compared and good agreement is found. Finally, a comparison to different FSSs from the literature is also presented. The proposed structures can be used in reflectors, sensors, radomes, and antireflection coatings.