Wideband, polarization independent electromagnetic wave absorber using cross arrow resonator and lumped SMD resistors for C and X band applications

Abstract

In this work, a polarization independent and wideband electromagnetic (EM) waves absorbing frequency selective surface (FSS) structure is presented. The unit cell of the proposed FSS consists of an assembly of cross arrow resonators with four SMD resistors mounted on it, to enhance the absorbance bandwidth. This unit cell also possesses a four-fold symmetry which makes it polarization insensitive. The designed unit cell is compact with the length and width dimensions as 0.19λL × 0.19λL, and thickness of 0.13λL, where λL is the guided wavelength corresponding to the lowest operating frequency. The proposed absorber is theoretically and experimentally tested for its absorbance, cross-polarization level, and radar cross section (RCS) characteristics. The computer-aided simulation and practical measurements indicate that the proposed absorber offers more than 90% (with a fractional bandwidth of 93%) absorbance for normal incidence at 4.5–12.4 GHz frequency band. The cross-polarization reflection coefficient analysis indicates that the proposed FSS configuration behaves as an absorber and not a polarization convertor. The input impedance plot, surface current distribution, and E-field distribution of the unit cell were also analyzed and presented to understand the absorbance mechanism. The RCS of the proposed FSS is compared with the RCS of a reflective (metallic) sheet to analyze its suitability for practical applications (RCS reduction) within the working band. The 3D simulated and 2D calculated RCS results indicate that the proposed FSS is suitable for wideband EM wave absorber applications.