Minimizing Radar Signatures: A Compact and Lightweight Radar Absorbing Material for Effective RCS Control

This paper presents the design of a compact, lightweight and ultrawideband Frequency Selective Surface (FSS) absorber featuring polarization insensitivity and angular stability. The design methodology leverages on an equivalent circuit model analysis combined with detailed numerical simulations, offering comprehensive guidelines. In particular, the absorber consists of two stacked resistive FSS layers and a ground plane, separated by foam dielectric spacers. The structure achieves an overall 14 mm thickness (only 0.098 λL at the lowest absorption frequency) and an extremely reduced weight (0.07 g/cm3). A −10 dB absorption bandwidth spanning from 2.1 to 18.3 GHz (corresponding to a fractional bandwidth of 158.8%) for both TE and TM polarizations under normal incidence is accomplished. Furthermore, the absorber exhibits robust, polarization-insensitive behavior for oblique incidences up to 50°, while maintaining an ultrathin electrical profile. In addition, the performance of the proposed absorber in terms of Radar Cross Section (RCS) reduction is numerically investigated through the analysis of a realistic naval target, proving excellent stealth capabilities. Finally, experimental measurements on fabricated prototypes are also performed, demonstrating good agreement with numerical results and validating the proposed approach. These remarkable features, along with the use of simple Indium Tin Oxide (ITO) based FSS patterns and low-cost foam substrates, not only streamline the fabrication process and reduce manufacturing costs, but also support large-area implementations, making the absorber highly suitable for stealth and electromagnetic compatibility applications.