Design and optimization of hybrid structures based on resonant and lossy absorbers for improved RCS performance in high-curvature structures

In this study, a hybrid structure combining resonant and lossy absorbers is proposed to improve radar cross section (RCS) reduction performance in high-curvature structures. The absorption characteristics of the resonant and lossy absorbers are first evaluated through simulations, whereas RCS simulations assess the reduction performance of the conformal and hybrid structures. The conformal structure employs a resonant absorber composed of conformally networked carbon nanotube–glass fabric and carbon nanotube–polymethacrylimide foam. Although the resonant absorber exhibits high absorption at the design frequency, geometric constraints in the high-curvature tip region increase the local effective thickness, shift the resonance condition, and degrade the absorption performance. The hybrid structure replaces this tip region with a lossy carbon nanotube–polymethacrylimide foam absorber that is less sensitive to thickness variation. A staged parametric analysis examines the thickness, height, and carbon nanotube content of the lossy absorber, followed by combined optimization of the thickness and height. The optimized structure (H8–T40–M3.0) achieves improvements ranging from 15.1 to 52.0% in RCS reduction performance relative to the conformal structure under horizontal–horizontal and vertical–vertical polarizations at incident angles of 0°, 15°, 30°, and 45°. The maximum improvement of 52.0% occurs under vertical–vertical polarization at normal incidence. Current density and power loss distributions show that the hybrid structure reduces current concentration at the tip and extends electromagnetic energy dissipation into the internal lossy absorber. These results demonstrate that combining resonant and lossy absorption mechanisms mitigates resonance mismatch and improves RCS reduction performance in high-curvature structures.