Ultra-wideband radar cross section reduction using amplitude and phase gradient modulated surface

Abstract

In this paper, an amplitude and phase gradient-modulated surface is introduced to design a low cost and simple radar cross section (RCS) reducer metasurface. The simultaneous gradual amplitude and phase differences between adjacent unit cells achieve more degrees of freedom in the design approach, which leads to bandwidth enhancement of RCS reduction. A dual-layer stacked patch unit cell analyzed with a transmission line method is proposed to design the different required unit cells. The sinusoidal modulation applied on top and bottom layers of two stacked FR-4 substrates is used to realize the unit cells with gradual amplitude and phase variations. Finally, an ultra-wideband dual-layer stacked modulated surface composed of 26 × 26 unit cells is fabricated to demonstrate the idea. This surface achieves more than 10 dB RCS reduction from 9 GHz to 40.7 GHz (128%) for normal incident waves. Moreover, this surface has more than 118% and 88% RCS reduction bandwidths for transverse magnetic and transverse-electric obliquely polarized waves, respectively. Low profile, low cost, lightweight, and a simple assembling procedure are the main specifications of the proposed structure rather the state-of-the-art references, which candidate it as an ultra-wideband monostatic RCS reduction surface in practical applications.