Wideband, Very Low RCS Engineered Surface With a Wide Incident Angle Stability

Abstract

In this communication, broadband, low radar cross section (RCS) engineered surface with the ability of operating over a wide range of oblique incident angles is presented. Two types of artificial magnetic conductor (AMC) unit-cells with a 180° ± 37° reflection phase differences are developed. Perforated superstrate is loaded on the top of conventional metallic patch-based AMC unit-cells which contributes to oblique incidence stability up to 60°. Moreover, it results in a wide operational frequency range of 16.5–58 GHz under normal incidence. To satisfy the periodicity condition, an appropriate number of proposed AMC unit-cells are considered as a super-cell. Then for the first time, the type and size of super-cells are optimized simultaneously. In consequence, maximum RCS reduction with a very uniformed scattered pattern is achieved. The superiority of the new arrangement over conventional coding arrangements is investigated for both monostatic and bistatic RCS results. It is shown that new structure results in a wider bandwidth, greater RCS reduction level and more uniformed scattered patterns. The proposed surface exhibits a very broadband of 111.5% for −10 dB normalized RCS reduction under normal incidence. A prototype is fabricated, and the experimental results showed promising agreement with the simulated ones.