Ultrawideband Low-RCS Array Antenna Based on Double-Layer Polarization Conversion Metasurface

In this letter, a novel integration method of array antenna and polarization conversion metasurface (PCM) is proposed for wideband radar cross section (RCS) reduction. This method allows the design of low-RCS metasurface and conventional array antenna independently, and then directly combines them in a shared aperture. In this way, a compact metasurface array antenna is obtained, and low-RCS property is ensured first. Subsequently, the current analysis methodology is utilized to optimize the radiation performance, and a limited-removing strategy is proposed. This strategy not only improves the radiation performance but also keeps the low-RCS property. As proof of principle, a 2 x 2 array antenna is presented based on a double-layer PCM. Numerical results suggest that enhanced radiation performance and ultrawideband RCS reduction covering both in and out-of-band are achieved simultaneously, verifying the effectiveness of the proposed method. This method ensures low-RCS performance first and then modifies radiation performance, which essentially converts complex and time-consuming scattering optimization to mature radiation modification. Thus, it makes the design of a wideband low-RCS array antenna easier and faster.