Integrated Low RCS Reflectarray Antenna Based on Multimode Metasurface

To further enhance the integration of the antenna while maintaining its high gain and low radar cross section (RCS) characteristics, an integrated low RCS reflectarray antenna based on a multimode metasurface is proposed in this letter. The unit consists of a diagonally placed rectangular metal patch with three cut slots and a metal plate. The central slot, aligned along the long edges, is designed to integrate the functions of in-band copolarized reflection and out-of-band cross-polarized reflection. The bent slots at the ends serve to broaden the bandwidth of the co-polarized reflection and to modulate the reflection phase by adjusting their length. Prototypes of 16×16 reflectarray antenna are then designed by premeditatedly arranging of the units and their mirror structures. Simulated and measured results demonstrate that the broadside gain reaches 24.8 dBi at 7.8 GHz with the aperture efficiency of 34.9%. Furthermore, the 10-dB RCS reduction band spans from 4.27 to 13.5 GHz (104%), and observed in the bands of 4.2∼6.6 GHz (44.4%) and 9.4∼11.9 GHz (23.5%), for incident waves polarized parallel or perpendicular to the antenna polarization.