Broadband Low-RCS and High-Gain Microstrip Antenna Based on Concentric Ring-Type Metasurface

A novel integration strategy of microstrip antenna and metasurface is proposed to achieve low-radar cross section (RCS) and improved radiation performance simultaneously. Aimed at the applications in stealth cylindrical carrier, the antenna has a circular configuration, and the metasurface cells are closely arranged around the radiation patch in a concentric ring-type manner. Moreover, the mode analysis method is fully used to analyze the antenna's working mechanism and guide the optimization process. Owing to the addition of metallic vias, the original quasi-TM
₃₀
mode is altered to three series-TM
₁₀
modes and thus enhanced gain is achieved. Interestingly, the addition of vias also generates a new resonance which widen the antenna's impedance bandwidth. In another aspect, both in-band and out-of-band RCS reductions are obtained simultaneously. Finally, two prototypes are fabricated to validate the proposed design strategy. Good agreements between measurements and simulations are obtained. Measured results show that the gain of the proposed antenna is at least 3 dB higher than the conventional antenna in the entire operating band, and obvious RCS reduction is achieved from 4.0 to 8.5 GHz concurrently.