Hybrid-mechanism metasurface-based wideband low-scattering antenna array.

In this paper, a direct scattering suppression method based on the hybrid radar cross section (RCS) reduction mechanism is applied to the design of a metasurface-based wideband low-RCS antenna array. The metasurface-based radiating patches are designed and optimized to exhibit a stable reflection phase gradient (RPG) under cross-polarized (cr-pol) incidence. For co-polarized (co-pol) incidence, extra metal strips are introduced to generate the 180° reflection phase difference in the low-frequency band for the scattering field cancellation and the uneven reflection phase distribution in the high-frequency band for scattered energy diffusion. Hence, the wideband low-scattering property can be ensured for both polarizations by appropriately arranging the aforementioned metasurface-based antenna units. A prototype of the proposed antenna array is fabricated and measured to verify the effectiveness of the proposed method. Measured results show that over 6 dB RCS reductions are achieved from 7.3-16.6 GHz and 6.7-16 GHz under co-pol and cr-pol normal incidence. Compared with reported linearly polarized antenna arrays without any additional RCS reduction structure, the proposed design realizes a significant enhancement of the RCS reduction bandwidth due to the integrated utilization of the hybrid RCS reduction mechanism.