A New Design Approach for CMT-based Low RCS Metasurface and Antenna

In this paper, we apply the reverse thinking of prioritizing the low scattering performance over the radiation performance and propose a low radar cross section (RCS) metasurface array based on characteristic mode theory (CMT). Two types of patches were designed, circular patches with rectangular holes and cross patches, which are combined into two subarrays. The two subarrays are arranged into a checkerboard pattern array, so that the reflected fields generated in different regions on the metasurface aperture surface have the characteristics of equal amplitude and opposite phase, thus achieving the passive cancellation effect in a certain angular domain and frequency band. Then, an appropriate feed structure is integrated to enable the metasurface array to produce effective radiation. The method is clear and easy to realize, which greatly reduces the RCS of the whole array and the integrated antenna has good radiation performance. The simulation results show that the microstrip antenna operates in the frequency band covering from 8.1 to 9.3GHz, and a monostable RCS reduction of more than 10dB is achieved in the frequency band from 6GHz to 25GHz (with a relative bandwidth of 126.7%). The antenna achieves a peak gain of 9.6dBi. The antenna operates in the X-band, which is easy to fabricate and low-cost. It can be applied to radar systems and stealth platforms and other related fields.