An orbital angular momentum metasurface antenna with broadband radar cross section reduction

In this paper, a multifunctional metasurface antenna is proposed that can both generate orbital angular momentum (OAM) vortex waves with two different modes and reduce the radar cross section (RCS) in a broad band. By utilizing the generalized Snell's law, a phase -gradient matesurface is proposed as the coating of the antenna to realize a broadband RCS reduction in the range of 11.8 GHz-29 GHz. The two feeding networks for the slot array are designed to independently generate OAM waves with mode -1 and +1 in the range of 9.68 GHz-10.35 GHz. Based on the OAM spectral analysis, the purity of the generated OAM modes is also discussed. This proposed antenna is fabricated and measured, and the experimental results achieve a good agreement with those got from the simulation. It is also shown that our design exhibits superior performance over other existing antennas in terms of impedance bandwidth and RCS reduction bandwidth, which provides a sufficient approach for the OAM antenna with broadband low -RCS.