Multifunctional Scattering Antenna Array Design for Orbital Angular Momentum Vortex Wave and RCS Reduction

In this paper, a multifunctional scattering antenna array has been proposed to generate orbital angular momentum (OAM) vortex scattering wave and meanwhile reduce antenna radar cross section (RCS). Theoretical analysis for integration of the RCS reduction and the OAM wave is given, and a circular antenna array composed of a dual polarized microstrip antenna and a tunable connection line network is designed. By adjusting the ON/OFF state of the PIN diodes embedded in the connection line network, the OAM scattering waves with the modes of $l=1$ and $l=2$ are independently generated, and accordingly in-band RCS reduction of a circular patch antenna with an increase of the antenna gain over 2 dB is achieved. A multifunctional prototype antenna array is fabricated and measured. Simulated and measured results demonstrate -10dB RCS reduction and the OAM scattering waves with the tunable modes in the frequency band of 9.37~9.8 GHz.