An orbital angular momentum vortex wave antenna with low in-band radar cross section and reduced divergence angle

In this article, an orbital angular momentum (OAM) vortex wave antenna with low radar cross section (RCS) and reduced divergence angle is proposed. The antenna is composed of four slot-coupled elements working from 7.5 to 8.0 GHz and fed by a phase shift network. OAM vortex wave with l = 1 is generated. In order to reduce the RCS and divergence angle simultaneously, complementary split-ring resonators (CSRRs) are designed and integrated to the antenna. The CSRRs can stop the transmission of surface wave and reflect the incident energy with phase canceling scheme. As a result, the RCS and divergence angle is reduced simultaneously.