Ultra-Wideband Vortex Wave Array Based on Vivaldi Antenna Elements

The ultra wideband (UWB) vortex wave antenna carrying with orbital angular momentum (OAM) usually has low mode purity and complex structures. For this reason, the Vivaldi antennas with single gradient side-line are used as the array element to constructs an UWB OAM slot array with rotationally symmetric distribution and in-phase feeding. In this case, vortex waves with a relative bandwidth of 72% is achieved, and the average mode purity in band reaches 55%, while maintaining good directional pattern bandwidth. Obviously, this antenna structure can be used for ultra wideband communications in OAM modes.