Higher-Order Quasi-OAM Generation Utilizing a Quasi-Circular Array Antenna

Orbital Angular Momentum (OAM) is a physical property of EM fields, which allows for the superposition of an infinite number of modes to exist on the same frequency carrier. However, as the number of OAM mode transmitted increases, so does the aperture size. Previous studies have shown that a QuasiCircular Array Antenna (QCA), where the annular aperture is truncated, is capable of producing a first-order Quasi-OAM noninteger mode. This paper investigates the capability of QCA apertures, in producing higher-order Quasi-OAM modes. The experimental results in free-space demonstrated herein, show that a QCA of six elements, is able to produce a non-integer Quasi-OAM mode of I = +1. 5, falling to the nearest integer mode I = +2 in the far-field.