Uniform Circular Array Antenna for Dual‐Mode Orbital Angular Momentum Generation at 6 GHz

Orbital angular momentum (OAM) antennas have recently attracted attention for their potential to enhance communication capacity and and robustness against interference. However, most existing designs rely on complex multilayer feed structures. This work presents a compact, single‐layer, series‐fed dual‐mode OAM antenna composed of four patches arranged in a circular array with a 29 mm radius. The series‐feeding network can be excited from two ports to simultaneously generate the l = +1 and l = –1 modes. Measurements were performed in an anechoic chamber to obtain far‐field realized gain patterns and holographic phase distributions in the 6 GHz band. Two identical antennas were also tested in a transmit–receive configuration in a multipath environment using a two‐port vector network analyzer. The maximum realized gains are 3.65 dBi for l = +1 and 4.8 dBi for l = –1 at 6.1 GHz. The proposed single‐layer topology enables dual‐mode OAM generation and supports multimode multiplexing, enhancing spectral efficiency and suppressing interference without added hardware complexity.