Novel OAM Antenna Based on Circular SIW Resonant Cavity

In a communication system, orbital angular momentum (OAM) serves as a means for multichannel transmission, enhancing both transmission capacity and communication speed. A novel approach by integrating eight “L”-shaped slots as disturbance elements is proposed in this paper. The circular arrangement induces a phase difference across the antenna's surface, effectively replacing the need for a phase-controlled array. Each disturbance element functions akin to an array element, generating continuous phase-differing electromagnetic waves at an azimuthal angle. The antenna is designed with a single port, enabling the formation of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> = −1 mode, thereby significantly simplifying the OAM generation device. By leveraging a substrate integrated waveguide (SIW) the antenna's footprint and cost are substantially reduced. Within the 22.7 GHz to 25.5 GHz frequency band, the antenna exhibits remarkable performance metrics: the modal purity of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> = −1 mode can reach over 95%, with a gain of over 8.2 dBi and a null depth of less than 40 dB. Additionally, it features a low profile, low cost, and high purity across a wide bandwidth, providing an ideal choice for wireless communication and radar technology.