Design and Implementation of a New Method for Producing Transverse OAM with Metamaterial Antenna Structure

Planar spiral orbital angular momentum (PSOAM) waves offer a promising solution to the inherent challenges of long-distance OAM-based communications. Traditional OAM-based communications face challenges such as low data rate, sensitivity to atmospheric turbulence, limited spatial multiplexing capacity, beam divergence due to central zero, and complex and large receiver structures. Although new techniques, such as novel vortex beam generation methods and advanced digital signal processing at the transmitter, and very complex and computationally intensive processing techniques at the receiver, beam focusing techniques, and the Partial Aperture Ratio method have shown improvements in addressing existing challenges, many limitations still persist. To overcome these limitations, this research proposes a new antenna structure based on metamaterials for generating PSOAM waves. A circular array antenna with an almost omnidirectional radiation pattern is designed to generate PSOAM waves with l = 3 and − 3 modes at 3 GHz. The antenna array consists of eight metamaterial antenna elements fed by an 8-port feeding network with a 45° phase difference between adjacent ports. The experimental results show the efficient generation and propagation of PSOAM waves. Remarkably, a signal reduction of 24 dB is observed when the receiver antenna mode is changed from 3 to − 3, which shows the potential of this architecture for robust long-range communication systems.