Generation of OAM Waves Based on End-fire UCA with Dielectric Substrate Loaded

A compact wideband three-dimensional (3D) Uniform Circular Array (UCA) is proposed to generate dual-mode vortex waves, which consists of four miniaturized broadband end-fire antennas and loads some substrates. The array without loading works within two impedance frequency bands: 2.35 - 2.79 GHz and 3.09 - 3.35 GHz. Its stacked structures loading dielectric bricks would broaden bands. We investigate three loading strategies: antenna-substrate, substrate-antenna, and substrate-antenna-substrate structures. The antenna-substrate structure shifts the operating band to lower frequencies and still has two bands of 2.28 - 2.74 GHz and 3.09 - 3.34 GHz. The substrate-antenna structure yields a connective band of 2.33 - 3.21 GHz (32% bandwidth). The substrate-antenna-substrate structure yields the widest band of 2.28 - 3.29 GHz (36% bandwidth). Simulation results show that the last array could generate linear-polarization vortex waves of modes ‐1 and 1, and its gains at 2.88 GHz on the E- and H- planes are 4.29 and 1.17 dBi, respectively.