Wideband Beam-Steering Flat Dielectric Lens Antenna for 5G Communications

A compact cylindrical-shaped flat dielectric lens (FDL) antenna, partially sandwiched within a parallel-plate waveguide (PPW), is presented. The design elegantly combines uniform FDL functionality within a PPW with a wideband rectangular waveguide-based feed network, resulting in a streamlined, highly manufacturable design suited for commercial beam-steering applications. In the feed network, an array of probe-fed rectangular waveguides, each accompanied by a symmetric E-plane step discontinuity and a partial-height conducting post, is employed to enable the launch of multiple beams over a wide operating frequency band. The lens design follows the procedure of partially sandwiching the cylindrical uniform dielectric between parallel conducting plates, allowing the dielectric extension beyond the plates to improve free-space matching and acting as a dielectric rod antenna to enhance directivity. The overall radiation performance of the antenna versus the feed network positions along the focal length of the FDL is precisely optimized through the use of the ray-tracing technique and genetic algorithm. This synergy yields a streamlined and highly manufacturable architecture specifically tailored to meet the demanding requirements of commercial beam-steering applications. The proposed FDL antenna with a nine-element feed network is designed to achieve azimuthal beam steering between ±33°. The results show that the gain remains almost constant within this range, with nearly 0.1 dB measured fluctuation. To validate the performance, the proposed FDL antenna is fabricated and measured. The measurements agree with the simulation results, demonstrating a wide operational bandwidth of 50% spanning from 24 to 40 GHz with a stable beam-steering capability. The antenna maintains consistent radiation characteristics throughout the operating range, with sidelobe levels below −15 dB and a peak gain of 16.7 dBi at the central frequency of 32 GHz. These features make the antenna suitable for various applications, ranging from 5G communications to radar systems.