An E-Plane-Focused Triple-Layer Multibeam Luneburg Lens Antenna for 5G Millimeter-Wave Applications

A triple-layer multibeam Luneburg lens antenna (MLLA) at the millimeter-wave band is proposed. The proposed lens features a triple-layer all-dielectric cylindrical structure. Each layer features the same configuration, which is realized by hole drilling technology. Seven feed antennas are positioned on the periphery of the middle layer to perform multibeam radiation. The feed antennas are horizontally polarized, hence the MLLA is E-plane-focused. Except for focusing in the middle layer, the wavefront coming from the feed antennas can be also focused in the top and bottom layers. Therefore, the sidelobe level (SLL) in the H-plane of the triple-layer MLLA is reduced drastically when compared with a single-layer MLLA. The triple-layer MLLA is fabricated and tested, with a measured −10 dB impedance bandwidth of 24–34 GHz. The measured peak gain reaches 18.2 dBi at 28 GHz, while the beam scanning coverage is up to ±55°. The antenna is well developed for 5G millimeter-wave applications, with the advantages of low cost, light weight (only 32 g), enhanced gain, and multibeam function.