Research On Wideband Circularly Polarized And Multi-beam Millimeter-wave Antenna Array

Millimeter wave frequency band can not only effectively solve the problem of the shortage of spectrum resources in the current microwave frequency wireless communication system,but also make ultra-high-rate wireless communication technology possible.As an indispensable part of the millimeter wave wireless communication system,the design of various millimeter wave antennas and antenna arrays has become an important factor restricting the development of the entire wireless communication system.This article focuses on the design of millimeter wave antenna arrays in different scenarios.The specific research contents are as follows:Firstly,a millimeter-wave circular-polarized staircase curl antenna array with 2:1 bandwidth is proposed for the fifth-generation applications.The key antenna parameters for achieving 2:1 bandwidth have been investigated.Accordingly,benefiting from the tapered matching transformer,a single-layered full-corporate microstrip feeding network is constructed.For demonstration,an 8×8 staircase curl antenna array is designed on three-layer PCB laminates.The measured and simulated results are in good agreement.The measured ones show impedance bandwidth of 73.8%,AR bandwidth of 53.6%,and peak gain up to 18.7 dBic.It demonstrates a promising candidate for 5G mmW wireless system.Next,a novel technique to enhance the coverage of the broadband high-gain millimeter-wave antenna is proposed for Unmanned Aerial Vehicle(UAV)communications.This technique enables antenna to radiate two isolated beams with different tilted angles,which can effectively increase the UAV coverage without enlarging the antenna size or degrading radiation efficiency.For demonstration,an 8×8 antenna array is designed with 18 beams covering±28° seamless 2D plane over 57-64 GHz.The size of the proposed array is smaller than that of a standard A4 page,which is suitable for UAV-mounted mobile base station.Finally,a monopulse antenna with a combination of metal waveguide feed and dielectric radiation array is proposed.The antenna structure is composed of three parts:sum-difference network,double-layer feed network and radiation array.The feed part is designed with metal waveguide to reduce dielectric loss.By etching the radiation gap on the dielectric substrate,the radiation array is embedded in the feed network.The measured peak gain is up to 38 dB,the sidelobe level is lower than-20 dB thanks to the Taylor synthesis.In addition,the zero depth is lower than-16 dB,which can provide a good resolution for the target tracking application of monopulse antenna.