Investigations On Miniaturization Techniques And Designs Of Microwave Antennas

With the increasing development of 5G communication technology,communication systems have proposed stringent requirements for the performance of antennas.High efficiency,wide bandwidth,high gain,low profile and multi-functional have become the trend of antenna development.The booming mobile internet application markets need the reduction in the size and weight,extension in functionality of antenna system without compromising radiation performance to meet the mobility and functionality requirement in various application scenarios.Therefore,this paper aims at the limitations of the existing miniaturization method,such as complex structure,narrow bandwidth and insufficient miniaturization etc,and carries out indepth research on the miniaturization and multifunctional design of two typical antennas-linear end-fire antenna and metasurface antenna.The main contents of this paper can be summarized as below:1.Researches on low-profile end-fire antennas using capacitive loading parasitic stripa)Low-profile dipole antenna using capacitive loading parasitic strip.For dipole antenna,the effect of profile reduction on the performance of dipole antenna has been analyzed.A simple structure to realize low profile dipole antenna using capacitive loading parasitic strip has been first presented,and the mechanism of the phase control by the parasitic strip has been investigated.In addition,this low-profile method has been extended to the design of low-profile loop antenna,verifying the feasibility of this low-profile method in the design of different types of linear end-fire antennas.This research work has been published on IEEE Transactions on Antennas and Propagation.b)Compact Yagi–Uda antenna using parasitic interdigital strip.In order to meet the challenging requirement to achieve the compact physical scale along axial direction while maintain a wide bandwidth performance,a compact design of planar Yagi-Uda antenna by introducing a parasitic interdigital strip has been proposed.Benefit from this compact structure,a good balance between antenna profile and bandwidth has been achieved.This research work has been published on IEEE Antennas and Wireless Propagation Letters,and a patent has been applied.2.Researches on miniaturized metasurface unit cell using capacitive loading symmetric stripsa)Miniaturized low-profile metasurface antennas using capacitive loading symmetric strips.The basic property of metasurface unit cell and its advantages for antenna design has been investigated at first.Aiming at the disadvantage that the overall size of metasurface antenna is larger than conventional patch antenna in general,a novel miniaturized metasurface unit cell has been first proposed by introducing a pair of capacitive loading strip.Based on the square patch and corner truncated patch miniaturized metasurface unit cell,a miniaturize linearly polarized(LP)and a circularly polarized(CP)metasurface antenna using capacitive loading have been proposed.Prototype of these antennas have been fabricated and the measured results have verified that both antennas can exhibit good radiation performance within a relatively wide bandwidth,and this kind of miniaturized method can be applied for design and implementation of large-scale antenna array.This research work has been published on IEEE Transactions on Antennas and Propagation.b)Researches on applications of characteristic mode analysis(CMA)in designs of metasurface antenna.Based on CMA theory,the radiation mechanism of the proposed miniaturized LP and CP metasurface antenna has been revealed and explained clearly in terms of analyzing the intrinsic modal behaviors of metasurface.In addition,according to the current distributions of each characteristic modes,the structure dimensions and the locations of feeding structure have been further optimized.3.Researches on multi-functional antennas using switches and feeding networks loadinga)Compact pattern reconfigurable Yagi antenna using PIN diodes switches.Based on the low progile Yagi antenna using parasitic strip,the effect of changing electrical length of reflector on the performance of Yagi antenna has been analyzed.A compact Yagi antenna with four pairs of reflector and parasitic strip which controled by eight PIN diodes switch network was proposed to realize eight beams for azimuth omnidirectional coverage,and high gain performance can be realized for each beam.This research work has been published on IEEE Antennas and Wireless Propagation Letters and 2015 International Computational Conference on Electromagnetics(ICCEM 2015).b)Miniaturized dual polarizations metasurface antenna using cross-slot feeding network.In order to meet the requirements of 5G communication base station antennas,such as miniaturization,high gain and dual polarization.A miniaturized metasurface unit cell with duallayer structure has been proposed.Combined with cross-slot feeding network,a compact dualpolarized metasurface antenna with high efficiency and high isolation has been designed.The two different feeding ports of the antenna can generate horizontal and vertical polarization radiation respectively.Furthermore,this proposed dual-polarized metasurface antenna could be extended to a 1x4 dual-polarized metasurface antenna array,and this metasurface array can achieve a higher gain and better isolation while maintaining its low profile structure.