| In this thesis,it is studied how to widen the 3-d B axial ratio beamwidth of a single-layer square microstrip patch antenna.Based on the original performance of a square microstrip patch antenna,shorting pin loading technology and branch extension strategy are applied to increase the vertical displacement current between the patch and the floor,thus increasing the radiation intensity and the antenna gain in the main polarization direction of the model to widen the 3-d B axial ratio beamwidth.According to the inherent properties of the microstrip antenna's narrow bandwidth,additional parasitic patch technology is used to increase the impedance bandwidth of the improved model based on the coupled resonance theory of microstrip patches.Firstly,to achieve high-purity circular polarized waves,the latest research results of 3-d B axial ratio beamwidth technologies at home and abroad were collected and consolidated.The shorting pin technology is introduced into the field of widening the axial ratio beamwidth of the square microstrip antenna.Secondly,this thesis details the basic theory of microstrip antenna radiation and design for the follow-up study,and discuss the resonance characteristics of the microstrip antenna patches and the basic theory of the loading shorting pin technology emphasically.Thirdly,to achieve the circular polarization characteristics,the double-fed point single-layer square microstrip patch antenna is studied in this thesis.The influence of various parameters of the antenna on the electrical parameters and radiation characteristics of the antenna is discussed further.Based on the theory of coupling resonance characteristics between microstrip patches,additional parasitic patch technology to widen the bandwidth of microstrip patch antenna is applied,modeling dual-layer microstrip antenna.In order to widen the 3-d B axial ratio beamwidth of the square microstrip antenna,a technology of loading shorting pin is applied to the double-fed monolayer square microstrip patch antenna,and the applicability of the loading shorting pin technology in square microstrip patch antenna is studied.So the characteristics of wide-angle axial ratio and impedance bandwidth of a double-layer microstrip patch antenna loaded with shorting pins are studied.The results show that there is a contradiction between the wide-angle axial ratio characteristic and the impedance bandwidth characteristic of the double-layer microstrip patch antenna loaded with shorting pins.Based on the single-layer microstrip antenna with the shorting pin,the branch extension technology is proposed to realize the best overall performance of the dual-layer patch antenna.By modeling,HFSS simulating and analying antenna experimental data,the scheme is verified,and the influence of each parameter on the performance of the antenna is studied.Further,the parameters of double-layer square microstrip antenna with extended branch are optimized to realize the impedance bandwidth and wide-angle axial ratio.The results of the basic double-layer square microstrip antenna,the double-layer square microstrip antenna loaded with shorting pins,and the double-layer square microstrip antenna with extended branch are compared in this thesis,which shows the feasibility of the proposed methods.Finally,to meet the actual requirements,a feed network is applied to the antenna.Firstly,according to the demand for position and performance of the feed point of the antenna,a feed network is designed.Secondly,the amplitude,the phase and isolation of output ports are analyzed and optimized.Finally,connect the power divider with the antenna,a square-polarized microstrip antenna with wide axial ratio beam is given. |
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