Research And Design Of Broadband Pattern Reconfigurable Microstrip Antenna

With the rapid development of communication technology,the industry's performance requirements for antennas have become more stringent.Reconfigurable microstrip antennas can complete the corresponding reconstruction according to actual needs by changing some characteristic parameters,and have received extensive attention in recent years.The specific research content of reconfigurable microstrip antenna can be divided into the following three parts:?1?Analyze the antenna based on the characteristic mode theory,and design the broadband pattern reconfigurable microstrip antenna.By using FEKO software to compare the differences between the circular patch antennasTM₀₁,TM₀₂ andTM₁₂modes,it was found that the radiation modes of theTM₀₁ mode and theTM₀₂ mode are both cone beam modes.The operating frequency band ofTM₀₂ mode is slightly higher than that ofTM₀₁ mode.TheTM₁₂ mode radiation mode is an edge shot mode,and the intensity of the center area of the current distribution is large.According to the current distribution on the surface of the patch,an appropriate position is selected to reduce theTM₀₂ mode by slotting to achieve the effect of combining theTM₀₁ mode and theTM₀₂ mode,thereby realizing the widening of the frequency band of the cone beam radiation mode.Then,through a simple feeding network,the mode switching of the in-phase feeding and the reverse-phase feeding is realized,and then the switching of the antenna working mode is realized,and finally the pattern reconstruction effect is achieved.Through design optimization,the broadband reconfigurable antenna can achieve 33%of the operating bandwidth,and the operating frequency band is 5.7GHz?7.5GHz.The average gain of the antenna in the two modes in this band are:cone beam mode is 9.7d Bi The side shot mode is 11.3d Bi.?2?Use the characteristic pattern analysis to carry out multiple patterns switchable microstrip antenna design.Using FEKO to analyze the far-field radiation pattern and surface current distribution in different modes,slot the antenna to effectively control the different modes,and finally design a multi-mode switchable microstrip antenna.The antenna is fed through different ports,so that the circular patch antenna realizes three radiation modes of cone beam mode,side beam mode and two-way beam radiation mode respectively.On the basis of this antenna structure,the directional radiation pattern generated by the patch main modeTM₁₁ is used to realize the beam scanning effect of 15°?35°in the 3.7GHz?5.0GHz frequency band through the feed design,and the antenna gain here All are above 7d Bi,with an average gain of 7.49d Bi.?3?Design the beam scanning antenna based on the theoretical analysis method of the characteristic pattern.Optimize the design according to the broadband pattern tunable antenna designed in?1?.The main modeTM₁₁ mode of the circular patch antenna is adopted.By adjusting the feeding phase and excitation amplitude of the two feed ports,the antenna surface current distribution is changed,the antenna beam tilt angle is changed,and the radiation beam tilt angle is adjusted.In order to achieve the purpose of beam scanning,by changing the phase difference of the antenna feed,the antenna beam tilt angle can be changed from 0°to 26°,and the gain is more than 7d Bi.By changing the antenna feed excitation amplitude,the antenna beam tilt angle can be changed from 0°to 9°,and the antenna beam gain can reach as high as 9d Bi.In this paper,current analysis and characteristic pattern analysis are used to design the antenna,which optimizes the antenna performance and provides new ideas for the research of reconfigurable microstrip antennas.