Research On High Performance Antenna Based On The Characteristic Mode Theory

With the rapid development of wireless communication technology,modern wireless communication system has put forward higher and higher requirements for the performance of antenna,such as broadband,miniaturization,high gain,easy integration and so on.Therefore,the design of high-performance antenna has become a research hotspot in the industry.In recent years,the theory of characteristic mode has been widely used in the analysis and design of various antennas.The characteristic mode theory has a clear physical concept.Using the different mode information obtained by the characteristic theory,it can describe the resonance and radiation characteristics of various shapes of antennas and scatterers,which is conducive to understanding and guiding the design of high-performance antennas.In this thesis,based on the study of the research status at home and abroad,according to the requirements of wireless communication system,high-performance antenna is designed based on the characteristic mode theory.The specific work is as follows:1.A 6×6 rectangular grid unit metasurface antenna is designed based on characteristic mode theory for multilayered medium.The process of using the characteristic mode theory to guide the design of the super surface antenna is explained in detail.Through the steps of mode characteristic analysis,feed structure design and mode optimization,the principle of broadband radiation is clearly explained,and the metasurface antenna with wide-band and high gain is realized.The super surface antenna has been processed and tested.Its center frequency is 6.6GHz,the relative bandwidth of-10 d B impedance is 30.2%,and the boresight gain is between 7.5d Bi-10.5d Bi.It can be used in the new-generation WI-FI 6 band coverage and LTE Io T communication.The performance meets the requirements of communication scenarios and has good practical application value.2.A VHF band antenna is designed based on classical characteristic mode theory.Based on the analysis of the characteristic mode theory,the mode with resonance characteristic is selected,and the distribution characteristic of the mode current is observed to feed at the right position.The design of miniaturized(0.11 ?×0.08 ?)and wideband(30MHz-88MHz)VHF band antenna is realized by introducing measures such as cutting off the gap,loading the lumped element optimization and combining with broadband matching network.The simulation results show that the VSWR of the antenna is less than 3.5 in the working frequency band of 30-88 MHz,meanwhile the VSWR is less than 2 in the frequency band of 31-86 MHz.The horizontal gain is between-10 d Bi and 0d Bi,which has good horizontal omnidirectional radiation characteristics and meets the design requirements.