Research Of Meta-surface Antenna Based On The Theory Of Characteristic Mode

From digital information to images,from voice to video,wireless systems need to transmit more data.Broadband performance and circular polarization performance with anti-multipath interference and no polarization mismatch loss are one of the key technologies for massive data transmission.In the previous antenna design,in order to achieve broadband,high gain and other performance,the premise is always to sacrifice complexity,manufacturing cost,size or other performance.How to apply new research methods to design antennas has always been a concern.In recent years,the characteristic mode theory has risen from the theoretical stage to practical applications,opening up new research methods for antenna researchers.In the absence of an excitation source,the characteristic mode theory explains the resonance and radiation performance of the antenna structure itself from the physical essence.In view of the convenience of characteristic mode theory analysis that does not require feeder and the predictability of antenna structure performance,this thesis uses characteristic mode theory to analyze single-layer metal,microstrip structure and metasurface structure separately,and proposes design on this basis an antenna with broadband performance and circular polarization performance is provided.The research work of the thesis is as follows:First of all,this paper proposes metasurface antenna with broadband,low profile and high gain performance based on the characteristic mode theory.The design is composed of three layers of metal and two layers of dielectric plates.In essence,the slot antenna is used as coupling excitation source to excite the metasurface structure.The target feature mode works effectively to achieve broadband performance.This antenna design analyzes the metasurface structure based on characteristic mode theory,and finally obtains broadband high-gain antenna with relative bandwidth of 37% and a gain of 7.1d B or more in the operating frequency band.Secondly,this paper analyzes the square cut corners metasurface element based on the characteristic mode theory,and predicts the physical properties of the metasurface structure through mode analysis,and finally achieves impedance matching at 5.39GHz?9.1GHz,and the relative bandwidth reaches 51.2%;the axial ratio is in Wideband circularly polarized antenna with 7.0GHz?8.58 GHz lower than 3d B and relative bandwidth of 20.28%,and the gain in the entire antenna working frequency band is above 7d B.A metasurface structure composed of 4×4 rectangular-like units is proposed.The characteristic mode analysis predicts that the structure has broadband circular polarization performance.Finally,the microstrip feeder is coupled with slot to excite the metasurface.The simulation results show that the impedance The matching frequency band covers 5.47GHz-9.31 GHz,the relative bandwidth reaches 51.9%,the 3d B axis ratio band covers 6.92GHz-8.38 GHz,and the relative bandwidth reaches 19.08%.Finally,this paper designs a new broadband circularly polarized metasurface antenna based on the characteristic mode theory.In this design,the characteristic mode theory is used to analyze the new metasurface structure to determine that the structure has achievable circular polarization performance.The influence of metasurface size on the antenna is analyzed,and the results show that the relative bandwidth of impedance matching reaches53.24%,and the relative bandwidth of axial ratio reaches 26.07%.