The Research On Sub-millimeter Wave Fss Circular Polarization

Millimeter wave and sub-millimeter wave has important applications prospect inthe field of modern wireless communications and radar acquisition, and it makesever-increasing demands on transmission control of the electromagnetic wave in thisband.Line-circular polarization converter as an important transmission control functiondevices, has an important role in the development of application systems. Therefore,this paper designs a circular polarization which works center frequency is in351GHz.The main work in this thesis is as follows:Firstly, the FSS circular polarization which based split slot ring has beenstudied,Through simulation, the impacts on polarization efficiency that the relevantparameters of the circular polarization has has been studied.The results show that:thedifference of the slit length between the inner and outer ring is the key parameters todetermine the phase difference between the two out going TE and TM polarizedcomponents; The slit width of the ring primarily affects on the bandwidth of the circularpolarization,and the bandwidth will be wider if the slit is wider; the cellspacing is thekey parameters to determine the bandwidth of the circular polarization,the couplingbetween units will stronger if cellspacing is smaller,and the bandwidth will be wider.The circular polarization this paper researched which working in center frequency351GHz can make the phase difference to83.25degree,and less than3dB axial ratiobandwidth is12.9%.Then proposed a FSS circular polarization based split slot square ring.Thesimulation showed that the affect of the grating lobe has been reduced in square unit,andit also improve the phase difference which has been increased to89.67degree from83.25degree.The performance of the double layer FSS circular polarization has been studied bysimulation. Analysed the affect to polarization efficiency which from the parametersinclude the space between double layer,the dielectric-loaded and the angle of incidence.Optimizationed of the structure of a double square FSS circularly polarized,and the axial ratio of less than3dB bandwidth is22.85%.