Research On Frequency Selective Surface Based On Resistance And Capacitance Loading

S band is the frequency often used in warning radar and tracking radar.In this paper,the theoretical experiment of frequency selective surface in S band based on load is presented and two schemes of resistive and capacitive loads are designed.The effect of load on the resonant frequency is explored and the advantages and disadvantages of the two schemes are compared,also the frequency selective surface specimens based on resistive load are fabricated and tested as well.In conclusion,the feasibility of the resistive load is verified.Lastly some other active implementations are also explored::1.Designed three frequency selective surface structures in S band,noted as: the square slot ring structure,the cross slot ring structure,and the strip structure.All resonant frequencies are all set up to about 2.5GHz.In this chapter,the influence of various shape parameters on the frequency selective surface is investigated.Based on the research of resistive and capacitive loading,the results indicate that the band-pass structure of small resistive loading resonant frequency is significantly increased,while for large resistive loading,it only changes little;with the increase of the loading capacitance,the resonant frequency decreases.For the band-stop structure,small resistive loading decreases the resonant frequency significantly,while the large one changes little.With the increase of the value of the capacitance,the resonant frequency decrease.By comparing the angle of stability,it is concluded that the loading does not affect the stability of the angle.Finally,the advantages and disadvantages of the two methods are compared,and summarized the issues of the scheme selection which attention needs to be paid to.2.Based on resistive loading,two frequency selective surface specimens in S band are manufactured and tested.The results of the experiment showed that the transmission coefficient of the specimens is in good alignment with the simulation results.The specimens' resonant frequency can be increased to C band by loading.It shows that the scheme can achieve the purpose of changing the resonance frequency.3.The feasibility of using other ways to realize the active method is discussed The effect of using liquid crystal as a dielectric and changing the relative angle of adjacent elements on the performance of FSS is also investigated.The results of simulation showed that the resonant frequency of FSS decreases with the increase of dielectricconstant.With the increase of the folding angle,the resonant frequency decreases.This suggests that these two methods can also achieve the purpose of changing the FSS resonance frequency and are theoretically achievable.