Research And Application Of Three Dimensional Absorptive Frequency Selective Radome

Frequency selective surface is a variety of artificial electromagnetic surface,similar to the filter,the periodical structure in open space can be a role electromagnetic wave filtering,but as a kind of spatial filter,frequency selective surface itself is not on the electromagnetic wave absorption effect,but only for a specific frequency,polarization direction,and specific incident angle of wave has the frequency selective characteristics.Compared with the traditional two-dimensional periodic frequency selective surface,the three-dimensional structure can achieve better absorbing performance,angle stability and filtering characteristics,as well as wider absorption-band.Therefore,the study of three dimensional absorption frequency selective surface has attracted extensive attention.The main research work of this paper includes the following aspects:Firstly,this paper introduces the research significance of frequency selective surface and its development status,and at the same time systematically sorts out and expounds the theoretical knowledge of frequency selective surface.Then,it introduces the simple two-dimensional structure and analyzes its parameter rules,which provides support for the design of the following.Secondly,a band-pass absorbing frequency selective surface based on ferrite material is designed.This design uses a kind of absorbing silicone rubber with wide-band absorbing property and very thin thickness to realize wide-band absorbing wave,and at the same time,a cross shaped metal sheet is added on top of the absorbing silicone rubber to improve the impedance matching to air.On the other hand,a three-dimensional band-pass frequency selection structure is constructed by digging a circular metal gap in the absorbing silicone rubber and placing a metal film on the inner wall,thus realizing the band-pass characteristics.Next,a three-dimensional microwave absorbability frequency selective surface based on coupled slot structure is designed.This design utilized microstrip coupled gap structure and adopts microstrip line to coupling the electromagnetic field in the metal slot to the microstrip line for absorption by resistance.Compared with the method of directly load resistors onto metal gaps,this method greatly expands the absorption bandwidth.The measure results show that the microwave absorbing body with three-dimensional coupling microstrip line structure has stable performance under oblique incidence of electromagnetic wave,and can still show great performance under incidence angle of 40 degrees.Finally,in order to test the practical application effect of the three-dimensional microwave absorbing frequency selection surface based on the coupling slot structure,it was combined with the antenna,that is,as an antenna radome of linear polarization antenna,so as to reduce the RCS of the antenna and realize the stealth performance.In addition,the radome has little effect on the performance of antenna,which can be ignored.At the same time,the RCS of the antenna below radome is significantly reduced.