Design And Application Of High Performance Frequency Selective Surface

Frequency selective surface(FSS)is a two-dimensional or three-dimensional periodic metal structure printed on the surface of a dielectric substrate.Its essence is a spatial filter,which has a selective reflection or transmission filtering effect on the electromagnetic waves incident to its surface,making the original transmission characteristics of electromagnetic waves change.The metal elements that make up the FSS are mainly divided into patch type and slot type,which will show the filtering characteristics of reflection and transmission to the electromagnetic wave respectively,therefore,according to different needs,different unit structures can be selected to achieve different filtering functions,making it play a great role in the military,detection,civil technology and electromagnetic fields.In this paper,the working principle of FSS is studied,and its research hotspots in recent years are analyzed and discussed,including the design of multi-band FSS,the design of miniaturized ultra-wideband bandstop FSS and its application in antennas,and the main research contents include the following parts:(1)A high performance multi-band FSS operating in the C/X band is designed.The unit is composed of three layers of metal resonant units using a multi-layer cascade method,where the top layer has the same metal unit as the bottom layer,the new square ring structure is adopted,the middle layer is a metal ring.Which can generate a low frequency passband and a high frequency second order passband with broadband characteristics in the band range of 5-12 GHz to meet the demand of multi-band communication.Meanwhile,the performance of the FSS is analyzed by CST.The simulation results show that the designed FSS has good flat-top characteristics and steep sideband characteristics,and the transmission coefficient curve between bands decreases sharply with good out-of-band suppression.(2)Design of a miniaturized ultra-wideband bandstop FSS.Firstly,combining the traditional FSS design idea with metal square split-ring resonantor,a novel ultra-broadband band-stop FSS is proposed,which is capable of achieving a stopband bandwidth of 3.1-12.52 GHz,and the reflection phase decreases linearly in the band with good reflection performance.In order to further reduce the physical and electrical dimensions of the FSS cell and achieve a more compact structure,a novel miniaturized band-stop ultra-wideband FSS is designed by using the idea of double-layer loading.Compared with the previous structure,the size of FSS is nearly 30% smaller,which can be better integrated with small wireless communication systems to achieve miniaturization.(3)Design of FSS-based high-gain directional ultra-wideband antenna.In order to verify the reflection performance of the two designed ultra-wideband bandstop FSS,a planar monopole ultra-wideband antenna was designed as a feed source and integrated with the above two bandstop FSS to obtain two novel high-gain directional ultra-wideband antennas.The simulation results show that both FSS can reduce the backward radiated electromagnetic waves and enhance the directionality while maintaining the ultra-wideband,which increases the average gain of the antennas by nearly 3-4 d B.In addition,the miniaturized reflection array can achieve the size reduction with the same number of units,which has obvious advantages in size.