Research And Application Of Band-pass Millimeter-wave Frequency Selective Radome

Frequency selective surface(FSS)is a two-dimensional periodic array structure which has spatial filtering performance.By presenting transmission and reflection characteristics to incident electromagnetic waves,it achieves bandpass and bandstop performance.As a passive device,FSS is small in size and easy to integrate with other equipment.The working frequency band can be expanded from UHF band(300 MHz-3000 MHz)to R band(220 GHz-325 GHz).This paper designs bandpass FSS units that work in the millimeter wave,which have the profits of wide bandwidth and easy miniaturization.It has extensive future in national defense science and technology,civil communication technology.Firstly,this thesis focuses on the filtering mechanism and analysis methods of FSS.Generally,the slot type structure can achieve band pass characteristics,and the patch type structure can achieve band stop characteristics.The analysis methods of FSS are divided into vector method and scalar method.Among them,the vector method is represented by the finite element method,and the filtering performance of FSS is calculated through full-wave simulation.The scalar method is represented by the equivalent circuit method(ECM),which calculates the transmission characteristics of FSS from the perspective of the circuit.Secondly,based on the equivalent circuit model,combined with the full-wave simulation method,two single-band FSS units of the folding type and the “soil” font type,and two dual-band FSS units of the “H” type and the “arrow” type are designed.Further combining miniaturization methods and adding an axisymmetric structure to improve the angular stability and polarization stability of FSS.From the perspective of series and parallel resonant circuits,single-band and dual-band equivalent circuits that can achieve stable resonance are designed.Under the guidance of the circuit model,four FSS units are designed.The electromagnetic characteristics are calculated using the full-wave simulation software HFSS.Comparing the ECM with the full-wave emulation results,the outcomes coincide well between the two methods.It further illustrates the effectiveness of using equivalent circuit and full-wave simulation methods to analyze FSS.Finally,the integrated modeling of the FSS radome is realized,and the transmission and radiation characteristics of the system are further analyzed.Using Application Programming Interface(API)to call HFSS and MATLAB to operate jointly,it can accurately and quickly establish plane and curved FSS radome models.The trouble of low velocity and inefficiency of conventional modeling methods is settled.A four-unit microstrip patch antenna working in millimeter waves is designed as a feed source,and combines with FSS radome to realize integrated modeling.The full-wave simulation method is used to analyze the S parameters and radiation property of the system.It is proved that the designed FSS radome has good in-band passability.