Design And Simulation Of Terahertz Band-pass Filter Based On The Structures Of Frequency Selective Surface

THz filter, an important functional device in THz systems, is widely used incommunication system and detection system. Due to existence of the noise and otherfactors in the actual environment, in order to improve its overall performance theterahertz filter is needed to filter out the unwanted frequencies and noises. Soanalyzing the transmission characteristic of THz filters is quite important to improvethe performance of the THz communication system.The design of traditional THz filter requires a lot of computation, it is difficult toanalyze the complex cell model and cascade structure, so the filter performance isnot satisfactory. Based on the3D finite element method electromagnetic simulationsoftware HFSS THz filter is analyzed in qualitatively and quantitatively in GentaiSP24IXM server. This paper, firstly, studied filter characteristics of three basic insingle-layer, and then analyzed the transmission characteristics of the cascadestructure, thirdly designed three THz filters with new structures and all of them centerfrequencies are0.6THz.The main contents in this paper include the following three points:(1) Analyze frequency responses of THz filter based on the traditional structuresuch as cross unit, Y shaped unit, circle unit of frequency by changing length, width,dielectric layer. The results show that the increase in cell size and loading of thedielectric layer reduce the resonant frequency and the length of arm hasmore influence than width on the resonant frequency.(2)According to the double-Y model structure another three kinds of structures:symmetric structures, asymmetric structure and diversity dielectric layer structure areresearched and summarize some experience of designing terahertz frequencyselective surface. The results show that compared with the single layer structuremodel, multi-cascade structure has wider bandwidth and better performance andasymmetric multilayer structure can complement its own filtering features andloading the base of dielectric layer between two FSS impacts the resonant frequency alot than loading on the upper and lower side(3) Design three kinds of THz band-pass filters using copper as the material arranged in square shape.a. The filter’s cell structure is cross with Y head. Its center frequency is0.6THz,the band-pass range is0.56-0.64THz with a3dB band width of0.08THz andinsertion loss of0.0423dB. The transmission coefficient is99.36%.b. The filter’s cell structure is hexagon with Y head. Its center frequency is0.6THz, the band-pass range is0.533-0.658THz with a3dB band width of0.125THzand insertion loss of0.71dB. The maximum transmission coefficient is99.59%.c. The filter’s cell structure is similar to double bows. Its center frequency is0.6THz, the band-pass range is0.563-0.643THz with a3dB band width of0.08THzand insertion loss of0.27dB. The maximum transmission coefficient is above94%.