Research On Dual-Band Thz Bandpass Filter Based On Frequency Selective Surface

In recent years,the rapid development of various optoelectronic technologies has led to the application of terahertz technology in frontier fields such as basic research,medical imaging,high-speed communications,and military reconnaissance.Terahertz(THz)communication systems are no exception.Filters are an important part of the communication system,and their pros and cons play a decisive role in the application of technology.Therefore,it is important to study filter components that work in the THz frequency band which is of practical significance.Frequency Selective Surface(FSS)is a new type of artificial material.Due to its excellent frequency selection,it can be applied to implement the miniaturization of communication devices.Therefore,the study of THz filters based on FSS is of great importance in communication systems.Based on square ring and hexagonal ring FSS unit,this paper designs two dual bandpass filters that work in the 1THz?10TH.The three-layer cascade MEFSS structure is adopted.The upper and lower layers are double rings,and the middle layer is single ring,with a dielectric layer supporting the structure.The simulation software HFSS is used to analyze the influence of the structure size,and results show that the two filters are good at frequency selectivity.The THz filter based on square ring FSS can achieve dual passband filtering with center frequencies of 2.75 THz and 8.18 THz.The-1d B range of the low-frequency passband is2.28THz?3.22 THz,the-1d B bandwidth is 0.94 THz,and the fractional bandwidth is 34.2%,the maximum insertion loss is 0.04 d B;the-1d B range of the high-frequency passband is7.66THz?8.70 THz,the-1d B bandwidth is 1.04 THz,the fractional bandwidth is 12.7%,and the maximum insertion loss is 0.11 d B.The dual-frequency THz filter based on the regular hexagonal ring FSS can achieve passband filtering with a center frequency of 2.58 THz and 7.84 THz.The-1d B bandwidth of the low-frequency passband ranges from 2.28 THz to 2.88 THz,and the-1d B bandwidth is 0.60 THz.The fractional bandwidth is 23.2%,the maximum insertion loss is 0.03 d B;the-1d B range of the high-frequency passband is 7.24THz?8.44 THz,the-1d B bandwidth is1.20 THz,the fractional bandwidth is 15.3%,and the maximum insertion loss is 0.05 d B.Both filters have the edge of miniaturization,low loss,incident angle stability,and good frequency selectivity.Bandwidth can be adjusted according to requirements,which is believed to have important application value in future terahertz communication systems.