Design and Equivalent Circuit Model Extraction of a Frequency Selective Surface-Based Broadband Filter for Terahertz Applications

In this paper, a frequency selective surface-based band pass filter is proposed in terahertz regime. The proposed filter provides a great performance in pass band and out-of-band regions. A fractional bandwidth of 60% around the central frequency of 0.4 THz is achieved whereas a high transmission magnitude with an acceptable flatness is obtained in comparison to previous reports. Additionally, an equivalent circuit model is extracted for the proposed filter. A comparison between simulation results and those obtained using proposed circuit model shows a good agreement. Moreover, the sensitivity of the proposed filter with respect to the incident wave angle is investigated in the range of 0 to 60̊. It is demonstrated that the performance of the designed filter is acceptable for various incident angles in the mentioned range. Also, the effects of altering different geometrical parameters are investigated and justified based on the equivalent circuit model.