A Low-Loss Design of Bandpass Filter at the Terahertz Band

This letter demonstrates a terahertz (THz) bandpass filter with a center frequency of ~340 GHz, low insertion loss of ~ -0.6 dB, and bandwidth of ~5.3%. The diaphragm thickness is quantitatively analyzed to obtain accurate filter parameters based on equivalent circuit and diaphragm coupling in THz band for the first time, and the simulation results based on calculated filter parameters show that diaphragm thickness has great influence on the filter performance. The test results show a good agreement with the theoretical analysis and simulation results. Meanwhile, the relationship between fabrication error and insertion loss was discussed and a quantitative mathematical model is given. The filter also shows an excellent performance when compared with the performance of other filters from the current literature reports.