Reseach On THz Filters

Terahertz band is a broadband which hasn’t been maturely developed, and there are a few advantages of it, such as high transmit rate of data, good directivity, higher safety level, low scattering, higher transmittance and so on. Therefore, terahertz technology has great potential applications in the field of communication. Terahertz filter is one of the key components of THz communication systems, and the quality of the filter directly affects the quality and level of THz communication systems.From the traditional microwave filter design theory, this paper analyzes daul-band filters with cross-coupled, parallel and multimode cavity structures; focuses on the sensitivity of dimensional error which affects the performance of terahertz filter and the realizability of manufacture; explains the advantages of rectangular cavity filter compare with other filter structures; proposes a new parallel structure of THz dual-band filter with coupling iris; designs a multimode cavity structure THz dual-band filter and a coupling iris parallel structure THz dual-band filter, and analyze the performances of the two filters. Because of the mini-size of terahertz filter, there are higher requirements of processing, so we use a more advanced MEMS processing technology.in consideration of the error of the diaphragm’s thickness are greater than diaphragm’s steepness and width impacting on filter performance, this paper tries many ways to solve this problem, including changing the coupling structure, reducing the number of coupling diaphragm, thickening the coupling diaphragm. After simulation and optimization,the THz dual-band filter of this paper meets the design requireme nts with the performance: return loss better than-10 dB in the transmission bands of 235GHz-245 GHz, 295GHz-305 GHz,isolation at 270 GHz better than-60 dB.