Design Of Terahertz Cavity Filter And Layered Structure Cross Coupling Research

Generalized terahertz means electromagnetic wave between 0.1THz-10 THz, whose frequency is higher than millimeter wave and lower than far infrared. The main applications include radar, medical imaging, astronomy, non-destructive testing, security checks and many other fields. Therefore, to carry out terahertz devices and systems research has important significance. As a widely used passive microwave device, terahertz filter is a growing concern.This study focuses on terahertz filter circuit with micromechanical technology and the basic theory to complete the accurate theoretical design and the physical filter on the metal material production. The primary goal is to successfully develop the terahertz filter and enhance the performance on this basis.The main contents are as follows:1. Acquainting the micro-mechanical processes, includs domestic and foreign technology, such as SU-8 photoresist, silicon micromachining(MEMS), LIGA, deep reactive ion etching(DRIE), laser machining, etc., and then according to the actual situation to select the appropriate processing technology.2. Design of the direct coupling of two waveguide filters with center frequency of 300 GHz. Filter which is higher than 100 GHz is not too much at present, especially over 300 GHz.So the research of this article is very necessary and pioneering.Both filters are made of a rectangular waveguide structure with Chebyshev filter prototype. The design principle based on coupling and coupling coefficient matrix. One of the filters is a four-chamber comb structure with a center frequency of 300 GHz, a bandwidth of 10 GHz and a passband return loss which is greater than 20 dB, a insertion loss which is less than 0.1dB. And away from the center frequency of the stop band rejection at twice the bandwidth is 49 dB and 35 dBrespectively. Another one is three chambers E surface of the metal film structure with a center frequency of 300 GHz, a bandwidth of 10 GHz and a passband return loss which is greater than 20 dB, a insertion loss which is less than 0.1dB. And away from the center frequency of the stop band rejection at twice the bandwidth is 3dB and 17 dBrespectively.3. The design of the two cross-coupled waveguide filters have transmission zero. Due to the high frequency, the corresponding device size is very small. So the coupling structure of the filter is extremely sensitive to the size, leading to cross-coupling is very difficult. This paper is designed for the first time in the terahertz filter to achieve acrosscoupled. It has an extremely important significance.Both filters are CQ topology and fourth-order Chebyshev filter prototype. The design principle is based on coupling and coupling coefficient matrix. One of the filter is a four-chamber CQ rectangular waveguide structure. The main coupling offset is H surface structure and the cross-coupled resonator by electrically coupling between 1,4 realization. The filter is one that with a center frequency of 300 GHz, a bandwidth of 10 GHz and a passband return loss which is greater than 20 dB, a insertion loss which is less than 0.1d B. The restrain is greater than 60 dB at the transmission zero 290 GHz and 311 GHz. Another one is four-chamber CQ circular waveguide structure, the main coupling through the cylindrical sidewall open window to achieve cross-coupled resonator by electrically coupling between 1,4 implementation, test results show that the center frequency of 100 GHz, the bandwidth of 4GHz, passband Return loss greater than 20 dB, insertion loss less than 0.1dB, transmission zeros located at 96 GHz and 107 GHz, respectively rejection 64 dB and 83 d B.By studying the theory and techniques of terahertz filter circuit, successfully developed a 100 GHz and 300 GHz cross-coupled terahertz filter and directly coupled terahertz filter 300 GHz, the development of terahertz device has a certain role.