Study On Therahertz Substrated Integrated Waveguide Based On Wide Band Gap Semiconductor And Process

Terahertz(1THz=1024GHz)band is between the far infrared light and millimeter wave regimes in the electromagnetic wave spectrum,which has been a very advanced research field and has great strategic value.The terahertz circuits have come true in recent years,due to the continuous breakthrough of semiconductor technology,especially the realization of terahertz active devices based on wide bandgap semiconductor.While the propagation of terahertz wave in atmosphere or enclosed circuit structure is limited by the attenuation effect of polar components,the study on low loss and high performance terahertz transmission lines is needed.In all kinds of transmission structure,substrate integrated waveguide(SIW)is proposed in recent years and has a closed type structure.SIW not only inherits the characteristics of high quality factor,anti-radiation,anti-interference,but also has the advantages of easy integration,easy processing.It makes the research of terahertz substrate integrated waveguide based on wide band gap semiconductor has great significance.In this paper,the transmission characteristics of terahertz substrate integrated waveguide and microwave network theory are analyzed.Thus,the terahertz substrate integrated waveguide is realized by the existing silicon carbide(Si C)process.Based on the analysis of power divider and filter in the terahertz region,some new structures are proposed.The research contents are as follows:(1)Study on terahertz integrated waveguide.According to transmission line theory,the single-mode transmission characteristics of SIW in the 100 GHz to 200 GHz band are studied.In the case that the terahertz wavelength can be compared with the size of metallic hole and hole spacing,we analyzed the influence of the size,the distance and the shape of metallic hole on transmission performance of terahertz integrated waveguide.In order to solve the problems of testing SIW in terahertz band and realizing seamless integration to planar circuit,several kinds of transfer structures of terahertz integrated waveguide to planar circuit are designed: transition of SIW to microstrip line and transition of SIW to coplanar waveguide(CPW).(2)Study on semiconductor process based on Si C: In order to achieve high performance of terahertz SIW on Si C,the material characteristics and semiconductor processing of Si C are studied.After several processes such as grinding,washing,etching,sputtering, electroplating etc,we realized a high performance terahertz SIW on Si C,which lays the foundation for the later design of terahertz passive devices based on substrate integrated waveguide structure.(3)Study on terahertz wave filter: In order to improve the frequency selectivity of the terahertz filter,a hybrid electromagnetic coupling four order filter and a dual-mode filter are designed based on the two port network in this paper.Hybrid electromagnetic coupling four order filter uses multi-cavity electromagnetic coupling mechanism to introduce two asymmetric transmission zeros out-of-band and improve the frequency selectivity.Dual mode filter uses multimode cavity theory and make the degenerate modes of high-order modes orthogonally coupled in cylindrical cavity.This structure not only improves the frequency selectivity,but also realizes the miniaturization of terahertz filter(4)Study on terahertz substrate integrated waveguide power divider: Based on the three port network theory,the terahertz integrated waveguide power dividers of Y type and T type are studied.While the Y type terahertz power divider uses the inductive effect of the metallic hole to adjust the reflection wave and energy distribution of each port.The T type terahertz power divider utilizes the structure and process characteristics of SIW to improve the matching characteristics of the port,and introduces resistive loss and radiation loss by changing the hole spacing and hole resistivity.