通过本征方程研究了工作在太赫兹(THz)频段的高次模同轴谐振腔, 讨论了TMm,1,0模, TMm,2.0模与TMm,1,1模的谐振频率与腔体的几何参数之间的关系, 并给出了工作模式的选择依据。在此基础上, 提出了一种新型的0.3 THz TM10,1,0模同轴耦合腔链, 使用等效电路模型和CST-MWS软件对耦合腔链的色散特性、特征阻抗和电场分布等冷腔特性进行了分析和仿真, 并着重分析和总结了耦合腔链的几何参数对色散特性和特征阻抗的影响。研究结果表明：对于工作在THz频段的高次模同轴耦合腔链, 采用TM10,1,0模为工作模式是合理的选择; 工作于2π腔模的0.3 THz TM10,1,0模同轴耦合腔链具有较大的特征阻抗, 但模式间隔较小, 因此可将其应用于窄带太赫兹扩展互作用器件; 增大高次模耦合腔链的耦合槽张角是增大模式间隔的最佳途径。

In this paper, the eigen equation is utilized to study the high-order mode coaxial resonant cavity operating in the terahertz (THz) band, the cavity’s resonant frequencies of TMm,1,0 mode, TMm,2,0 mode and TMm,1,1 mode associating with the geometric parameters are discussed, and the evidence for selecting the operating mode is presented. On this foundation, a new type of 0.3 THz TM10,1,0 mode coaxial coupled cavity chain is proposed, analyzed by equivalent circuit and simulated by CST-MWS simulation software. Its properties of cold cavity such as dispersion characteristic, characteristic impedance and electric field pattern are presented. In addition, the effect of the geometric parameters on the dispersion characteristic and the characteristic impedance is analyzed and summarized emphatically. The results of the study indicate that, TM10,1,0 mode is a reasonable operating mode for the THz high-order mode coaxial coupled cavity chain. The 0.3 THz TM10,1,0 mode coaxial coupled cavity chain operating in the 2π cavity mode has a large characteristic impedance, but the frequency spacing between the modes is small, so it can be applied to a narrow-band terahertz extended interaction device. Increasing the angle of the coupling slot is the best way to increase the mode spacing.