THz频段圆波导传输特性的特征方程分析法

针对THz频段采用金属电导率趋肤效应模型会引入传播常数误差的问题,提出了一种非理想导体圆波导传输特性的特征方程分析法.首先基于圆波导中的场方程及电磁场边界条件得到了关于传播常数的特征方程；其次在特征方程中采用非理想导体电导率的经典驰豫模型,通过数值求解得到了圆波导的传播常数.与采用变分法计算传播常数的结果相比,特征方程法可在全频段上精确表征圆波导的传输特性.仿真结果表明:与传统变分法相比,圆波导特征方程分析法得到的衰减常数相对误差在10 THz时可减小66％；与传统的金属电导率趋肤效应模型相比,特征方程分析法采用金属电导率经典弛豫效应模型得到的衰减常数相对误差在6 THz时可减小31％.

Characteristic Equation Method for Propagation Properties of Terahertz Wave in Circular Hollow Waveguide

For the error of propagation constants with adopting the classical skin-effect model for the conductivity of normal metals in Terahertz frequency,a general and rigorous characteristic equation formulation is proposed for the analysis of hollow metallic waveguide.The characteristic equation for propagation constants is derived in terms of the field components equations and the boundary conditions in the circular waveguide.The propagation constants are obtained with the numerical solutions of the characteristic equation with the classical relaxation-effect model for the conductivity.The proposed method improves the accuracy for the full-wave characterization of waveguide performance,compared with the classical microwave approach that is the variational method with the classical skin-effect model for the conductivity.A comparison with the traditional variational method shows that the relative error of attenuation constant from the proposed method is reduced about 66% at 10 THz.,while a comparison with the skin effect model for conductivity shows that the relative error of attenuation constant using characteristic equation method can be reduced by 31% at 6 THz with the classical relaxation model.