有损金属圆波导中电磁波传输特性的研究

Propagation of electromagnetic wave in a lossy cylindrical waveguide

基于电磁模式的色散方程,研究了有损金属圆波导中电磁模式的传输问题.在考虑了损耗层厚度影响的情况下,得到了各模式传输常数的近似解析表达式,此式适用于截止频率附近.通过解析表达式和波导模式色散方程,对衰减常数和相位常数进行了大量数值计算,得到了它们随损耗层厚度、频率以及损耗层电导率的变化规律,两种方法所获得的结果有较好的一致性.研究表明,损耗强度和损耗层厚度的变化会改变波导中电磁模式的色散和简并特性,对于改善高功率回旋行波放大器中注波互作用带宽和模式竞争非常有益.

Based on the dispersion equation of electromagnetic mode, the propagation characteristics in a lossy cylindrical waveguide are studied. The analytic formula of propagation constant for all modes in the waveguide is presented, which includes the effects of the thickness of the lossy layer. A large uumber of numerical calculations using the analytic formula and the dispersion equation have been candied out on the relations of the attenuation and phase constant with wave frequency, thickness and conductivity of the lossy layer. The analytic calculation results are in good agreement with those of the dispersion equation. This research is useful for selecting appropriate distributed wall losses for the stable and wide-band operation of gyrotron traveling wave amplifiers.