利用数值保角变换，研究内圆外矩同轴传输线内TEM 波的场结构，利用软件MATLAB、HFSS 绘制其场结构图，并给出特性阻抗的计算公式. 研究结论对于计算该传输线的衰减常数、了解其功率容量、考虑功率耦合及设计有关的有源器件具有一定的参考价值

The distribution of the TEM wave in a coaxial transmission line with circular - inner - conductor and regular - hexagon - outer - conductor is obtained by using numerical conformal mapping. The map of structure of electromagnetic field is plotted by using the software MATLAB and HFSS，and its characteristic impedance is calculated. Furthermore，its characteristic impedance is calculated. This research result has certain reference value to calculation of the decay constant of the transmission line，realization of its power capability，consideration of its power coupling and design of the related active device.