研究了一种通过改变波导内场分布的旋转对称性，可将高功率微波源输出的TEM模或TM01模转换为TE11模的径向线型模式变换器。介绍了该模式变换器的基本原理，即采用金属插板将同轴波导TEM模变换为4路90°扇形波导TE11模，各路扇形波导间所需的输出相位差通过将扇形波导转换为双层径向线传输来实现。基于这一原理，设计了一个中心频率为1.6 GHz的同轴TEM-TE11模式变换器，并进行了数值模拟计算，结果表明该模式变换器具有较高的功率容量，中心频率处反射系数为0.05，模式转换效率为99%，在1.52~1.68 GHz的频带范围内，模式转换效率大于90%。

A radial line mode converter is developed, which can convert TEM (or TM01) mode to TE11 mode by changing the azimuthal symmetry of field distribution in wavequide. The principle of the mode converter is as follows: the coaxial TEM mode is converted to 4-way 90°-sector-waveguide TE11 mode by setting fins into the coaxial waveguide; the output phase differences among the sector waveguides are realized by transforming the sector waveguide to two-layered radial line. A mode converter centered at 1.6 GHz based on this principle is designed and optimized. The calculated results show that it has high power handling capacity, with about 10% bandwidth (1.52 to 1.68 GHz) where the conversion efficiency exceeds 90% and the conversion efficiency and reflection are 99% and 0.05 respectively at the central frequency.