研究了一种新型的过模圆转弯波导，可实现圆波导TM01模的转弯传输。介绍了这种过模圆转弯波导的基本原理：即沿转弯平面插入一块金属板，将圆波导转换为两个半圆波导。圆波导TM01模在半圆波导中转换为半圆波导TE11模，经转弯传输后，重新将半圆波导TE11模转换为圆波导TM01模，从而实现圆波导TM01模的转弯传输。基于这一原理设计了一个中心频率为2.856 GHz、转弯45°的过模圆转弯波导，并进行了数值模拟和实验研究。实验结果表明：其转弯半径为123.7 mm，转弯半径较小；在中心频点2.856 GHz处，传输损耗约为0.247 dB，驻波系数为1.217；在2.75～2.95 GHz的频率范围内传输损耗小于0.53 dB，驻波系数小于1.34。

One novel overmode bend circular waveguide is designed and studied. The novel approach is as follows:the circular waveguide TM01 mode is converted to half-circular waveguide TE11 mode by inserting fins into the overmode bend circular waveguide along the plane of bend. After transmission by the bend, the half-circular waveguide TE11 mode is re-converted to the circular waveguide TM01 mode. An overmode bend circular waveguide of bend 45° for 2.856 GHz based on this principle is designed and optimized, as well as studied. The experiment results show that：at the center frequency of 2.856 GHz, the loss is about 0.247 dB and VSWR is 1.217. In the range of 2.75 GHz to 2.95 GHz, the loss and VSWR are below 0.53 dB and 1.34 respectively. Curvature radius of the overmode bend circular waveguide is 123.7 mm. Overmode bend circular waveguide has the advantages of small bend radius, simple structure and easy to machining, which can be applied to circular waveguide connection and bend in the feed network of high power microwave.