Abstract: A new Fourier's expansion-differential method for analyzing waveguides with arbitrary cross-section is presented, and a new type of truncated-circular waveguide is analyzed.The mode distribution is obtained.The method has advantages of direct-viewing expansion, simplicity and easy computation, therefore it is applicable to analyzing and calculating waveguide characteristics in microwave engineering.

Key words: truncated circular waveguide, waveguide with arbitrary cross-section, Fourier's expansion-differential method, microwave engineering application