21简介 a) b) c) a) e 还E马 EE马 Fig.1.Examples of waveguide devices which can be efficiently modeled by Mode-Matching: a)bandpass filter;b)square to circular waveguide transformer;c)diplexer with low-pass and high-pass filters;d)dual-Mode filter with elliptical waveguides;e)ortho-mode transducer (OMT);f)5-channel manifold multiplexer. 2.1 简介