Abstract
A high order mode electromagnetic wave coupler of a proportionally allocated bypassing device and its coupling method are disclosed. A bypassing device, which is a Y-configured waveguide and is designed to be a first or higher order bypassing mode, is utilized to bypass a target electromagnetic wave into proportionally allocated symmetric electromagnetic waves. The proportional electromagnetic waves are transmitted to a main waveguide by waveguide structures such that the electromagnetic waves in the main waveguide are transformed into polarized high order modes. An example based on this principle is to transform a TE10 mode electromagnetic wave in a rectangular waveguide into a TE01 mode electromagnetic wave in a cylindrical waveguide. The method can be extended for other mode transformation for other high order modes and other waveguides in different shapes. The coupling method of the present coupler consists of an electromagnetic wave bypassing stage and a mode transformation stage. The electromagnetic wages are divided symmetrically into even portions by a proportionally allocated bypassing device, and then are transformed into high order modes by a mode transformation device such that the coupler and its coupling method are of high transformation efficiency, high mode purity, high bandwidth, and easy processing.