Analysis of waveguide multi-ports discontinuities by the Helmholtz weak form and mode expansion

An analysis of waveguide multi-port discontinuities is presented using an approach combining the mode expansion method and finite element method, which is based on the weak form of the Helmholtz equation. The expression of the weak form of the Helmholtz equation containing anisotropic media is derived, and its reduced form without anisotropic media is also given. Mode expansion other than perfectly matched layer (PML) is used to truncate the computing space of finite elements. Junction circulators loaded with different shape ferrite posts and power dividers are studied as examples. The calculation results of the scattering parameters of these structures are shown and compared respectively to those in the literature and experiments. Consistency has been observed and their validity is verified.