Radiation admittance of an open-ended parallel plate metallic waveguide with exterior planar dielectric coating

A methodology is presented for the calculation of the radiation admittance of an open-ended, homogeneously filled, parallel plate metallic waveguide with exterior planar dielectric coating, operated at the fundamental (transverse electromagnetic wave) mode. The methodology relies on the definition of an auxiliary electromagnetic boundary value problem that is simple to solve using an integral equation approach. In order to provide for broadband calculation of the radiation admittance of the open-ended waveguide from DC to several tens of gigahertz, a loop-tree decomposition scheme is used in the method of moments solution of the resulting integral equation. A rational function-fitting process with passivity enforcement is used to generate a broadband, passive macromodel for the calculated radiation impedance. Such a macromodel is suitable for use as a local truncation boundary condition in the finite difference/finite element modeling of electromagnetic interactions in multilayered signal and power distribution networks encountered in printed circuit boards and packages.