Evaluation of the input impedance of a top-loaded monopole in a parallel-plate waveguide by the MoM/Green's function method

An accurate modeling of a top-hat monopole transition in a parallel-plate waveguide is performed using the method of moments/Green's function method. The selection of the appropriate source-field relationship to override divergence series is discussed in detail. Numerical results are given for the input impedance of a top-loaded coaxial transition. A mode-matching solution is used as a reference to validate the results.