Radiation modeling of miniature waveguide antennas using the finite element method

The radiation model for the aperture of an open-ended miniaturized waveguide is verified by the numerical finite element method focusing on the radiation and edge aspects of the aperture field. The comparison is made between the models, the numerical method, and the measurements. The study raises a question as to the applicability of Silver´s (1949) far-field formula. When the aperture field is evanescent, its far-field prediction requires a careful modeling considering the approximations of both the aperture field and the radiation formulas