Analysis of a Rectangular Waveguide Transverse Slot using MoM and Image Method

A waveguide fed transverse slot has been analysed using the Method of Moments (MoM) formulation, wherein the internal admittance matrix elements have been evaluated from image theory and using the images of the slot due to waveguide walls. The contribution from all the images not in the same row as the slot has been evaluated using a closed-form expression and a rapidly converging series with negligible contribution. The contribution from the row containing the reference slot has been evaluated by adding the mutual admittance between a few images and the reference slot using some recently developed simple and accurate approximations. The formulation has been extended to transverse slots radiating between the baffles. The results calculated using this simple, efficient and intuitive method are in excellent agreement with other theoretical as well as measured results. The technique can be extended to other slot configurations such as an inclined slot and for other slot aperture distributions such as with an edge condition in configurations permitting image formation.