Image series analysis of broadwall longitudinal slot coupler between parallel waveguides

A longitudinal coupling slot between parallel rectangular waveguides has been analysed by considering the infinite set of its images in waveguide walls. The internal admittance required for matching the tangential magnetic field is derived using the recently developed closed form point dipole and double dipole approximations alongwith Shanks´ transformation for evaluating the mutual admittances between images. The proposed general technique applicable for arbitrarily inclined slots is demonstrated using longitudinal broadwall slot coupler in parallel waveguides and shows good agreement with results from other techniques and experiment.