Coupling of Waveguides through Large Apertures

A closed form expression for the equivalent network of a narrow transverse slot in the common broadwall between two waveguides is derived in terms of self-reaction and discontinuity in modal voltage. The coupling is expressed in terms of equivalent circuit parameter. A comparison between theoretical results with those obtained from the results of Levinson and Fredberg (for slot length > 0.4a, where a is the broad dimension of the waveguide), the results obtained from the formula of Sangster and the experimental results are presented.