Slotted parallel plate waveguide coupled to a dielectric loaded grounded strip

The radiation from a slotted parallel plate waveguide coupled to a conducting strip grounded to the upper plate of the waveguide is considered. The strip (shield) is loaded by a dielectric slab, which is in contact with the guide aperture. According to equivalence principle one shorts the guide aperture and places equivalent magnetic currents on opposite sides of the slot. Similarly, the conducting strip, which is parallel to the waveguide upper plate, is made continuous through infinity in both directions. Semi-infinite equivalent surface magnetic currents are placed on opposite sides of the semi-infinite slots. By this approach the structure is partitioned into several regions in which the fields are coupled by these slots. Continuity of tangential magnetic field at the slots is enforced to obtain a set of coupled integral equations in terms of slot electric fields. The infinite slots are truncated into finite width slots and the method of moment is used to solve the integral equations. Data are presented for the slot electric fields, far field and the reflection/transmission coefficients for a TEM wave excitation from within the waveguide.