This paper investigate the near-field interaction between the coupling slot and the radiating ones in a dielectric-covered waveguide slot array environment. This interaction can strongly affect the array aperture distribution and input match, mainly when each radiating guide contains few slots or the slot offsets are small. We propose a full-wave Method of Moments approach, taking also into account the waveguide wall thickness, to evaluate this interaction. The use of entire domain basis functions allows to get a small and well-conditioned linear system. The results presented in this paper show that the coupling due to high-order modes in the region of the junction can significantly modify the radiating slot voltage, mainly when the offset is small, and also the array input match, though to a lesser extent.
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