Performance of a protruding-dielectric waveguide element in a phased array

A solution for the active array reflection coefficient in a two-dimensional array of parallel-plate-guide fed protruding-dielectric elements is presented. Analysis for this class of elements is not available in the literature. Element pattern nulls are found as in the case of dielectric-slab-covered arrays. The resonance mechanisms are also shown to be similar. Bandwidth properties of this array are briefly considered. A good agreement with experiments on two small arrays is found. Departures from infinite array theory, which take the form of a ripple on the flat portion of the element patterns and dips beyond the grating lobe angle, are shown to result from the finiteness of the arrays. These edge effects may be interpreted as arising from the interference between the "space wave," i.e., the infinite array element pattern and the fields radiated by the sources induced at the array edges by a wave traveling along the array face.