An efficient hybrid UTD-MoM analysis of radiation/scattering from large truncated periodic arrays

A hybrid method is described which combines a previously developed UTD ray analysis for periodic structures with the conventional numerical MoM approach to efficiently analyze the radiation and scattering from electrically large finite arrays. The UTD, which constitutes an asymptotic high frequency ray solution, is extended to describe the fields of an entire large planar array (consisting of a very large number of elements) in terms of just a few rays which an relatively independent of the physical size of the truncated array for any given electrical spacing between the array elements. Thus, the few UTD rays, which emanate from specific interior and boundary (e.g. edge and corner) points of the truncated array, describe the entire array behavior very efficiently in a composite fashion; this is in contrast to the conventional rigorous element by element approach based on the MoM for including the mutual coupling in finite arrays that can become intractable for large arrays. The MoM is included in the present UTD approach to refine the assumed initial approximation for the field distribution over the array in this analysis. This numerical MoM based computation is typically confined only to the neighbourhood of the edge elements of the entire array thereby making these computations and hence the present hybrid method very efficient.