A collective UTD ray analysis for the radiation from conformal linear phased array antennas on large cylindrical surfaces

A collective Uniform Geometrical Theory of Diffraction (UTD) solution is developed for describing, in a simple fashion, the radiation from a periodic, finite but long, linear array of elemental antennas mounted conformally on a larger canonical circular cylinder geometry which is assumed to be a perfect electric conductor (PEC). This work is relevant to the prediction of the performance of large and conformal electronically scanned phased arrays in modern applications. The array elements can be placed along either the axial or the circumferential directions, respectively, on this canonical cylindrical platform. The elements are excited with constant magnitude and linear phase delay along the elements for scanning a beam within a conical region about the linear array distribution. The collective UTD radiation field of the entire array in the presence of the cylinder, when observed at any point which is not too close to the array, is vividly described here in terms of just three propagating rays; one such ray arrives to an external observation point from an appropriate point within the array interior, while the remaining arrive from each of the two ends of the linear array, respectively. The latter “collective” UTD ray description is in stark contrast to the conventional, inefficient, array “element by element” UTD field summation approach which lacks physical insight into the array radiation mechanisms. The future extensions of this work to treat quasi periodic arrays with realistic antenna elements having typical tapered array excitations, and also more general convex surfaces, will be briefly discussed in this paper.