ASYMPTOTIC ANALYSIS OF MUTUAL COUPLING IN CONCAVE CIRCULAR CYLINDRICAL ARRAYS .1. FAR-ZONE

This paper addresses the basis for the periodic structure ray method ( PSRM) for evaluating coupling coefficients in large arrays on concave surfaces. A canonical model of a concave array is analyzed. It consist s of an equispaced, stacked-ring array of open-ended rectangular waveg uides in a perfectly conducting concave circular cylindrical ground su rface. It is shown that in such an array the coupling coefficients may be evaluated as a superposition of a small number of periodic structu re ray contributions. A typical such contribution consists of a number of factors, each indicative of a specific physical event that takes p lace during the ray travel from the transmitting to the receiving elem ent. The ray expressions are presented in an invariant form, independe nt of element type, lattice, and shape of the array surface. This form admits a straightforward GTD generalization of the periodic structure ray formalism to arrays on concave surfaces with variable curvature.