PATTERN SYNTHESIS FOR LARGE PLANAR ANTENNA ARRAYS USING A MODIFIED ALTERNATING PROJECTION METHOD

Abstract

A pattern synthesis approach based on a modifled alternating projection method for large planar arrays is presented in this paper. In the alternating projection method, pattern synthesis problem is considered as flnding the intersection between two sets: the speciflcation set and the feasible set. The former contains all the patterns that want to be obtained, while the latter contains all the patterns that can be realized. An element belongs to both sets is a solution to the problem. In this paper, a modifled projection operator which varies with the iteration number is introduced because the conventional alternating projection method is known to sufier from low convergence rate and/or trapping on local optimum depending on the starting point. When the planar array has a nonuniform element layout, the unequally spaced elements are interpolated into virtual uniform elements with an interpolation of the least square sense. Then the synthesis problem is converted to the problem of a uniform array. Finally, several examples are presented to validate the advantages of the proposed method. Results show that the modifled method is fast and obtains better results than the conventional one.