ANTENNA ARRAY PATTERNS: ANALYSIS AND SYNTHESIS (PLANAR).

摘要

This dissertation deals with the analysis and synthesis of antenna array patterns. Simplified expressions for the directivity of planar arrays with various grids and boundaries are developed. These expressions are exact and economical to compute. From the directivity expressions, various limiting local and general behaviors are also deduced.; The simplified directivity expressions for a rectangular grid array of isotropic sources are used as part of a technique to maximize the peak directivity under side lobe constraints. By means of a projection matrix, the constrained maximization problem is converted into a problem of the unconstrained maximization of a quadratic function. For linear arrays, the peak directivity is maximized under side lobe level constraints. For square arrays, the peak directivity is maximized under specified ring side lobe constraints. The technique involves the use of the Baklanov transformation.; An antenna pattern synthesis technique is presented which permits the design of variety of planar antenna arrays. The phase distribution in the array is assumed to be known and the optimization of the array pattern is done by controlling only the positive real amplitude distribution. The technique is to minimize a scalar-valued performance measure, called the cost function, via the conjugate gradient method.; Last, techniques for designing planar arrays that produce flat-top main beams with specified levels of ring side lobes are developed. For rectangular boundary arrays, a Baklanov transformation is used, and for hexagonal boundary arrays, a new transformation is presented. Under these transformations, a single-variable polynomial. Since the pattern in every {dollar}phi{dollar}-cut is governed by the shape of this polynomial, the array pattern is almost rotationally symmetric. In both types of arrays, the collapsed distribution in one {dollar}phi{dollar}-cut of the pattern is assumed to be known; hence, the coefficients of the polynomial can be determined by equating this pattern with the polynomial. Since the coefficients of the polynomial are in general complex, the planar array pattern can be any shaped beam, including the flat-top beam considered in this dissertation.