Optimization of array performance subject to multiple power pattern constraints

Many antenna array performance indices can be expressed as ratios of Hermitian quadratic forms in the element excitation coefficients. A method is presented for the optimization of such performance indices with respect to the excitation coefficients and subject to multiple nonzero constraints on the array power pattern. The optimum excitation vector is shown to satisfy a characteristic equation with quadratic constraints. The solution of this equation is reduced to another quadratic form optimization problem for which solution techniques exist. Intended for applications involving power pattern constraints, the method of this communication avoids the penalty generally incurred by the alternative approach of arbitrarily specifying radiation pattern phase and using existing results on performance index optimization with radiation pattern constraints. As an example the method is applied to the problem of reducing the sidelobes of a circular array under a constraint on the main-lobe beamwidth of the power pattern.