A novel method for identifying complex zeros by searching the laplace-plane for local minima

In this paper, we develop a novel technique for computing the complex-conjugate zeros of rational transfer functions in partial fraction form, by searching the complex Laplace s-plane for the local minima of the determinant of a block matrix derived from the state-space equations. A higher resolution scan, in the vicinity of each local minima, may be used to increase precision of the zeros. This method can be applied to antennas to extract the zeros from the antenna response. One numerical example and one practical coax patch antenna example have been used to illustrate the efficiency and effectiveness of the proposed method.