Discrete real images of horizontal electric dipoles in microstrip structures

The Green's functions for microstrip structures are expressed in the spatial domain in terms of Sommerfeld integrals. The discrete complex image method is an efficient technique used to evaluate these integrals. The locations and amplitudes of these images are determined through complicated and computationally expensive procedures such as Prony's method or generalized pencil-of-function method. In this paper, a new set of real images is used to represent the Green's functions. The locations of these images are determined a priori, while the amplitudes are evaluated using a simple least square procedure. The technique is shown to yield excellent results for one- and two-layer microstrip structures.