Abstract: The full wave theory is used to analyse stacked microstrip patche anaenas. The mixed potential integral equation(MPIE) and the moment method are ed to obtain the current densities on the patches. In the calculation of Sommerfeld integrals(SI) of dyadic Green's functions, discrete complex image theory (DCIT) is used. It makes all computations more swift and precise. Some sample antennas were built up and the measurement data are compared with numerical results showing excellent agreement.