This paper deals with microstrip patch antennas of arbitrary shape, and techniques available for their analysis. It reviews the various approximate models utilized so far, and presents a rigorous mathematical approach, based on dyadic Green functions for stratified media. Integrals are obtained with integrands possessing both singularities and a divergent behavior at infinity: a numerical ... [Show full abstract] technique was set up for their integration. The antenna patch is cut up in rectangles, over which the surface currents are evaluated by a moment method. The antenna's input impedance is computed and compared with measured values.