General technique to calculate subsectional edge expansion functions (SEEFs) for microstrip antennas in arbitrary multilayered structures

The technique of solving integral equations describing a microstrip antenna structure using the method of moments is well known and widely used. In this paper an efficient procedure is presented to determine subsectional edge expansion functions (SEEFs) containing the correct singularities of the currents at the edges of a rectangular patch located in an arbitrary multilayered structure. It is proven that the use of these SEEFs considerably improves the convergence of the calculated resonant frequency.