Comparison of currents on upper and lower sides of patch conductor of microstrip antenna

In the analysis of a microstrip antenna (MSA) by the method of moments in the spectral domain (SD-MoM) (see Mosig, J.R., 1989), the patch conductor is normally assumed to be infinitely thin, and the total electric currents on the upper and lower sides of the patch conductor are derived. We derive the electric currents on the upper and lower sides of the patch conductor by SD-MoM taking consideration of the thickness of the patch conductor. Integral equations are derived from the boundary condition that the total tangential electric field vanishes on the upper and lower sides of the patch conductor. The total electric field is derived using Green´s functions in the spectral domain produced by the electric dipoles on the upper and lower sides of the patch conductor. In order to clarify the effects on the antenna of the currents on the upper and lower sides of the patch, the input impedances due to those currents are calculated.