Sensitivity of microstrip antennas to admittance boundary variations

The analysis of microstrip antennas is greatly simplified by a technique which separates the interior fields of the antenna from its exterior fields through the application of an admittance boundary condition at the periphery of the antenna. The goal of this investigation is to determine the accuracy to which one must obtain this "wall" admittance in order to predict operating parameters to a specified tolerance. For a typical microstrip antenna the "wall" admittance must be known to within 4 percent to predict the operating frequency to 0.5 percent.