An annular ring patch microstrip antenna was investigated numerically from the bandwidth aspect for a satellite link application. The desired portable antenna should occupy the physical volume of a typical briefcase and operate in the 400-500 MHz band. Numerical optimization is carried out using a commercially available computer package (EM, by Sonnet Software Inc.). The parameters optimized include the substrate thickness, feed location along the annular patch antenna and its relative dimensions. The software package was numerically validated for the rectangular patch geometries reported in the open literature. Experimental verification of this work is left to be carried out in the near future.