A correction to a cavity model for thin and multiple layer metalizations

A useful technique for the analysis of microstrip antenna is provided by the cavity model (Lo and Lee, 1988 and Lo et al., 1979). Unfortunately, the cavity model as it currently exists assumes that the radiating patch and ground plane metalizations are either many skin depths thick or thin enough that a DC current distribution may be employed. Low frequency or integrated microstrip antennas may have metalizations that are less than a skin depth thick or consisting of multiple layers of different metals. In order to accurately predict the performance of these microstrip antennas with the cavity model, the calculation of the conductor loss will have to include the effect of thin or multiple layer metalizations. This may be accomplished with the spectral domain method (Vilcot and Tedjini, 1993 and Itoh, 1989), however, the result is not easily applicable to the cavity model. This paper is concerned with the application of the cavity model for the analysis of microstrip antennas with metalizations that are less than a skin depth thick, or consist of multiple layers of different metals.