Frequency prediction of micro strip ring antennas using transmission line model

The radiation from microstrip patch antennas can be calculated from the equivalent magnetic current distributions around the edges of radiating patch. The magnetic current values can be obtained from the edge voltage (with respect to the ground plane) distributions. Thus the problem of microstrip antenna analysis reduces to that of finding the edge voltage distributions, for a given excitation and for a specified mode of the resonance of the patch. If one considers a rectangular microstrip patch operating in the TM10 (or any TMm0) mode, voltage distribution at the edges may be obtained by using a transmission line model. The transmission line equivalent of a TMm0 mode microstrip may be used to represent the network equivalents of various microstrip antenna configurations, and also for the patches described by the generalized curvilinear coordinate system, where the separation of variable method can be applied to the wave equation. This modelling approach has been used extensively in the analysis and design of microstrip antennas. However its applications are limited because of the inherent assumptions/ approximations in this approach for non-curvilinear coordinates[1].