Admittance-wall model of rectangular microstrip antennas using an eigenfunction expansion of the one-dimensional Green´s function

Preliminary results of the analysis of thin microstrip antennas using a complex admittance-wall boundary condition are presented. The wall admittance is obtained from the fields produced by currents on the microstrip patch and its image. The corresponding boundary value problem is solved using an eigenfunction expansion of the one-dimensional Green´s function showing the complex resonant frequencies explicitly. Features of the model include good physical insight, accuracy, no need to introduce edge extensions, and the advantage of a simple formula giving at once the input impedance over the whole frequency range of a mode and for a range of possible locations of the feed.<>