Abstract
Two-dimensional circuit is used to determine the resonant frequencies of the arbitrarily shaped, single-layer microstrip patch antennas. This circuit is based on the long transmission line model in the frequency domain. Derivation, analysis, and treatment of boundaries are given. Simple matrix form is obtained and the problem is reduced to an eigenvalue problem which is solved to get the required solution. The resonant frequencies of the resulting circuit are the required resonant frequencies of the patch antenna. Numerical results are given and are compared with the available analytical and experimental results reported by others.