Generalized formulation for resonance frequency of even polygonal microstrip antennas

A generalized expression has been derived for resonance frequency of polygonal microstrip antennas with even number of edges using modified magnetic wall method. Nature of polygonal resonators is analyzed with their equivalence to corresponding circumcircle resonators. Magnetic wall has been transformed into a dynamic function of vertex angle of polygons. The transformed magnetic wall includes the effect of non-uniform fringing around vertices and edges. A scheme to achieve the complete response of circular antennas from square and other polygonal antennas has also been presented. The proposed general expression accurately gives resonance frequency of even polygonal antennas at the fundamental frequency as well as higher harmonics. The proposed expression and theory agree with simulation and measured results of different polygonal antennas.