An improved full wave analysis for open circular microstrip structures

The circular microstrip patch has been analyzed by various methods. The cavity mode theory is valid only when the thickness of the substrate is relatively thin compared to the operating wavelength. The ordinary full-wave analysis may be employed for a thick substrate, but as the Green´s function is directly derived from boundary conditions by a complicated process, it will be more troublesome for multilayered substrates or patches. The improved full-wave method presented, which is based on the vector Hankel transform and the spectral domain immitance matrix approach, has the following attractive features: (1) the Green´s functions in the spectral domain can be derived by using the equivalent transmission line method; (2) only single integration are required; (3) only low-order matrix is dealt with; and (4) the inverse vector Hankel transform is not needed. Several numerical examples are compared with available experimental data.