Hankel transform domain analysis of dual-frequency stacked circular-disk and annular-ring microstrip antennas

A theoretical and numerical analysis of the dual-frequency stacked circular-disk and annular-ring microstrip antennas is discussed. The problem is formulated in the Hankel transform domain. First, the Green´s function is derived, relating the transformed electric surface currents on the patches and the transformed tangential electric field components on the substrates. Galerkin´s method is used with Parseval´s relation for Hankel transformation to solve for the resonant frequencies and the unknown currents. The far-zone radiation patterns are expressed in terms of the transforms of the currents. Numerical results obtained for the resonant frequencies and radiation patterns are found to be in excellent agreement with the experimental data available in the literature