Floquet modal based approach for mutual coupling between elements in array environment

Presents a technique to determine the mutual impedance between elements in an array environment. The technique inherently includes the scattering effects of other neighboring elements on mutual impedance between any two particular elements. The active impedances of an element in an infinite array are determined by assuming that the array elements are excited with uniform amplitude and linear phase distributions in both directions. Such an excitation supports Floquet modes, so that we refer to the corresponding active impedance as the Floquet impedance. The Floquet impedance of an element is expressed in terms of self and mutual impedances. Using orthogonality and Fourier series expansion, it is shown that the self and mutual impedances can be obtained from the Floquet impedances. The technique essentially requires computation of Floquet impedances for a finite number of scan angles. For infinite patch arrays, the Floquet impedances can be determined using Floquet modal analysis and Galerkin´s method of moments. For multilayered patch arrays, it is more convenient to use a modular approach. The formulation presented then is programmed and the self and mutual impedances of patch elements in an array environment are computed and plotted.