A Fast Technique to Estimate the Mutual Coupling Coefficients From the Transmitting Characteristics of an Isolated Element

This letter presents a fast technique to estimate the mutual coupling between the elements in an antenna array from the transmitting characteristics of an isolated element. This approximation is obtained from the transmitting coefficients in terms of spherical waves in reciprocal antennas by using the translational addition theorems. The external coupling is interpreted as a contribution of all different orders of reflection between the array elements where the first order of coupling interactions does not depend on the scattering characteristics of the elements. This method is validated through the estimation of the mutual coupling between different elements compared to the full-wave response.