Mutual coupling in adaptive circular arrays

A simple technique that underlines the necessity of including mutual coupling (MC) effects during the adaptation process of an adaptive array is presented in this paper. This is demonstrated by illustrating the degradation in performance of an adaptive uniform circular array if the adaptive beamforming algorithm ignores MC effects. Simulation results show that by applying the complex excitation currents obtained at the convergence of the adaptive algorithm in ideal conditions, the resulting performance of the adaptive antenna in a real situation, where MC effects are involved, is very poor. As a practical example, a uniform circular array of half-wavelength dipoles was considered. The LMS algorithm was employed for the adaptive beamforming and the MC information was derived using the induced EMF method.