Reduction of mutual coupling by near-field coupled resonators

A method for reduction of undesirable coupling between two antennas by means of a small resonant element is proposed. The parasitic resonant element is strongly excited by the aggressor antenna radiation and produces a cancellation effect at the victim antenna. This effect is achieved mainly due to the near field of the resonant circuit. Being electrically small the resonant element is an inefficient radiator, which only slightly affects the radiation patterns of the antennas. The proposed technique is demonstrated by reduction of coupling between two monopole antennas using a small capacitively loaded loop.