Reduction of mutual coupling between closely-packed antenna elements using defected ground structure

A simple ground plane structure that can reduce mutual coupling between closely-packed antenna elements is proposed. The structure consists of a dumb-bell-like pattern etched in a single ground plane. It is found that isolation of more than -40 dB can be achieved between two parallel individual planar inverted F antennas (PIFAs) sharing a common ground plane. Comparison of the proposed dumb-bell-like defected ground structure (DGS) with other approaches shows its unique capability of reducing mutual coupling. Influence of the designed DGS on radiation pattern and surface current distribution on the ground plane is also investigated.