This paper presents a novel Y shaped fractal defected ground structure (FDGS) for the mutual coupling (MC) reduction between coplanar closely spaced microstrip antennas. The proposed FDGS has band-gap characteristic, which induces the current distribution on the antenna patch. This will contribute to achieving 25 dB MC reduction. When realizing the MC reduction, the antenna efficiency is increased. Moreover, the envelope correlation of the MIMO system is decreased, which helps to increase the MIMO system capacity.
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