A Loaded Decoupling Surface Method for MIMO Antenna Arrays

A decoupling method using loaded decoupling surface (LDS) for multiple-input–multiple-output (MIMO) antenna arrays is presented. To mitigate the direct electromagnetic coupling between array elements, an LDS is employed to generate a neutralizing wave that counteracts the original antenna coupling. A network model is developed to establish the relationship between antenna coupling and the LDS, enabling an accurate determination of the load impedance at the LDS for optimal isolation. To validate the proposed decoupling methodology, a 2 × 2 planar array with LDS centered at 4.85 GHz is proposed, and corresponding theoretical study is conducted as well. The simulated and measured results demonstrate that coupling levels are all effectively reduced to lower than −32.0 dB for both adjacent and nonadjacent units within the operation band, making the proposed LDS method suitable for MIMO applications.