This paper deals with the influence of artificial magnetic conductors (AMC), so called Sievenpiper high impedance surfaces (HIS), on the MIMO and diversity performance of a planar linear-polarized 2 times 2 dipole array at 2.45 GHz. By means of full-wave electromagnetic analysis (ANSOFTF HFSS) as well as a statistical channel model implementation the characteristic performance criteria such as envelope correlation, spectral efficiency, mean effective gain (MEG) and diversity gain of a coupled 2 times 2 dipole array are investigated. The obtained results justify the use of HIS for designing efficient low profile antenna setups in future communication systems due to the achieved MIMO and diversity performance compared to ideal configurations in free-space.