Decorrelating Closely Spaced Antennas by Pattern Design in Uniform Scattering Environments

Abstract

The authors propose a novel solution for decorrelating closely spaced antennas with identical radiation patterns. By proper steering of the directional elements’ patterns, the decorrelation distance is reduced to 0.25l in comparison with the well-established 0.4l result based on the Bessel-shaped correlation expression. In addition, by proposing the definition of Decorrelation Factor of an antenna pattern, a framework for comparison of correlation behaviour of different antennas is provided. Subsequently, a performance metric characterised by the Jensen upper bound for the capacity of closely spaced antennas is proposed. Finally, we apply our results to two practical directional antennas, namely, the half-wavelength dipole and the vertical electric dipole antennas and compare their correlation and capacity performance.