A Correlation Theory of Antenna Directivity With Applications to Superdirective Arrays

We develop a general approach to antenna directivity by combining the infinitesimal dipole model (IDM) and the cross-correlation Green's function (CGF) in a new formulation. The theory is deployed for the analysis and synthesis of antenna systems via the proposed IDM-CGF method after integration with global optimization algorithms. The IDM-CGF theory opens the door for hitherto unexplored connections between applications involving antenna gain engineering on one side, and multiple-input-multiple-output (MIMO) and diversity methods on the other, helping to devise new techniques for applications like massive MIMO and millimeter-wave beamforming algorithms, wireless power transfer, in-package antennas, and full three-dimensional isotropicity.