Increasing the supergain of electrically small antennas using metamaterials

Uzkov´s determination of the maximum possible directivity (N²) of N isotropic acoustic radiators is generalized to antenna elements with the radiation patterns of crossed electric and magnetic dipoles (Huygens sources). In particular, it is shown that resonant Huygens-source elements forming an electrically small two-element parasitic (Yagi-like) array can, in principle, have a free-space gain as high as 9 dB. Two possible realizations of electrically small resonant Huygens sources are discussed: one modeled after an existing resonant miniature antenna, and a second consisting of resonant magnetodielectric spheroids.