Leaky-Wave Metamaterial Antennas: Conical and Pencil Beam Radiation

In this paper, we review our recent work on conformal metamaterial antennas, based on the excitation of leaky modes in cylindrical shells with a sub-wavelength cross section. The physical principles of operation are recalled and the main features of metamaterial shells made by material with a negative (and close to zero) real part of the permittivity are reviewed. When the azimuthally-independent leaky mode, which is backward, is excited in this structure, a high- directive conical beam is radiated by the shell. This configuration can be used in regular omni-direcfional base station antennas. Some examples are presented in the paper. On the other hand, when higher-order leaky modes are excited, the shell is capable of radiating multiple directive beams. This shell can be used in point-to-(multi)point radio links, satellite communications, and in smart and switched beam antenna systems.