Planar antenna design for omnidirectional conical radiation through cylindrical leaky waves
An annular periodic leaky-wave antenna (LWA) fed by a simple azimuth-symmetric source is designed to generate a high-gain omnidirectional conical beam pattern which scans with frequency over a wide angular range. The proposed structure is defined by a finite metallic radial strip grating printed on a grounded dielectric slab which supports an n = 0 cylindrical leaky wave (CLW) mode. The distinctive features of CLWs supported by such a truncated structure are also highlighted and discussed. The directional far-field pattern generated by the proposed LWA, in conjunction with its non-diffracting and wideband behavior in the near-field (as previously reported by the authors), defines an original dual-operational LWA. Possible applications include next-generation wireless power transfer systems that provide functionality in both the near and far field, vehicle roof-mounted antennas for base-station data connectivity as well as future short-range near-field communications, and object tracking by device ceiling-mounting for indoor localization.