Ricerc@Sapienza

In this contribution, we describe the design and the radiation features of a dual-mode operation low-profile, low-cost, wideband antenna. The structure is made by an annular, 2-D radially periodic, leaky-wave antenna enabling the generation of both high-gain beams in the far-field and of nondiffracting waves within the near-field radiative region. This is obtained through the generation of a fast backward spatial harmonic supported by a metal-strip grating placed on a grounded dielectric slab. The radiation can be then described by means of a cylindrical leaky-wave dominating the aperture field of the antenna, whose dispersive behavior is properly taken into account. The high-gain radiation features and the focusing capabilities of the device are experimentally investigated and described. Thanks to the dual-mode capability, the proposed design represents an attractive, simple, and innovative solution for next-generation wireless power transfer devices, for tracking or automotive anticollision systems as well as for advanced microwave imaging.