Low profile lens antennas: Collimating leaky-wave radiation with metasurfaces

Two lens-antennas with a subwavelength overall thickness are reported. The lens-antennas consist of a meta surface lens placed a subwavelength distance above a planar, leaky radial waveguide that generates a TM-polarized Bessel beam (Bessel beam launcher). Two different meta surface lenses are designed to collimate the radiation from the Bessel beam launcher and convert the polarization from radial to linear and circular, respectively. The two lens-antennas are fabricated using standard printed circuit board processes, and their performance is experimentally characterized. The same design procedure could be used to realize metasurfaces that control the radiation of an arbitrary source.