RLSA Bessel beam launchers using Hankel waves

In this paper the focusing capabilities of a radiating aperture taking on an Hankel-like distribution are demonstrated. In the case of an infinite aperture distribution, an analytical approach is followed. In the case of an inward Hankel wave, the ideal non-diffractive Bessel beam shape is observed for the longitudinal z-component of the electric field in a conical region close to the axis of symmetry of the aperture. In the finite case, an asymptotic approximation is used to evaluate the diffractive contributions due to the aperture truncation and to verify the conclusions of the infinite case. A radial waveguide loaded with annular slots is therefore designed and optimized as a practical implementation of the proposed Bessel beam launcher validating the theoretical results.