A leaky radial waveguide for generating propagating Bessel beams

We report a leaky radial waveguide that can generate propagating Bessel beams by supporting an azimuthally invariant leaky-wave mode. The normal electric-field component of the mode is a truncated, zeroth-order Bessel function. Design relations for the radial waveguide are provided based on a vector field approach in contrast to previous scalar-based approaches. Electric field measurements and their respective Fourier transforms validate the operation of the prototype as a Bessel-beam launcher. In particular, the Fourier transform of the measured electric field exhibits a ring in the spectral domain at the operating frequency, as expected for Bessel beams. The proposed structure can be used for generating arbitrary zeroth-order propagating Bessel beams at microwave or millimeter-wave frequencies.