Generation of non-diffractive bessel beams using leaky-wave modes

This paper presents a novel direction in leaky-wave phenomenon research: the generation of non-diffractive Bessel beams by leaky-wave modes. A radial waveguide loaded by a capacitive impedance sheet is used to support an azimuthally invariant leaky-wave mode whose normal electric-field component is a truncated, zeroth-order Bessel function. In particular, the generation of propagating Bessel beams using the lowest and higher-order leaky-wave modes supported by the radial waveguide is considered. Design relations are provided in both cases, based on an accurate vector field approach and on the dispersion analysis of the proposed structure. Measurement results validate the design approach for the lowest order leaky-wave radial waveguide. Numerical results are presented for the higher-order case. Non-diffractive Bessel-beams may find application in sensing and wireless power transfer at microwaves and millimeter waves.