Bessel beam launchers at millimeter waves using higher-order leaky-wave modes

Near-field shaping is a topic of increasing interest due to a great number of diverse applications, such as medical imaging, diagnostics, power wireless transfer, near-field communications. In this context, focusing electromagnetic energy in certain regions of space is of paramount importance, and it can be achieved through the excitation of Bessel beams: their transverse dependence is of the kind of a nth order Bessel function Jn(·) and is invariant along the propagation direction within the so-called nondiffractive region.