Design and Experimental Validation of an E-Band Wideband Bessel-Beam Launcher on Quartz

Radially periodic Bessel-beam launchers are typically fed with coaxial probes, as they provide a simple and effective means to obtain TM-polarized Bessel beams. However, as the frequency increases, coaxial feeders become increasingly expensive and fragile. Therefore, the realization of Bessel-beam launchers at (sub)millimeter-wave frequencies calls for alternative technologies. To illustrate this challenge and propose an effective solution, an E-band (81–86 GHz), radially periodic, leaky-wave Bessel-beam launcher is designed and experimentally validated in this work. The device is realized using a grounded dielectric slab with an annular metal strip grating on top and is fed through a waveguide mode converter. Specifically, the input fundamental mode of a standard rectangular waveguide is converted into the higher-order TM $_{01}$ mode of a circular waveguide, which feeds the launcher, thereby generating a TM-polarized Bessel beam. Full-wave and measurement results show impressive agreement with those theoretically predicted by an established leaky-wave approach.