Generation of Bessel Beams by Two-Dimensional Antenna Arrays Using Sub-Sampled Distributions

Abstract

Bessel beams are proposed as a practical way to generate well collimated and confined beams at mm-waves or THz for quasi-optical applications. To achieve that, we propose the use of two-dimensional antenna arrays as realizable launchers. Truncated Bessel beams with a main lobe width of few wavelengths $(\lambda)$ can propagate over several hundreds of $\lambda$ if the antenna aperture is electrically large. Because such a large aperture would require a large number of antenna elements, sub-sampling distributions are proposed in this work. It is found that arrays with spacings of approximately $4\lambda$ generate high quality beams with very low amplitude oscillations over distances of about $300\lambda$ in vacuum. The optimal excitation function for such arrays greatly departs from the Bessel one. It is synthesized with an analytical method based on a least mean square error minimization. The synthesis method is scalar, but the pseudo-Bessel beams obtained are vectorial and linearly polarized. Theoretical predictions are confirmed by full-wave simulations using Ansoft Designer.