Bessel‐Beam Antennas

Abstract

The capability of controlling the spatial broadening of the radiation moving away from the relevant sources is considered a very attractive feature for a plethora of applications, such as imaging, diagnostic, and wireless power transfer. An important class of ideal solutions of the scalar wave equation that remain confined and do not undergo diffracting spreading are the so‐called Bessel beams.In the past few decades, several techniques have been proposed to design zeroth‐ and higher order Bessel beams, all based on the scalar wave theory.More recently, a significant amount of research activity has been devoted to design devices and techniques for the generation of Bessel beams at lower frequencies, thus based on conventional vector solutions of Maxwell's equation. A comprehensive review of the most representative approaches constitutes the main goal of this article.

Analysis of Bessel Beam Generation Using MetaMaterials in Photonic Integrated Circuits

“…The equation below shows the relationship between Z, the non-diffracting range, the transverse wavenumber 𝑘 𝜌 , and the radius R, of the emitting plane of the aperture. [2,[16][17][18]:…”

Leaky-Wave Analysis of TM-, TE-, and Hybrid-Polarized Aperture-Fed Bessel-Beam Launchers for Wireless-Power-Transfer Links

“…By enforcing a TM or TE radial resonance with a Bessel-like field distribution, due to the limited-diffraction behavior of BBs, we can assume an invariant aperture field at each z-plane for 0 ≤ z ≤ z ndr , being z = 0 the aperture plane and z ndr the so-called nondiffractive range [12]. We recall here that for truncated BBs, the nondiffractive range takes the following approximate expression: z ndr = ρ ap cot θ 0 (10) where θ 0 is the so-called axicon angle (evaluated with respect to the vertical z-axis) that can be found through the relation β = k 0 sin θ 0 , regardless of the polarization type of the launcher. In addition, when BBs are generated through leaky waves [39], and the effective nondiffractive range is reduced in amounts that depend on the leakage rate (see [40, eq.…”

“…In Sections II and III, we have shown how the aperture-field distribution of a BB launcher, excited by an HMD aligned along the x-axis, can theoretically be found. In a zerothorder approximation of ideal, diffraction-free propagation, such an aperture field can be used to represent the near field within the nondiffracting range given by (10). More accurate results with respect to this aperture-field approximation can be obtained by using the Huygens-Fresnel radiation integral.…”

“…In this regard, localized beams at microwave and millimeter-wave frequencies [5], [6], [7], and in particular Bessel beams (BBs) [8], [9], have attracted much interest due to their focusing, self-healing, and limited-diffractive properties. Devices capable of radiating such beams are also known as launchers and are commonly distinguished between resonant and wideband launchers (see, e.g., [10], [11], and references therein). The former have the advantage of being compact in size, but typically show a narrow fractional bandwidth (FBW) due to their resonant nature [12], [13], [14], whereas the latter present a wideband behavior at the expense of an electrically large aperture size [15], [16], [17], [18], [19] and/or nonplanar, lens-like designs [20], [21], [22], [23], [24].…”

Circular Airy-like beams through leaky-wave antennas

“…Airy beams (ABs) have attracted considerable interest thanks to a number of interesting properties [1][2][3][4][5][6]: they can be weakly diffractive compared to, e.g. Gaussian-like beams, exhibit a self-healing character (as per Bessel beams [7,8]), and have the ability to abruptly focus their energy towards a point in front of a planar aperture [9][10][11]. ABs have initially been defined for two-dimensional (2D) propagation [1].…”