Spiral antennas for the generation of bessel beams with tunable nondiffractive range

Abstract

Backward cylindrical leaky waves radiating in the direction of their central axis represent an efficient solution for generating nondiffracting Bessel-like beams. The structures proposed so far to support such waves, constituted by concentric metal rings printed on a grounded dielectric slab, ensure the formation of nondiffractive field patterns with preset unchangeable configurations at a given frequency. Here, we propose the adoption of subwavelength spiral filaments with controlled patterning of the envelope figure by dynamic mechanical deformations, in order to achieve spatial tuning of the nondiffractive region in its size and shape. Precise guidelines and examples are provided to describe the proposed design technique and underline the inherent advantages of this alternative technological solution.

Vortex circular airy beams through leaky-wave antennas

“…The first one is based on a BE-LWA, already considered in [37] with a single centered coaxial probe for the synthesis of azimuthally invariant CABs with zero OAM, now fed by a circular phased array of sources (see figure 1, up-left scheme). The second one is based on a multispiral (MS) LWA fed by a single coaxial source (see figure 1 top-right scheme), already considered in [38] for the emission of Bessel beams with tunable nondiffracting range.…”