However, the truth is that an ideal Bessel beam does not exist due to the fact that they are not square integrable. This is the basis idea for launching Bessel beams. An ideal Bessel beam can be thought to be a superposition of plane waves with wave vectors lying on a cone. Bessel beams are of considerable potential applications such as electromagnetic propulsion, remote power transmission and secure communication. The beam exhibits the property of remaining confined and not suffering diffractive propagating. The non-diffracting beam solutions to the free-space homogeneous MaxwellвЂ™s equations, i.e., the Bessel beams, were proposed by Durnin in 1987 1. Full-wave simulation and experiment results have proved that the generated Bessel beams can be maintained in distance larger than 1вЂ‰meter within a ranging from 12вЂ‰GHz to 18вЂ‰GHz. To verify the approach, we have designed, fabricated and tested a metamaterial lens.

In principle, this kind of metamaterial lens can produce Bessel beams at arbitrary distance by designing the refractive-index distribution. The aperture diameter of the GRIN lens is much larger than the operating wavelength to guarantee the transformation. The conical beams form quasi-Bessel beams in the near-field region.

The metamaterial lens serves as a convertor which transforms the spherical beams emitted from feed into conical beams. The metamaterials are designed as dielectric plates printed with metallic patterns in the center region and drilled by air holes near the edge, which operate in wide band. The metamaterial lens is constructed with multi-layered structure and each layer is composed of GRIN metamaterials. The broadband Bessel beams are produced by a gradient index (GRIN) metamaterial lens illuminated by broadband waveguide antenna. An approach of generating broadband Bessel beams is presented.

Bessel beam in cst microwave studio