On the Near-Field Shaping and Focusing Capability of a Radial Line Slot Array

Abstract

International audienceWe describe the design of a radial line slot array antenna with a shaped and focused near field. The antenna is designed in such a way to control the side lobe level and beamwidth of the normal component of the electric field with respect to the radiating aperture. The design procedure consists of two steps. In the first step, the requirements on the near-field pattern are provided over a focusing plane at a given distance from the radiating aperture. A set theoretic approach is then used to derive the aperture field distribution fitting the requirements over the near field. In the second step, the aperture field distribution is synthesized by accurately placing and sizing the slots of the antenna. The spillover efficiency is maximized during the design process. The antenna is centrally fed by a simple coaxial probe. The antenna design is validated by a prototype and measurements at 12.5 GHz

Experimental Validation of Bessel Beam Generation Using an Inward Hankel Aperture Distribution

“…The required azimuthally invariant inward Hankel field aperture distribution is synthesized by an RLSA antenna at the operating frequency of f = 12.5 GHz using the optimization procedure outlined in [10]. This procedure controls the position and size of each slot of the RLSA antenna in such a way to create, over the radiating aperture, the equivalent magnetic current distribution associated with the inward Hankel wave:…”

“…In addition, the antenna spillover efficiency (ratio between the radiated and accepted power by the antenna) is maximized during the design to prevent spurious radiation from the edge of the structure. In the following, an efficiency larger than 95% has been imposed as constraint [10]. The slots of the RLSA and the associated magnetic dipole moments are oriented along φ as the equivalent magnetic current distribution.…”

“…The width of the slots (w) is equal to 1.2 mm. A spillover efficiency larger than 97% and an average aperture distribution error lower than 4.5% are achieved at the end of the optimization loop [10]. The antenna is fed by a coaxial probe transition as shown in the inset in Fig.…”

“…This beam is generated by imposing an inward azimuthally invariant traveling wave distribution H Here, the finite aperture is synthesized by a radial line slot array (RLSA) antenna. The optimization procedure outlined in [10] has been used for defining the size and position of the slots of the RLSA antenna. It is worth mentioning that a similar procedure has been adopted in [11] for the generation of a circular polarized Bessel beam by an RLSA structure [12].…”

Control of phase in radial line slot antenna for 5G communications at 60GHz

“…As long as these antennas can be seen as continuous apertures that have been sampled, a first study using continuous sources will be done. M. Ettorre et al presented in [5] a method for designing RLSA antennas for near field focusing.…”