Power link budget for propagating Bessel beams

International audienceThe power link budget for a system that transmits and receives propagating Bessel beams is studied. The transmitter and receiver are separated by a distance D and consist of leaky radial waveguides. Full-wave simulations are used to compute the admittance-matrix representation of the system. The resonances of the coupled transmitter and receiver are then derived using classical network theory. For comparison purposes, a second configuration with its transmitter and receiver connected by a circular waveguide is considered. In contrast to the open system, such a configuration is closed and does not radiate. It is found that within the non-diffractive range of the Bessel beam, both closed and open systems exhibit the same resonances within an error of 0.6%. Calculations show that the power efficiency of the open system can exceed 85% within the non-diffractive range. The proposed system may find application in areas such as wireless power transfer, near-field communication and non-destructive evaluation

Generation of non-diffractive Bessel beams by inward cylindrical traveling wave aperture distributions

International audienceThe focusing capabilities of an inward cylindrical traveling wave aperture distribution and the non-diffractive behaviour of its radiated field are analyzed. The wave dynamics of the infinite aperture radiated field is clearly unveiled by means of closed form expressions, based on incomplete Hankel functions, and their ray interpretation. The non-diffractive behaviour is also confirmed for finite apertures up to a defined limited range. A radial waveguide made by metallic gratings over a ground plane and fed by a coaxial feed is used to validate numerically the analytical results. The proposed system and accurate analysis of non-diffractive Bessel beams launched by inward waves opens new opportunities for planar, low profile beam generators at microwaves, Terahertz and optics

Optimized analysis of slotted substrate integrated waveguides by a method-of-moments mode -matching hybrid approach

International audienceA full-wave hybrid formulation is proposed for the efficient and accurate modeling of substrate integrated waveguides by rigorously accounting for all possible interactions among elements such as vertical metallic or dielectric posts and coupling or radiating slots. The method is specifically accelerated in order to maximize the efficiency of the analysis of common structures. Its flexibility allows for the study of a large class of devices, possibly in stacked-waveguide configurations, and for the characterization of radiated fields and input port parameters

Efficient Computation of the Coupling Between a Vertical Line Source and a Slot

International audienceA novel spectral formulation is proposed here for the coupling integral between a cylindrical wave with arbitrary radial wavenumber and azimuthal dependence, and a slot placed on a plane orthogonal to the wavefront. Such a kind of integral is massively encountered in electromagnetic modeling of stratified structures comprising slots and vertical pins or vias. The twofold spatial integral defining the coupling is transformed into an equivalent onefold spectral integral, the integration path of which is selected to obtain Gaussian decay of the integrand. Both propagating and evanescent cylindrical modes are considered. An arbitrary stratification orthogonal to the slot plane can be considered, as well as an arbitrary current on the slot. Numerical comparisons against the standard spatial approach are shown to validate the new formulation, and its advantage in terms of computation cost is investigated in depth

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

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

Complex conical beams for aperture field representations

4siA method is presented for computing aperture radiated fields by means of new conical beams with azimuth phase variation. These beams are generated in a natural way starting from the spectral-domain radiation integral, by expanding the electric field spectrum in the aperture plane in a Fourier series, and by approximating the obtained Fourier series coefficients by a sum of complex exponentials using the generalized pencil-of-function method. This transforms the radiation integral to a simpler form which can be evaluated analytically. Two types of wave objects are derived, both of them arising from the same spectral GPOF process, that possess different properties. Aperture fields obtained via the new approach are successfully compared to those calculated via direct near field integration or asymptotic evaluation.reservedmixedSkokic, Sinisa; Casaletti, Massimiliano; Maci, Stefano; Sorensen, Stig BuskSkokic, Sinisa; Casaletti, Massimiliano; Maci, Stefano; Sorensen, Stig Bus