Sebastien Clauzier

Design of Near-Field Synthesis Arrays Through Global Optimization

We provide a study of the relation between the near- and far-fields in antenna systems by working with a concrete design problem. The task of finding an antenna array capable of synthesizing a desired near-field distribution is tackled within the general framework of near-field theories recently proposed in literature. We use a genetic algorithm to search for a set of small antennas by working only with far-field data. It is shown, as predicted theoretically, that such information in the far zone are sufficient for reconstructing the entire near-field in the exterior region. We provide a set of examples demonstrating the procedure and validating the proposals. The methodology can be applied to arbitrary antennas and any desired near-field pattern, and we hope it will help automating design methods in the emerging research area of near-field array synthesis.

A 2.45 GHz novel electrically small planar dipole antenna

In this paper a novel electrically small planar dipole antenna operating at 2.45 GHz is proposed. This antenna exhibits small dimensions of 11.2×5.1×1.575 mm3 (0.09×0.04×0.01 λ03) which is considered to be one of the smallest ever reported footprints at this operating frequency. It has a simulated realized gain of 1.17 dBi along with an estimated efficiency of 87.4%. Due to the fact that ESAs are not self-resonant by nature, an impedance matching network has to be utilized to tune the antenna to resonate at the desired operating frequency. Three different matching approaches are studied in this paper. Finally, the antenna is modelled using the infinitesimal dipole model.

Design of high-diversity gain MIMO antenna arrays through surface current optimization

In this paper, we present a general method for obtaining MIMO antenna current distribution with optimum cross-correlation diversity gain. The method is illustrated with an example of 3-element arrays of wire antenna operating at 60GHz.

Generalized methodology for antenna design through optimal infinitesimal dipole model

Through two different applications (a MIMO system and a superdirective antenna array), we will show in this paper that a complete surface current optimization on an antenna allows the design of an optimal antenna system. For example, this surface current optimization can be applied to a MIMO system through a minimization of the cross-correlation coefficient or a superdirective antenna array with a maximization of the overall directivity.

A slotted waveguide based MIMO antenna system for wireless access points

In this work, a slotted rectangular waveguide (SRWG) with multiple input multiple output (MIMO) antenna configuration for wireless access points is presented. The MIMO antenna system consists of 4 elements and operates from 5 to 6 GHz. A Genetic Algorithm (GA) was applied to find the optimized position of the slots. A gain of 13.2 dB was obtained over the whole band. The dimensions of the waveguide (WG) were considered according to a standard WG WR159. The Size of a single element WG was 40.38 × 20.1 × 308.06 mm3. The beam of the antenna was tilted by 15°, while the side lobe level (SLL) on average over the whole band was 14.25 dB. The envelope correlation coefficient (ECC) of the MIMO design was 0.002 which represents highly uncorrelated beams.

High power pattern reconfigurable phased antenna array based on a GaN HEMT

A phased array antenna designed to achieve half power beam-width (HPBW) reconfiguration for high power microwaves (HPM) applications is presented. The radiation pattern is actuated according to a current phase distribution calculated using an infinitesimal dipole model (IDM) algorithm. A low profile antenna has been designed to be compatible with a small dipole model. This article particularly details the power amplifier which is designed to generate the high power signals. It is based on a GaN high electron mobility transistor (HEMT) to theoretically deliver up to 50W of power. The developed layout as well as the simulated and the measured performances are finally presented.

A new approach for near-field synthesis

We present an overview of a method for designing near-field focusing systems, where distributions of electrically-small antennas are used as the source. The technique proposed here relies on recent progress in the theoretical understanding of the relation between the far and near fields of generic antennas, where it is suggested that the entire exterior-domain near field can be reconstructed from far-field data. The present paper provides a brief description of the method and proof of concept via an example.

A method to obtain current distributions on small antennas with optimum directivity

The purpose of the present paper is to introduce new method for designing electrically-small antennas with optimum directivity. A sphere with small radius compared to the wavelength contains a distribution of infinitesimal point sources. Global optimization is used to find the best current on the small antenna enclosed within this sphere capable of providing the optimum directivity. The results presented in this paper are compared with the antenna directivity limit for small antennas found in the literature.