Antenna Design Concepts Based on Transformation Electromagnetics Approach

Using the idea of wave manipulation via coordinate transformation, we demonstrate the design of novel antenna concepts. The manipulation is enabled by composite metamaterials that realize the space coordinate transformation. We present the design, realization and characterization of three types of antennas: a directive, a steered beam and a quasi-isotropic one. Numerical simulations together with experimental measurements are performed in order to validate the concept. Near-field cartography and far-field pattern measurements performed on a fabricated prototype agree qualitatively with Finite Element Method (FEM) simulations. It is shown that a particular radiation can be transformed at ease into a desired one by modifying the electromagnetic properties of the space around it. This idea can find various applications in novel antenna design techniques for aeronautical, telecommunication and transport domains

Study and analysis of an electric Z-shaped meta-atom

A printed Z-shaped electric meta-atom is presented as an alternative design to the conventional electric-LC (ELC) resonator. We propose to redesign the ELC resonator pattern to get a compact and a low cost electric resonator exhibiting a strong electric response. Our approach consists in redressing the resonator shape to accommodate higher inductance and therefore leading to a lower resonance frequency without being limited by fabrication tolerances. Simulation and measurement results show that the Z metaatom exhibits an electric response to normally incident radiation and can be used very effectively in producing materials with negative permittivity

A RECONFIGURABLE ELECTROMAGNETIC BANDGAP STRUCTURE FOR A BEAM STEERING BASE STATION ANTENNA

International audienceThe purpose of this communication is to present the works of a French Industry and Research sponsorized project (RNRT Project) named "BIP" [1]. The goal of this project was to design a beam steering multi-band (GSM/DCS/UMTS) base station antenna. After a presentation of the different partners, we will show how we would solved the problem of the beam steering antenna with a controllable Electromagnetic BandGap (EBG) structure and we will present the results of simulations and experiments in order to validate the concept

Novel antenna concepts via coordinate transformation

Coordinate transformation is an emerging field which offers a powerful and unprecedented ability to manipulate and control electromagnetic waves. Using this tool, we demonstrate the design of novel antenna concepts by tailoring their radiation properties. The wave manipulation is enabled through the use of engineered dispersive composite metamaterials that realize the space coordinate transformation. Three types of antennas are considered for design: a directive, a beam steerable and a quasi-isotropic one. Numerical simulations together with experimental measurements are performed in order to validate the coordinate transformation concept. Near-field cartography and far-field pattern measurements performed on a fabricated prototype agree qualitatively with Finite Element Method (FEM) simulations. It is shown that a particular radiation pattern can be tailored at ease into a desired one by modifying the electromagnetic properties of the space around radiator. This idea opens the way to novel antenna design techniques for various application domains such as the aeronautical and transport fields

Metamaterial-based Fabry-Perot leaky wave antennas: low profile, high directivity, frequency agility and beam steering

International Conference on Radio and Antenna Days of the Indian Ocean (RADIO), Flic en Flac, MAURITIUS, SEP 24-27, 2012International audienceThe analysis and design of subwavelength metamaterial-based Fabry-Perot (FP) leaky wave antennas (LWAs) are presented. The antennas under investigation are formed by embedding a feeding source in a cavity composed of a Perfect Electrical Conductor (PEC) surface and a metasurface reflector. Several configurations of such antennas are presented to achieve different desired performances such as: high directivity, frequency agility and beam steering

A picosecond Josephson junction model for circuit simulation

The first order series expansion of the time dependent Josephson equation allows a precise simulation of the switching dynamic of picosecond Josephson junctions. The junction model is quite as efficient as the RSJC model in computer calculations. Numerical examples illustrate its domain of application for picosecond junctions in a circuit environment by comparison with the RSJC model.La résolution au premier ordre de l'équation Josephson dépendant du temps permet d'etudier avec précision la dynamique de la commutation des jonctions Josephson de temps de commutation ≃ 1 ps. La modélisation obtenue pour la jonction est presque aussi facile d'emploi que le modèle RSJC dans les calculs numériques. Des exemples illustrent le domaine d'application de la méthode par rapport au modèle RSJC en fonction de 1'environnement de la jonction

Properties of Metallic Photonic Band Gap material with defect at microwave frequencies: calculation and experimental verification

In this paper, the properties of a Metallic Photonic Band Gap Prism (MPBGP) with defects are studied. The MPBGP is made of metallic rods disposed in an isosceles right-angled triangle. The commercial software HFSS based on the finite element method is used to study the behavior of Photonic Band Gap structure by means of three-dimensional dispersion diagrams, iso-frequency curves, radiation patterns and the cartography of electric field. Numerical results showed that the metallic photonic band gap without and with defects behaves like a homogeneous and ultrarefractive medium in the first allowed frequency band. The distribution of defects doesn't modify the propagation of electromagnetic waves through the metallic photonic band gap material, it has properties similar to that of a perfect prism. In the forbidden frequency bands, the anomalous transmission has been obtained by means of surface defects in Metallic structure. This anomalous transmission in forbidden band has also been observed in simulations carried out on a dielectric photonic band gap material made of dielectric rods disposed in an isosceles right-angled triangle. Theoretical results presented in this paper have been successfully validated by measurements carried out in the frequency range [7-16 GHz]

Analytical expressions of the turn on delay and the rise time of very fast Josephson junctions

We develop approximate analytical expressions of the turn on delay and the rise time for very fast Josephson junctions (1-5 ps). Such expressions are useful in the first steps of circuit design with speed optimisation. The principal configurations met in direct coupled Josephson logic circuits are treated and the results are compared with the corresponding quantities of the RSJC model

Analytical expressions of the turn on delay and the rise time of very fast Josephson junctions

We develop approximate analytical expressions of the turn on delay and the rise time for very fast Josephson junctions (1-5 ps). Such expressions are useful in the first steps of circuit design with speed optimisation. The principal configurations met in direct coupled Josephson logic circuits are treated and the results are compared with the corresponding quantities of the RSJC model.Nous développons des expressions analytiques approchées du temps de retard au déclenchement et du temps de montée des jonctions Josephson rapides (1-5 ps). Les principales configurations rencontrées en logique Josephson à couplage direct sont traitées et les résultats obtenus sont comparés avec ceux issus du modèle RSJC. De telles expressions sont utiles dans les étapes initiales de la conception de circuits logiques optimisés en vitesse