Efficient design of rectifying antennas for low power detection

ISSN : 0149-645X E-ISBN : 978-1-61284-756-6 Print ISBN: 978-1-61284-754-2 INSPEC Accession Number: 12240657International audienceThis article is dedicated to the design of rectifying antenna for wireless energy transfer at 2.45 GHz and low input power (−10 dBm). Specific design guidelines must be respected to optimize the structure. Different rectifying circuits have been studied and their performances have been evaluated. The effects of the antenna impedance have been investigated to improve the performances. Two test-circuits have been manufactured and measured to validate the interest of a global design approach

Prognosis of cirrhotic patients admitted to intensive care unit: a meta-analysis

and METAREACIR GroupInternational audienceBackgroundThe best predictors of short- and medium-term mortality of cirrhotic patients receiving intensive care support are unknown.MethodsWe conducted meta-analyses from 13 studies (2523 cirrhotics) after selection of original articles and response to a standardized questionnaire by the corresponding authors. End-points were in-ICU, in-hospital, and 6-month mortality in ICU survivors. A total of 301 pooled analyses, including 95 analyses restricted to 6-month mortality among ICU survivors, were conducted considering 249 variables (including reason for admission, organ replacement therapy, and composite prognostic scores).ResultsIn-ICU, in-hospital, and 6-month mortality was 42.7, 54.1, and 75.1%, respectively. Forty-eight patients (3.8%) underwent liver transplantation during follow-up. In-ICU mortality was lower in patients admitted for variceal bleeding (OR 0.46; 95% CI 0.36–0.59; p 19 at baseline (OR 8.54; 95% CI 2.09–34.91; p 26 (OR 3.97; 95% CI 1.92–8.22; p < 0.0001; PPV = 0.75), and hepatorenal syndrome (OR 4.67; 95% CI 1.24–17.64; p = 0.022; PPV = 0.88).ConclusionsPrognosis of cirrhotic patients admitted to ICU is poor since only a minority undergo liver transplant. The prognostic performance of general ICU scores decreases over time, unlike the Child–Pugh and MELD scores, even recorded in the context of organ failure. Infection-related parameters had a short-term impact, whereas liver and renal failure had a sustained impact on mortality

Spitzer Follow-up of Extremely Cold Brown Dwarfs Discovered by the Backyard Worlds: Planet 9 Citizen Science Project

We present Spitzer follow-up imaging of 95 candidate extremely cold brown dwarfs discovered by the Backyard Worlds: Planet 9 citizen science project, which uses visually perceived motion in multi-epoch WISE images to identify previously unrecognized substellar neighbors to the Sun. We measure Spitzer [3.6]-[4.5] color to phototype our brown dwarf candidates, with an emphasis on pinpointing the coldest and closest Y dwarfs within our sample. The combination of WISE and Spitzer astrometry provides quantitative confirmation of the transverse motion of 75 of our discoveries. Nine of our motion-confirmed objects have best-fit linear motions larger than 1"/yr; our fastest-moving discovery is WISEA J155349.96+693355.2 (total motion ~2.15"/yr), a possible T type subdwarf. We also report a newly discovered wide-separation (~400 AU) T8 comoving companion to the white dwarf LSPM J0055+5948 (the fourth such system to be found), plus a candidate late T companion to the white dwarf LSR J0002+6357 at 5.5' projected separation (~8,700 AU if associated). Among our motion-confirmed targets, five have Spitzer colors most consistent with spectral type Y. Four of these five have exceptionally red Spitzer colors suggesting types of Y1 or later, adding considerably to the small sample of known objects in this especially valuable low-temperature regime. Our Y dwarf candidates begin bridging the gap between the bulk of the Y dwarf population and the coldest known brown dwarf.Comment: accepted for publication in The Astrophysical Journa

Antenna provided with an assembly of filtering materials

Priority number: FR19990014521 19991118 FR2801428 (A1) 25/05/2001 Egalement publié comme: ANTENNA PROVIDED WITH AN ASSEMBLY OF FILTERING MATERIALS CA2360432 (A1) 25/05/2001 CA2448636 (A1) 25/05/2001 AU1868401 (A) 30/05/2001 EP1145379 (A1) 17/10/2001 EP1416586 (A1) 06/05/2004 CN1337078 (A) 20/02/2002 CN1519988 (A) 11/08/2004 JP2003514476 (T) 15/04/2003 AT336091 (T) 15/09/2006 AT371964 (T) 15/09/2007 DE60030013 (T2) 22/02/2007 DE60036195 (T2) 15/05/2008 ES2269897 (T3) 01/04/2007 ES2292491 (T3) 16/03/2008An antenna includes a probe capable of transforming electrical energy into electromagnetic energy and inversely. It further includes an assembly of elements made of at least two materials different in permittivity and/or permeability and/or conductivity within which the probe is arranged, the arrangement of the elements in the assembly ensuring radiation and spatial and frequency filtering of the electromagnetic waves produced or received by the probe, which filtering allows in particular one or several operating frequencies (f) of the antenna inside a frequency band gap (B)

Méthodes d analyse électromagnétique spécifiques à la conception des antennes à résonateur BIE multi sources

La mise en réseau de sources d excitation au sein d un résonateur BIE permet de bénéficier à la fois des avantages des réseaux (tels que la formation de faisceau, création de zéros de rayonnement, faisceaux dépointés) et du caractère filtrant du résonateur (filtrage spatial, augmentation de directivité, dépointage). Ce manuscrit présente un ensemble de démarches adaptées à la conception et au développement des antennes BIE et en particulier des antennes BIE multi sources. Le calcul de la fonction Sélectivité spatiale est d abord présenté. Cette fonction traduit le caractère filtrant du résonateur BIE. Pondérée par le diagramme de rayonnement d une source, cette fonction permet d analyser rapidement ses performances. La seconde partie du travail est consacrée à la problématique de l excitation multi sources. Cette partie est illustrée avec la conception, la réalisation et la mesure de deux prototypes. De part le caractère résonant de ce type de structure, la démarche de conception est plus délicate. En effet, l antenne BIE exacerbe les phénomènes de couplage inter éléments déjà présents dans les antennes multi sources. Pour cette raison, une nouvelle méthode permettant de lever cette difficulté a été développée.A feeding sources arrangement installed in an EBG resonator leads to profit at the same time from the array advantages (such as beamforming, nulling patterns, beam steering) and the resonator filtering attributes (spatial filtering, directivity increasing, steering). This report presents a set of steps that is adjusted to the EBG antennas development and design in particular multi sources EBG antennas. First, a spatial function computation is presented. This function results in the EBG resonator filtering attributes. Weighting the EBG resonator by a source radiation pattern allows the defined function to quickly evaluate the EBG performances. The second part focuses on the multi sources feeding problems. The goal of this part is to design and realize two prototypes. Then, the measures come to validate the antenna design. Aside from the resonating attributes of this kind of structure, the design steps are more tricky. Indeed, the EBG antenna intensifies the coupling phenomena between the radiating elements in the multi sources antennas. For this reason, a novel method overcoming the coupling complication was developed.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Développement du concept de l'antenne à résonateur BIE pour la génération de la polarisation circulaire

Ce mémoire est consacré au développement du concept de l antenne à résonateur BIE pour la génération de la polarisation circulaire. Deux types d antenne ont pu être réalisées à l aide des propriétés isotropes et anisotropes des matériaux BIE. L excitation d une matériau BIE isotrope par un patch à encoches a abouti à la réalisation d une antenne BIE à polarisation circulaire permettant ainsi d élaborer deux systèmes en polarisation circulaire : l antenne multifréquences et l antenne à diversité de polarisation. Un agencement anisotrope combinant un matériau BIE métallique et un polariseur a rendu la structure autopolarisante permettant ainsi de créer une antenne BIE à polarisation circulaire à l aide d une source en polarisation linéaire. Les réalisations présentées dans ce mémoire confirment avec succès les différentes structures proposées.This report is dedicated to the development of the resonator EBG antenna concept for generating circular polarization. Two different structures have been realized by using the isotropic and anisotropic properties of EBG materials. The excitation of an EBG isotropic material by a patch antenna with notches ended with the conception of an antenna with circular polarization thus allowing to elaborate two systems in circular polarization: the multifrequency antenna and the antenna for diversity of polarization. An EBG anisotropic structure, combining a metallic EBG material and a polarizer, created a polarizing structure allowing to create an EBG antenna radiating in circular polarization with a source in linear polarization. The presented realizations successfully confirm the various proposed functioning.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Frequency multiband antenna with photonic bandgap material

Première publication : Multifrequency multiband antenna having photonic band gap material with single periodicity defect band gap producing several narrow bandwidths and excitation mechanism producing electromagnetic transmitter receiver - Priority number: FR20030009467 20030731 - FR2854738 (A1) 12/11/2004 - Egalement publié comme: FREQUENCY MULTIBAND ANTENNA WITH PHOTONIC BANDGAP MATERIAL EP1554776 (A1) 20/07/2005 US2006097917 (A1) 11/05/2006 WO2004040695 (A1) 13/05/2004 AU2003285445 (A1) 25/05/200

Synthèse de propriétés d'agilité électromagnétique par des matériaux artificiels périodiques intégrant des microcomposants (application à la conception d'antennes à résonateur BIE configurables)

Dans le domaine des antennes, les structures composées d un agencement périodique d éléments, de type à Bande Interdite Electromagnétique (BIE) ou les Surfaces Sélectives en Fréquence (FSS), sont très utilisées. Ces structures disposent de propriétés électromagnétiques dispersives et anisotropes originales, qui permettent de réaliser des fonctions de filtrage spatial et fréquentiel. L antenne BIE est réalisée à partir de ces matériaux. Dans ce mémoire, une étude de l intégration de microcomposants au sein de matériaux à structure périodique est réalisée. Ces microcomposants permettent ainsi de réaliser des matériaux aux propriétés électromagnétiques configurables, applicables à la conception d antennes agiles. Des réalisations d antennes BIE commutables en fréquence sont présentées dans cette thèse.In antenna domain, structures composed of periodic cells, like Electromagnetic Band Gap (EBG) or Frequency Selective Surfaces (FSS), are used. Strange Electromagnetic properties of these structures allow to realize spatial and frequency filter. EBG antennas use this kind of materials. In this report, a study of the integration of microcomponents in periodic structure is realized. These components allow to design material with configurable electromagnetic properties. In this thesis, realization of a frequency tunable EBG antenna is presented.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF