Yes / A printed dipole antenna integrated with a duplex RF switch used for mobile base station antenna beam steering is presented. A coplanar waveguide to coplanar strip transition was adopted to feed the printed dipole. A novel RF switch circuit, used to control the RF signal fed to the dipole antenna and placed directly before the dipole, was proposed. Simulated and measured data for the CWP-to-CPS balun as well as the measured performance of the RF switch are shown. It has demonstrated the switch capability to control the beam in the design of beam steering antenna array for mobile base station applications.

Networks which use real-time communication have high requirements on latency and packet loss. Improving one aspect may results in worse performance for another, and it can be difficult to prioritize one over the other as all the requirements need to be met in order for the network tooperate as expected. Many studies have investigated reducing the size of packet buffers to improve the latency. However, they have mainly focused on studying TCP traffic which may not be optimal for real-time traffic, where it instead could be more suitable to use UDP. We have performed an experiment where we compared the performance of real-time traffic over multiple different buffer sizes. We generated traffic using synchronized bursts of packets which were either sample value (SV) or IP packets, as defined by IEC 61850. We measured the packet loss and latency for situations where the traffic was either entirely composed of SV packets, or when it had mixed SV and IP traffic. For the mixed traffic, we also experimented with using different VLAN priorities for the two types of packets. We have determined deadline thresholds that show what size of packet buffer will start causing packets to miss their deadline, and what size will lead every packet in bursts oftraffic to miss their deadlines. We also found that increasing the priority of SV packets in mixed traffic can have either a positive or a negative impact on their performance, depending on how highly they are prioritized.

Photoconductive microwave switches can be used in place of traditional microwave switches to reconfigure antennas and RF circuits. The switch, which consists of a silicon die placed over a gap in transmission line, is controlled by illumination via a fibre optic cable. Hence there is no requirement to design electrical biasing lines which may affect RF performance. This benefit is the main motivation behind further developing and understanding the photoconductive switch. The second motivation is the growing demand for reconfigurable antennas which necessitate certain switching requirements; one specific area of interest is in cognitive radio applications. However, in order to use such a switch in RF circuitry, the photoconductive nature of the switch must be understood. This is addressed in this thesis presenting and applying analytical equations which dictate the material properties in photoconductive silicon. These equations are then used to generate a 3D EM simulation model to investigate transmission loss in the photoconductive switch. The concept of signal planarity is investigated so as to give some insight into the best way to package the switch. In order to potentially reduce loss and facilitate a packaged device, the fabrication of the switch is investigated. Namely, the treatment of the silicon and the addition of contacts on the silicon are discussed as possible methods to improve switch performance. Lastly, linearity, power handing and switching times are presented for the photoconductive switch. This characterisation is important with regards to understanding which types of application the switch can be used in. In particular the single tone and two tone linearity of the switch is measured these values have not previously been reported for this type of photoconductive switch. The results are encouraging and support further development of the switch into a packaged product to be used in reconfigurable antennas and circuitry.

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No description available.

With financial liberalization and economic globalization, international trade and capital transactions result in larger exchange rate fluctuations than in the past. Besides, it can¡¦t be ignored that the change of exchange rate influences the economics and real exchange rate which be regarded as the indicator of external competitiveness becomes more important than before, so my paper aims to know not only whether there is stochastic segmented trend in their fluctuation but also the factors which are closely related to regime switches. As we all know that it is significant to forecast the volatility of exchange rate in the global society. A number of previous studies discussed the relationship between exchange rate and fundamentals under the monetary models, however many people found that these models are handicapped in out-of sample forecasting. Therefore, I compare the forecasting performance of the real interest differential monetary (RID) model of Frankel (1979) with the models which I built in the paper. By using the market share of the top ten currencies in 2010 which is published by Bank for International Settlements (BIS) and the fundamentals. The empirical results indicate that fundamentals do not only matter for real exchange rate, but are also related to the switches between the regimes. Besides, the real exchange rates are highly persistent in each regime and the effect of fundamentals is different in different countries. At last, my result suggest that the models which I built in the paper provide better forecast in the yen, pound sterling and New Zealand dollar than the RID model.

Cette thèse résume les travaux concernant les essais de fiabilité des commutateurs RF MEMS capacitifs et ohmiques développé par le CEA-Leti.Dans le premier chapitre les mesures de raideur par la technique de nano-indentation sur des commutateurs MEMS réels sont complétées par des observations AFM, MEB et FIB pour expliquer le comportement électrique des différents lots de commutateurs de type ohmique.Le deuxième chapitre présente les résultats de la caractérisation des propriétés structurales et physiques des diélectriques, qui sont généralement utilisés dans nos commutateurs RF MEMS ohmiques et capacitifs. Les analyses élémentaires confirment que tous les nitrures SiNx et oxydes SiO2 fabriqués par la technique PECVD ont une qualité inférieure par rapport à leurs homologues synthétisés à haute température.Les mécanismes de conduction sont identifiés dans SiNx et SiO2 PECVD en mesurant des courbes I-V sur les condensateurs MIM. Pour les deux nitrures SiNx, qui sont déposés en haute (HF) et fréquence mixte (MF), le mécanisme de conduction de type Poole-Frenkel. Pour le SiO2 le mécanisme de conduction est plus susceptible d'être contrôlé par émission Schottky. Les mesures I-V révèlent que tous ces matériaux piègent des charges parasites, il y a en effet une forte hystérésis entre les parties aller et retour de la courbe I-V.Pour étudier la cinétique de piégeage de charge des condensateurs MIM sont utilisés. Pour identifier les propriétés des pièges la technique d'injection à courant constant est utilisée. Le diélectrique SiNx PECVD montre une dépendance logarithmique de la cinétique de piégeage, tandis que le SiO2 montre une dépendance exponentielle. La concentration totale de pièges ne montre aucune dépendance pour les SiNx HF et SiO2 MF, ou une dépendance faible en fonction du champ pour le SiNx MF. La section efficace de capture dépend du champ pour les deux types de nitrures, ce qui est cohérent avec le modèle de piégeage à effet répulsif. Pour le SiO2, où un modèle de piégeage du premier ordre a été utilisé, la section efficace de capture est indépendante du champ. Dans le chapitre 4, les dérives de tension expérimentales sont mesurées lors des tests de stress à tension constante, pour différents niveaux de contrainte de tension. Dans la partie suivante, nous proposons une approche originale de modélisation de la dérive de la tension de "pull-in" basée sur le mécanisme de conduction et les propriétés de piégeage des diélectriques. Nous démontrons que grâce a notre modèle, il est possible d'expliquer les dérives de tension mesurée en termes de propriétés diélectriques bien identifiées. Cette procédure donne des résultats simulés en bon accord avec les mesures pour tous les matériaux, et permet de prédire les résultats de n'importe quelle séquence de vieillissement électrique. Nous utilisons ensuite notre modèle pour étudier l'effet des propriétés diélectriques et de la conception du commutateur sur le comportement à long terme de nos commutateurs MEMS. / This thesis summarizes the work concerning reliability testing of electrostatic capacitive- and ohmic-type RF MEMS switches developed by the CEA-Leti. In the first chapter the measurement of stiffness by the nanoindentation technique on real MEMS switches are completed by AFM, SEM and FIB observations in order to explain the electrical behavior of different wafers of the ohmic-type switches. The second chapter presents the results of the characterization of the structural and physical properties of the dielectrics, which are typically used in our ohmic- and capacitive-type RF MEMS switches. Elemental analyses confirm that all SiNx and SiO2 samples fabricated by the PECVD technique have inferior quality compared to their high-temperature counterparts.The conduction mechanism are identified in PECVD SiNx and SiO2 by measuring I-V curves on MIM capacitors. For both SiNx materials, that is deposited in high- (HF) and mixed-frequency (MF) mode, the conduction process is controlled by Poole-Frenkel mechanism. For the MF SiO2 the conduction mechanism is most likely to be controlled by Schottky emission. The I-V measurements reveal, that all these materials are prone to trapping parasitic charge, which is observed as hysteresis between the ramp-up and ramp-down parts of the I-V curve.For studying the kinetics of charge trapping the MIM capacitors are used. To identify the trapping properties the constant current injection technique is used. The PECVD SiNx dielectric turns out to show logarithmic dependence of the trapping kinetics, while the SiO2 shows an exponential dependence. The total concentration of traps shows no field-dependence for the HF SiNx and MF SiO2 or weak field dependence for the MF SiNx sample. The capture cross section is field dependent for both samples with SiNx, which is consistent with the repulsive trapping model. For the SiO2, where the first order trapping model was used, the capture cross-section is not field dependent.In the chapter 4, experimental voltage drifts are measured during constant voltage stress tests for different voltage stress levels. In the following part we propose an original approach to modeling of the voltage drifts based on the identified conduction mechanism and trapping properties of the dielectrics. We demonstrate that thanks to our model it is possible to explain the measured voltage drifts in terms of the identified dielectric properties. The simulated results are in good agreement with experimental ones for all investigated materials and it allows to predict the voltage drift for any aging conditions. In the next step, we use our model to study the effect of the dielectric properties and the switch design on the long term behavior of RF MEMS switches.

During IgH class switch recombination (CSR) in mature B lymphocytes, activation-induced cytidine deaminase (AID) initiates DNA double strand breaks (DSBs) within switch (S) regions flanking different sets of the IgH locus (IgH) constant \((C_H)\) region exons. End-Joining of DSBs in the upstream donor S region (Sm) to DSBs in a downstream acceptor S region \((S_{acc})\) replaces the initial set of \(C_H\) exons, Cm, with a set of downstream \(C_H\) exons, leading to Ig class switching from IgM to another IgH class (e.g., IgG, IgE, or IgA). In addition to joining to DSBs within another S region, AID-induced DSBs within a given S region are often rejoined or joined to other DSBs in the same S region to form internal switch deletions (ISDs). ISDs were frequently observed in Sm but rarely in \(S_{acc}s\), suggesting that AID targeting to \(S_{acc}s\) requires prior recruitment to Sm. To test this hypothesis, we assessed CSR and ISDs in B cells lacking Sm and found that AID frequently targets downstream \(S_{acc}s\) independently of Sm. These studies also led us to propose an alternative pathway of "downstream" IgE class switching that involves joining of DSBs within the downstream \(S\gamma1\) and \(S\epsilon\) regions as a first step before joining of \(S\mu\) to the hybrid downstream S region. To further elucidate the CSR mechanism, we addressed the long-standing question of whether S region DSBs during CSR involves a direction-specific mechanism similar to joining of RAG1/2 endonuclease-generated DSBs during V(D)J recombination. We used an unbiased high throughput method to isolate junctions between I-SceI meganuclease-generated DSBs at a target site that replaces the IgH \(S\gamma1\) region and other genomic DSBs of endogenous origin. Remarkably, we found that the I-SceI-generated DSBs were joined to both upstream DSBs in \(S\mu\) and downstream DSBs in \(S\epsilon\) predominantly in orientations associated with joining during productive CSR. This process required the DSB response factor 53BP1 to maintain the orientation-dependence, but not the overall levels, of joining between these widely separated IgH breaks. We propose that CSR exploits a mechanism involving 53BP1 to enhance directional joining of DSBs within IgH in an orientation that leads to productive CSR.

La faune sauvage a été depuis longtemps incriminée dans la survenue de zoonoses et joue le rôle de réservoir d'agents pathogènes (virus Nipah, Hendra, Ebola, Hantaan etc.) pour l'homme. Les îles tropicales et subtropicales du Sud-Ouest de l'Océan Indien (SOOI) constituent l'une des 34 régions reconnues comme « hotspot » de biodiversité au niveau mondial. Elles sont caractérisées par un très fort endémisme de la faune sauvage surtout sur l'Ile de Madagascar. Le caractère multi-insulaire de la région du SOOI, la diversité de ses biotopes et ses disparités biogéographiques et humaines offrent un champ d'investigation unique pour explorer « in natura » la dynamique évolutive des agents infectieux et les relations hôtes-virus. Nos travaux de recherche ont porté sur deux modèles de virus à ARN de polarité négative, les paramyxovirus et les lyssavirus. Le premier modèle viral nous a permis d'aborder les questions relatives à la dynamique de transmission virale au sein de communauté d'hôtes, plus particulièrement, les chauves-souris et les petits mammifères terrestres de Madagascar et d'identifier les facteurs agissant sur cette dynamique de transmission et de diversification virale, en particulier les facteurs bio-écologiques associés à leurs hôtes. Le second modèle viral, les lyssavirus, nous a permis de décrire sur l'ensemble des îles du SOOI échantillonés, la circulation virale dans ce système multi-insulaire diversifié, au sein des chauves-souris dont la plupart des espèces sont endémiques à cette région. Dans l'ensemble, nos investigations ont permis de mettre en évidence des échanges viraux (« host-switch ») importants entre chauves-souris, petits mammifères terrestres endémiques de Madagascar et les rongeurs introduits, le rôle de ces mammifères en tant que réservoir viral majeur et souligner le rôle disséminateur de Rattus rattus. Par ailleurs, nous avons pu identifier ce phénomène de « host-switch » comme étant le mécanisme macro-évolutif prépondérant et l'importance des facteurs biotiques et abiotiques à l'origine de la dynamique de transmission et de la diversification virale observée chez les paramyxovirus de chauves-souris de Madagascar. / Since many decades, the wild fauna has been incriminated as an important reservoir of many zoonotic pathogens (Nipah, Hendra, Ebola, Hantaan viruses etc.) at risk for humans. Tropical and subtropical islands of the South West Indian Ocean (SWIO) are part of the 34 areas of the world recognized as "hotspot" of biodiversity. They are characterized by a strong wildlife endemism especially on Madagascar. The multi-island structure of the SWIO region, the diversity of its biotopes and its biogeographical human disparities, offer a unique opportunity to investigate "in natura" the evolutionary dynamics of infectious agents and the host-virus relationships. Our research has focused on two models of negative RNA viruses, paramyxoviruses and lyssaviruses. The first virus model allowed us to address issues related to the dynamics of viral transmission within a host community, in particular, bats and small terrestrial mammals of Madagascar and to identify the driving factors, especially bio-ecological factors associated with their hosts, affecting the dynamic of transmission and of viral diversification. The second model allowed us to describe on the islands of the SWIO, the intense circulation of bats lyssaviruses in this multi-island system which bats are endemic to this region. Overall, our investigations highlighted (i) intense viral exchanges ("host-switch") between bats, endemic terrestrial small mammals and introduced rodents from Madagascar, (ii) the role of these mammals as major viral reservoir and (iii) the key role played by Rattus rattus as viral spreader. Furthermore, we identified both the phenomenon of "host-switch" as the major macro-evolutionary mechanism among bat paramyxoviruses from Madagascar and the importance of biotic and abiotic factors in shaping the transmission dynamics and viral diversification.

Nanocrystalline diamond (NCD) due its outstanding thermal, mechanical and tribological properties is an ideal candidate for MEMS/NEMS devices. NCD offers the possibility to increase the reliability and life time of RF-MEMS switches and by mitigating the problems of stiction, charge trapping, surface wear and cold welding found in traditional all metal MEMS devices. In this work, nanocrystalline diamond cantilever beams and bridges have been fabricated on a low resistive silicon substrate by using standard micromachining techniques. The diamond structures are then integrated onto alumina and aluminium nitride substrates upon which microwave transmission lines in the microstrip and coplanar waveguide (CPW) topology have been fabricated. The diamond actuators are integrated using a combined soldering and flip chip technique. The NCD bridges are thermally actuated wherein the difference in coefficient of thermal expansion between copper and diamond bends the diamond bridge thus moving the bridges to the actuated state. In the CPW topology, RF-MEMS switches and tunable planar inductors are realized using the micromachined devices. These devices are mounted on a 650 micrometer thick alumina substrate and the microwave characteristics are analyzed in the frequency range of 5-30 GHz. The switches yield a return loss of 15 dB and an insertion loss of 0.2 dB at 20GHz. An inductance ratio of 2.2 is achieved by the tunable inductors at 30 GHz. High power measurements are performed on the diamond actuators which utilize a dual actuation scheme which comprises of thermal and electrostatic actuation. The measurements are performed on the diamond actuators in the power range of 24-47 dBm for the mechanically actuated switches, and 24-40 dBm for electrically actuated switches. The measurements show an insertion loss of 0.2-03 dB in the entire power spectrum. NCD based RF-MEMS capacitive switches is also designed, fabricated and tested. The switches are fabricated on a high resistive silicon substrate and are electrostatically actuated. Small signal measurements are presented in the frequency range of 1-65 GHz. The measured insertion loss in the up-state is 1.1 dB at 50 GHz with 30 dB isolation in the down-state. Dielectric characterization is performed using the Corona-Kelvin technique and the standard I-V and C-V stress tests for nitride and diamond films. The leaky nature of the diamond films provides a potential solution to reliability issues related to dielectric charging.