The work is focused on antennas integrated into the helmet. They preferred planar antennas with different polarization and different feed. They consider possible positions on the helmet, or into helmet.

Internet of Things (IoT) is a new emerging paradigm which requires billions of wirelessly connected devices that communicate with each other in a complex radio-frequency (RF) environment. Considering the huge number of devices, recharging batteries or replacing them becomes impractical in real life. Therefore, harvesting ambient RF energy for powering IoT devices can be a practical solution to achieve self-charging operation. The antenna for the RF energy harvesting application must work on multiple frequency bands (multiband or wideband) to capture as much power as possible from ambient; it should be compact and small in size so that it can be integrated with IoT devices; and it should be low cost, considering the huge number of devices. This thesis presents a fully printed 3D cube Cantor fractal RF energy harvesting unit, which meets the above-mentioned criteria. The multiband Cantor fractal antenna has been designed and implemented on a package of rectifying circuits using additive manufacturing (combination of 3D inkjet printing of plastic substrate and 2D metallic screen printing of silver paste) for the first time for RF energy harvesting application. The antenna, which is in a Cantor fractal shape, is folded on five faces of a 3D cube where the bottom face accommodates rectifying circuit with matching network. The rectenna (rectifying antenna) harvests RF power from GSM900, GSM1800, and 3G at 2100 MHz frequency. Indoor and outdoor field tests of the RF energy harvester have been conducted in the IMPACT lab and the King Abdullah University of Science and Technology (KAUST) campus territory, and 252.4 mV of maximum output voltage is harvested.

In the past decade we have seen fast development of new quantum technologies that promise to revolutionise communications and computing. Many different routes are explored to physically implement such quantum technologies. Among others, we can mention superconducting circuits, spin-based devices and photonic devices.  An active area of research concerns hybrid quantum systems, which aim at combining the best properties of these different implementations. Recently quantum acoustics has been gaining interest as a potential intermediate in such hybrid systems. Indeed, phonons can couple to many different degrees of freedom and could therefore form an interface between different quantum systems.One method to convert microwaves to an acoustic signal relies on the exploitation of the piezoelectric effect. However, for transducer devices based on the piezoelectric effect, the operating bandwidth has remained limited. By using tunable matching circuits, we propose a device capable of performing piezoelectric transduction over large bandwidths. The tunability is achieved by using SQUID transmission lines. This work reports some preliminary studies towards the creation of such a platform. We conduct measurements at cryogenic temperatures on suspended lithium niobate delay lines. These allow us to characterise the dependence of the IDT response on various parameters such as the number of fingers and the angle relative to the underlying crystal. We show that certain angles favour transduction into a single acoustic mode. In parallel, we characterise transmission lines consisting of one-dimensional arrays of SQUIDs. By applying magnetic flux to these lines, we show that it is possible to tune their impedance. These experiments improved our understanding of both IDTs and SQUID transmission lines and pave the way for the implementation of our experimental platform. / Under det senaste decenniet har vi sett en snabb utveckling av ny kvantteknologi som kommer att revolutionera telekommunikation och databehandling. Många olika vägar utforskas för att fysiskt realisera sådan kvantteknologi. Bland annat kan vi nämna supraledande kretsar, spinbaserade anordningar och fotoniska anordningar.  Ett aktivt forskningsområde är hybrida kvantsystem som kombinera de bästa egenskaperna hos dessa olika tillämpningar. På senare tid har kvantakustik fått ökat intresse som en potentiell mellansteg i sådana hybridsystem. Fononer kan kopplas till många olika frihetsgrader och skulle därför kunna fungera som ett gränssnitt mellan olika kvantsystem.En metod för att omvandla mikrovågor till en akustisk signal bygger på utnyttjandet av den piezoelektriska effekten. För transduceranordningar som bygger på den piezoelektriska effekten har dock den operativa bandbredden fortfarande varit liten. Genom att använda avstämbara anpassningskretsar föreslår vi en anordning som kan utföra piezoelektrisk transduktion över stora bandbredder. Avstämbarheten uppnås med hjälp av SQUID-överföringsledningar. I detta arbete rapporteras några preliminära studier för att skapa en sådan plattform. Vi utför mätningar vid kryogena temperaturer på upphängda fördröjningsledningar av litiumniobat. Dessa gör det möjligt för oss att karakterisera IDT-svarets beroende av olika parametrar, t.ex. antalet fingrar och vinkeln i förhållande till den underliggande kristallen. Vi har visat att vissa vinklar gynnar transduktion till ett enda akustiskt läge. Parallellt karakteriserar vi transmissionsledningar som består av endimensionella matriser av SQUIDs. Genom att applicera magnetiskt flöde på dessa linjer visar vi att det är möjligt att ställa in deras impedans. Dessa experiment förbättrade vår förståelse av både IDT:er och SQUID-överföringslinjer och banar väg för genomförandet av vår experimentella plattform.

No description available.

Yes / Matching the antenna’s impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna’s radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence (< 5 µs) and is highly accurate for autonomous adaptive antenna matching networks. / This work is partially supported by RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE), and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.

The batteries used to power wireless sensor nodes have become a major roadblock for the wide deployment. Harvesting energy from mechanical vibrations using piezoelectric cantilevers provides possible means to recharge the batteries or eliminate them. Raw power harvested from ambient sources should be conditioned and regulated to a desired voltage level before its application to electronic devices. The efficiency and self-powered operation of a power conditioning and management circuit is a key design issue. In this research, we investigate the characteristics of piezoelectric cantilevers and requirements of power conditioning and management circuits. A two-stage conditioning circuit with a rectifier and a DC-DC converter is proposed to match the source impedance dynamically. Several low-power design methods are proposed to reduce power consumption of the circuit including: (i) use of a discontinuous conduction mode (DCM) flyback converter, (ii) constant on-time modulation, and (iii) control of the clock frequency of a microcontroller unit (MCU). The DCM flyback converter behaves as a lossless resistor to match the source impedance for maximum power point tracking (MPPT). The constant on-time modulation lowers the clock frequency of the MCU by more than an order of magnitude, which reduces dynamic power dissipation of the MCU. MPPT is executed by the MCU at intermittent time interval to save power. Experimental results indicate that the proposed system harvests up to 8.4 mW of power under 0.5-g base acceleration using four parallel piezoelectric cantilevers and achieves 72 percent power efficiency. Sources of power losses in the system are analyzed. The diode and the controller (specifically the MCU) are the two major sources for the power loss. In order to further improve the power efficiency, the power conditioning circuit is implemented in a monolithic IC using 0.18-μ­m CMOS process. Synchronous rectifiers instead of diodes are used to reduce the conduction loss. A mixed-signal control circuit is adopted to replace the MCU to realize the MPPT function. Simulation and experimental results verify the DCM operation of the power stage and function of the MPPT circuit. The power consumption of the mixed-signal control circuit is reduced to 16 percent of that of the MCU. / Ph. D.

The proposed circuit intends to harvest kinetic energy from ElectroMagnetic Generators (EMGs). In order to extract maximum power from an EMG, an AC-DC boost rectifier is designed to match the impedance of the EMG. Rather than operate a buck-boost converter in Discontinuous Conduction Mode (DCM) in other impedance matching cases, the proposed method is running the boost topology in Boundary Conduction Mode (BCM). So it would perform resistive input matching, while reducing the converter power loss. The boost rectifier also merges a rectifier and a boost converter to reduce power loss for rectification. It also utilizes the internal inductance of the EMG to eliminate the impedance matching error and reduce the off-chip inductor size. An optional buck converter regulates the output voltage to 5 V to power devices through USB ports. The proposed circuit is designed and fabricated in BiCMOS 0.18 μm technology. Its functionality is shown through simulation results. The measurement of the IC is also performed. However, since the IC only work partially, test result is gathered using some discrete components as substitutes. It indicates the circuit can realize the proposed control method. / Master of Science / The development of energy-efficient semiconductor devices has reduced the power requirements of electronic circuits. As the electronics’ scale decreases, so does the energy consumption. In this sense, batteries were also produced in smaller size providing more energy storage availability. However, due to technical and technological issues, the batteries have not been followed by the same evolutionary trend limiting the operational time and performance of portable devices as it need to be recharged or replaced periodically. On the other hand, portable electronic devices such as cell phones, GPS, cameras, etc. are powered only by batteries. For circumstances that power supplies are not accessible, energy harvesting (EH) from human or environmental sources has proven to be an effective alternative or complement. Light, thermal, mechanical and RF are major sources in EH. Among them, mechanical energy from wind, waves, vibrations, etc. is commonly existed in our daily life. The energy is harvested by using micro generators and the various types include electromagnetic, piezoelectric and electrostatic. In particular, the ElectroMagnetic Generator (EMG) is of great interest for its potentially high energy density and efficiency. Since EMG is an AC voltage generator while portable devices usually require a stable DC supply, an EH circuit as a rectifier ought to be designed. At the same time, for EH application, we would like to harvest as much power as possible from EMGs. This research project addresses the development of a unique EH circuit capable of fulfilling the distinct needs illustrated above.

Les étiquettes d'identification radiofréquence passifs (RFID) sont des systèmes télé-communiquant dont l'approvisionnement en énergie se fait via les ondes électromagnétiques. De plus en plus présents dans notre environnement (passeport, badge d'accès, gestion de stock), ils ont l'avantage d'avoir une durée de vie presque infinie, et ne consomment de l'énergie que lorsqu'ils sont sollicités. Par ailleurs, leur moyen de communiquer, sans fil, permet de les utiliser dans des endroits difficiles d'accès pour des lecteurs optiques type code à barre. Toutefois, la portée de tels systèmes est limitée par l'efficacité de la récupération de l'énergie provenant des ondes. Dans ce cadre, l'augmentation de la portée des étiquettes RFID, notamment pour les applications de logistique est un élément primordial.Sont présentés dans cette thèse différents moyens d'augmenter cette portée notamment grâce à l'amélioration des blocs de récupération d'énergie ou l'adaptation d'impédance, tout en respectant des contraintes liées au coût du système. La première partie se focalise sur la réduction des pertes du bloc de récupération d'énergie par l'optimisation du layout. Une architecture à haut rendement à transistor polarisé est ensuite proposée. Pour finir, l'impact de la rétro-modulation et de l'adaptation d'impédance en fréquence sur la récupération d'énergie sont étudiés et améliorés. / The passive radio frequency identification tags (RFID) systems communicate with a remote power supply thanks to electromagnetic waves. Increasingly present in our environment (biometric passport, inventory management), they present the advantage to have an almost infinite lifetime, and consume energy only when they are solicited. Moreover, because it is a wireless way to communicate, it is possible to use these systems places inaccessible to optical drives type bar code. However, the range of such systems is limited by the efficiency of the recovery of energy from waves. In this context, increasing the range of RFID tags, especially for logistics applications is essential.In this these, different ways to increase the range are studied. The first part focuses on the reduction of losses on the rectifying circuitry thanks to layout optimization. An high performances architecture with transistor biased is then proposed. Finally, the impact of backscattering and impedance matching on the energy recovery are studied and improved.

Le contexte de la thèse se situe sur le marché du NFC, des cartes sécurisées ainsi que du paiement sans contact qui sont en forte croissance ces dernières années. L’objectif est de développer un environnement de simulation afin de concevoir différents dispositifs NFC destinés à des produits nomades comme un smartphone ou une tablette tactile et qui répondent aux différentes normes NFC. / The thesis context is focused on the NFC market, secure cards and contactless paiement which are in strong development in recent years. The objective is to develop a simulation environment to design NFC features for mobile devices as smartphone or tactile tablet which satisfy NFC standards.

With  the  continuous  advances  in  microwave  technology,  microwave  components  and  related magnetic materials become more important in industrial environment. In order to further develop the microwave components, it is of interest to find new kinds of technologies and materials. Here, we  introduce  a  new  kind  of  material  --  amorphous  metallic  wires  which  could  be  used  in microwave  components,  and  use  these  wires  to  design  new  kinds  of  attenuators.  Based  on  the fundamental  magnetic  properties  of  amorphous  wires  and  transmission  line  theory,  we  design  a series of experiments focusing on these wires, and analyze all the experimental results.    Experimental  results  show  that  incident  and  reflected  signals  produce  interference  and  generate standing  waves  along  the  wire.  At  given  frequency,  the  insertion  attenuation  S21 [dB]  of  an amorphous wire increases monotonically with dc bias current. The glass cover will influence the  magnetic  domain  structure  in  amorphous  metallic  wires.  Therefore,  it  will  affect  the circumference  permeability  and  change  the  signal  attenuation.  It  is  necessary  to  achieve  the impedance  matching  by  coupling  to  an  inductor  and  a  capacitor  in  the  circuit.  The  impedance matching  makes  the  load  impedance  close  to  the  characteristic  impedance  of  transmission  line. The magnetic wire-based attenuator designed in this thesis work are characterized and compared to conventional pin-diode attenuator.