Dissertations / Theses on the topic 'Rectenna design'

Miniaturisation has been the holy grail of mobile technology. The ability to move around with our gadgets, especially the ones for communication and entertainment, has been what semiconductor scientists have battled over the past decades. Miniaturisation brings about reduced consumption in power and ease of mobility. However, the main impediment to untethered mobility of our gadgets has been the lack of unlimited power supply. The battery had filled this gap for some time, but due to the increased functionalities of these mobile gadgets, increasing the battery capacity would increase the weight of the device considerably that it would eventually become too heavy to carry around. Moreover, the fact that these batteries need to be recharged means we are still not completely free of power cords. The advent of low powered micro-controllers and sensors has created a huge industry for more powerful devices that consume a lot less power. These devices have encouraged hardware designers to reduce the power consumption of the gadgets. This has encouraged the idea of wireless power transmission on another level. With lots of radio frequency energy all around us, from our cordless phones to the numerous mobile cell sites there has not been a better time to delve more into research on WPT. This study looks at the feasibilities of WPT in small device applications where very low power is consumed to carry out some important functionality. The work done here compared two rectifying circuits’ efficiencies and ways to improve on the overall efficiencies. The results obtained show that the full wave rectifier would be the better option when designing a WPT system as more power can be drawn from the rectenna. The load also had a great role as this determined the amount of power drawn from the circuitry.

Thesis (M.S. in Combat Systems and Technologies)--Naval Postgraduate School, December 2005.
Thesis Advisor(s): David C Jenn, Richard Harkins. Includes bibliographical references (p.119-122). Also available online.

Various nondestructive testing (NDT) technologies for construction and performance monitoring have been studied for decades. Recently, the rapid evolution of wireless sensor network (WSN) technologies has enabled the development of sensors that can be embedded in concrete to monitor the structural health of infrastructure. Such sensors can be buried inside concrete and they can collect and report valuable volumetric data related to the health of a structure during and/or after construction. Wireless embedded sensors monitoring system is also a promising solution for decreasing the high installation and maintenance cost of the conventional wire based monitoring systems. Wireless monitoring sensors need to operate for long time. However, sensor batteries have finite life-time. Therefore, in order to enable long operational life of wireless sensors, novel wireless powering methods, which can charge the sensors’ rechargeable batteries wirelessly, need to be developed. The optimization of RF wireless powering of sensors embedded in concrete is studied here. First, our analytical results focus on calculating the transmission loss and propagation loss of electromagnetic waves penetrating into plain concrete at different humidity conditions for various frequencies. This analysis specifically leads to the identification of an optimum frequency range within 20-80 MHz that is validated through full-wave electromagnetic simulations. Second, the effects of various reinforced bar configurations on the efficiency of wireless powering are investigated. Specifically, effects of the following factors are studied: rebar types, rebar period, rebar radius, depth inside concrete, and offset placement. This analysis leads to the identification of the 902-928 MHz ISM band as the optimum power transmission frequency range for sensors embedded in reinforced concrete, since antennas working in this band are less sensitive to the effects of varying humidity as well as rebar configurations. Finally, optimized rectennas are designed for receiving and/or harvesting power in order to charge the rechargeable batteries of the embedded sensors. Such optimized wireless powering systems exhibit significantly larger efficiencies than the efficiencies of conventional RF wireless powering systems for sensors embedded in plain or reinforced concrete.

The great innovations of the last century have ushered continuous progress in many areas of technology, especially in the form of miniaturization of electronic circuits. This progress shows a trend towards consistent decreases in power requirements due to miniaturization. According to the ITRS and industry leaders, such as Intel, the challenge of managing and providing power efficiency still persist as scaling down of devices continues. A variety of power sources can be used in order to provide power to low power applications. Few of these sources have favorable characteristics and can be designed to deliver maximum power such as the novel mini notched turbine used as a source in this work. The MiNT is a novel device that can be used as a feasible energy source when integrated into a system and evaluated for power delivery as investigated in this work. As part of this system, a maximum power point tracking system provides an applicable solution for capturing enhanced power delivery for an energy harvesting system. However, power efficiency and physical size are adversely affected by the characteristics and environment of many energy harvesting systems and must also be addressed. To address these issues, an analysis of mini notched turbine, a RF rectenna, and an enhanced maximum power point tracking system is presented and verified using simulations and measurements. Furthermore, mini notched energy harvesting system, RF rectenna energy harvesting system, and enhanced maximum power point tracking system are developed and experimental data analyzed. The enhanced maximum power point tracking system uses a resistor emulation technique and particle swarm optimization (PSO) to improve the power efficiency and reduce the physical size. This new innovative design improves the efficiency of optimized power management circuitry up to 7% compared to conventional power management circuits over a wide range of input power and range of emulated resistances, allowing more power to be harvested from small energy harvesting sources and delivering it to the load such as smart sensors. In addition, this is the first IC design to be implemented and tested for the patented mini notched turbine (MiNT) energy harvesting device. Another advantage of the enhanced power management system designed in this work is that the proposed approach can be utilized for extremely small energy sources and because of that the proposed work is valid for low emulated resistances. and systems with low load resistance Overall, through the successful completion of this work, various energy harvesting systems can have the ability to provide enhanced power management as the IC industry continues to progress toward miniaturization of devices and systems.

L'amélioration de l'autonomie énergétique des systèmes communicants constitue aujourd'hui une des préoccupations majeures pour leur déploiement massif dans notre environnement. On souhaite rendre complètement autonome ces dispositifs électroniques (on pense entre autres aux capteurs et réseaux de capteurs) en s'affranchissant des sources d'énergie embarquées qui nécessitent des opérations de remplacement ou de recharge périodiques. Parmi les sources d'énergie disponibles qui peuvent être exploitées, on trouve les ondes électromagnétiques. Le dispositif qui permet de capter cette énergie et la convertir en puissance continue utile est dénommé Rectenna (Rectifying antenna) qui associe une antenne de captation à un circuit de rectification à base de diodes. Les rectennae ont fait l'objet d'un nombre important de communications dans la littérature ces dernières années avec pour fil conducteur, la recherche de performances optimales compte tenu de l'atténuation des ondes électromagnétiques et des faibles niveaux de champ récupérés. C'est dans ce contexte que s'est déroulé ce travail de thèse dont le financement a été assuré par un contrat ANR (REC-EM).Dans ce travail, on s'est attaché à développer, à concevoir et à caractériser expérimentalement des structures planaires qui présentent des propriétés intéressantes :- En terme de polarisations orthogonales, ceci de façon à s'affranchir de l'orientation arbitraire de l'onde incidente à la rectenna. Une rectenna à double polarisation circulaire à 2.45 GHz et à double accès sera réalisée pour, de plus, s'affranchir de la perte de 3 dB lorsque l'onde récupérée est à polarisation linéaire à orientation arbitraire.- En termes de résonances multiples, ceci pour augmenter le niveau de puissance récupérée par l'antenne et optimiser la puissance continue convertie. Une rectenna à double fréquence (1.8 et 2.45 GHz) et à accès unique sera conçue ainsi qu'une rectenna constituée d'un réseau de deux antennes double fréquence.- En terme de réduction de taille en s'affranchissant de l'utilisation du filtre HF entre l'antenne et le circuit de conversion ceci pour l'ensemble des structures rectennae développées dans ce travail. Dans tous les cas, il sera nécessaire de développer le circuit de rectification le plus adapté à la topologie de l'antenne de captation et évaluer la technique de recombinaison optimale coté DC pour s'affranchir au mieux des déséquilibres qui peuvent apparaître entre les voies d'accès de l'antenne. Pour contenir les dimensions de la structure globale, des circuits mono diode seront dimensionnés et réalisés pour chacune des structures. Enfin, on exploitera l'antenne à double polarisation circulaire double accès, dont on cherchera à diminuer les dimensions, pour alimenter un capteur de température à affichage LCD. Pour augmenter le niveau de tension nécessaire au fonctionnement du capteur, nous associerons entre la rectenna et le capteur un convertisseur DC-DC. Il s'agit, dans ce cas, d'un dispositif de gestion d'énergie adapté pour les faibles puissances. Deux convertisseurs seront employés dont celui développé par les laboratoires Ampère de l'Ecole Centrale de Lyon et SATIE à l'ENS Cachan. Ce convertisseur a fait l'objet d'une thèse également financée par l'ANR dans le cadre de ce contrat REC-EM
Improving energy autonomy of communication systems constitutes one of the major concerns for their massive deployment in our environment. We want to make these electronic devices (sensors and sensor networks) completely autonomous, avoiding the embedded energy sources that require replacement operations or periodic charging. Among the available energy sources that can be harvested, there are electromagnetic waves. The device that can capture this energy and convert it into useful DC power is called Rectenna (Rectifying antenna), combining antenna with diode-based rectifier. In recent few years, rectennas have reached a significant number of papers in the literature. The main challenge consists in improving performances in term of efficiency, in an attempt to overcome the electromagnetic wave attenuation and the low available field level. According to this context, this PhD work supported by the ANR project REC-EM has taken place. In this study, we have developed, designed and characterized planar structures that have interesting properties:- In term of orthogonal polarizations, so energy harvesting becomes feasable regardless the arbitrary orientation of the incident wave on the rectenna. A dual-circularly polarized rectenna at 2.45 GHz with dual-access will be set up to overcome the 3 dB power loss in the case of linearly-polarized incident wave with unknown orientation.- In term of multiple resonances, so the amount of total RF power collected by the antenna can be increased and consequently the converted DC power level can also be improved. A dual-frequency rectenna (1.8 and 2.45 GHz) with single access will be designed, as well as a rectenna based upon a dual-frequency antenna array.- In term of size compactness by avoiding the use of the HF filter between the antenna and the rectifier for all developed rectenna structures during this work. In all cases, it will be necessary to define the most suitable rectifier topology to each antenna and select, if it is appropriated, the optimum DC recombination technique to overcome the effects of RF power imbalance that may occur between the different antenna accesses. Besides, single-diode circuits will be designed and fulfilled for each structure. Finally, we will miniaturize the dual-circularly polarized dual-access antenna, and exploit it to power a LCD display temperature sensor. To enhance the DC voltage level required to activate the sensor, a DC-DC converter is inserted between the rectenna and the sensor. Such energy management device should be able to operate under low delivered DC power. Two converters will be used. The first one is developed by Ampere Lab at Ecole Centrale de Lyon and SATIE Lab at ENS Cachan. This converter was the subject of another dissertation also supported by the ANR under the REC-EM project

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Bachelors
Engineering and Computer Science
Electrical Engineering

碩士
國立臺北科技大學
電腦與通訊研究所
100
This thesis proposes operating at 2.45GHz microwave frequency band high-efficiency rectifier circuit, which has the advantages of small, low-cost, material easy to obtain and etc. The rectifier circuit design uses nonlinear RF Schottky diode, microstrip transmission line impedance conversion principle, with the use of microstrip circuit to achieve low-pass filter and matching network functions. We use preliminary design of the rectifier circuit simulated on Agilent ADS 2009 as the practical circuit, and high-frequency signal is rectified into DC power by this circuit. As for the receiving antenna, we use Ansoft HFSS 11 to do the simulation for the high-directivity microstrip 2 x 2 antenna array, and as the reference of the practical receiving antenna. The proposed rectenna (integration of rectifier and array antenna) architecture is to achieve the 2.45GHz microwave power transmission applications. The realized 2 x 2 microstrip array antenna directivity is up to 12.49dBi; the realized LPF has been fed to high-efficiency rectifier circuit with fixed load 390Ohm to achieve the circuit conversion efficiency of 76.2% and the output voltage of up to 5.45 V when input power is 100mW. The 2x2 array rectenna could achieve the best conversion efficiency of 87.8% and the output voltage of 1.28V with the distance of 1.4 meter with the transmitter when the input power of transmitter is 316mW.

碩士
國立臺北科技大學
電腦與通訊研究所
101
In this thesis, dual polarized rectenna for the applications of wireless power transmission has been studied. The proposed antenna is operating at microwave frequency which intercepts and receives the RF energy of any polarization wave in free space. Design of the matching network and half-wave voltage doubler rectifier circuits by using the chip components to achieve impedance matching in antenna and rectifying circuit, can also effectively suppress the high order harmonics and down size the circuit size. The overall output DC voltage and conversion efficiency of the designed dual-polarized antenna with a rectifier circuits are measured. The dual-polarized antenna impedance bandwidth meets the specification of ISM(5.725~5.85GHz) and the measured peak gains of the antenna are 6.7~8.3dBi. For the proposed rectenna, the first port maximum voltage is 8.5 volts, the second port maximum voltage is 8.12 volts, and the overall system conversion efficiency up to 86%. The design of the second single-fed 5.8GHz dual-polarized antenna impedance bandwidth meets the specification of ISM(5.725~5.85GHz) and the measured peak gains of the antenna are 4.5~5.7dBi. For the proposed rectenna, the maximum dc voltage and effiency are respectively equal to 79% and 7.38 volts.

碩士
國立清華大學
電機工程學系
102
Rectenna is an important receiving circuit in wireless power transmission system. It can receive microwave power from antenna part and then transmit it to rectifier part for rectifying to direct current power. Therefore, rectennas can be widely used such as wireless power supply. In the following thesis, rectenna is divided into two main structures, antenna and rectifier, for more detail discussed. Part I describes FR4-fabricated quasi-yagi antenna which is fed by microstrip line. This kind of antenna, which is a development of dipole antenna, has a simple and easy understood structure. It utilizes reflect element and direct element to make its radiation pattern become narrower; therefore, its directivity and gain of quasi-yagi antenna can be higher. However, in order to narrow down the Half Power Beam-width of antenna, and improve antenna gain, quasi-yagi antenna array is proposed by using Wilkinson Power Divider. The gain pattern of antenna array can be calculated and is predictable with array factor. In this way, quasi-yagi antenna array can improve its directivity and gain to a higher level, and surely have a narrower Half Power Beam-width. The quasi-yagi antenna and its combination with Wilkinson power divider can be applied to wireless network system in the frequency of 2.4 GHz. The design process and measured results are shown in the end of Part I. Part II introduces FR4-fabricated rectifier including three different structures on purpose, and rectenna, which is composed of rectifier and antenna. Rectifiers can be separated into two types, 1-stage and 2-stage voltage multiplier. There are two different 1-stage voltage multiplier structures due to its well-matched point at different input power. Transition efficiency can be improved with match at higher input power. Besides, high input power can turn on diodes in 2-stage voltage multiplier so that it can acquire higher output voltage and efficiency. The last structure, rectenna, can not only transform microwave signal to direct signal providing to the following circuits but also measure antennas’ radiation pattern.

碩士
國立宜蘭大學
電子工程學系碩士班
106
The thesis aims at designing wearable low-power RF energy harvesting rectenna for healthcare, monitoring or the sensor on the human body. The rectenna has a rectifier and a patch antenna which is linear-polarized. The harvester was operated in the 2.45 GHz band and the 5.8 GHz band to capture the electromagnetic radiation energy. The choice of fabric and the electrical properties of the material are very important due to design for wearable devices. The wearable textile material we selected for on-body applications is cordura fabric. Using Schottky diodes to design a RF/DC rectifier, and utilizing ADS simulator to simulate the designed circuit, impedance matching between the rectifier and the half wavelength patch antenna were performed to achieve maximum power transferring. The rectifier is a single-stage full-wave Greinacher rectifier where we added a radio frequency choke (RFC) to isolate the influence of the load on the input RF signal. Traditionally, different loads will result in different impedance mismatch so that it results in a small output voltage. However, the resonant frequency is relatively stable in our case after adding the RF chokes. The output DC voltage of the 2.45 GHz rectenna can achieve 2.2 volts, while the 5.8 GHz rectenna can achieve 1.9 volts when the RF power is swept from -40 dBm to 0 dBm. The top surface of the rectifier is directly attached to the human body but our body is a lossy media. The study finds that the foam with copper foil added on the top surface of the rectifier helps to isolate the body-proximity effect on the rectifier. A TOTOLINK's AC1200 WiFi router was utilized as a WiFi radiation source in the indoor environment. The measurement results shows the foam has the feature of good isolation. The size of the rectenna measures only 80 × 80 × 2.2 mm. In addition to discussing how to match with a single-element rectenna, the rectenna is extended to a 2×2 rectenna array for generating sufficient DC power. The power transmission distance of the 2×2 array rectenna is from 60 cm to 150 cm. The output voltage is preserved between 1 volt and 3 volts. When the isolation S21 between the antenna and the antenna is less than -25 dBm, the minimum size is only 160 × 130 × 2.2 mm. The size is small enough to suitably paste on the back of the human body. Assuming a load of 1 MΩ, the maximum efficiency of the single element 2.45 GHz rectenna is only 10%, but the maximum efficiency of the 2×2 array rectenna can increase to 35%, reaching the best efficiency rectenna design that we expected.

碩士
國立虎尾科技大學
光電與材料科技研究所
97
In this research, the first part is to propose an implantable antenna with bandwidth enhancement and size reduction for medical implant communication service (MICS) biotelemetry application. This proposed MICS antenna utilizes a three-layer stacked probed structure to realize a center resonance located at the 402-405 MHz frequency band. By using the microwave substrate with a high dielectric constant of permittivity = 10.2 to reduce the structure of antenna, two MICS antennas including a circular stacked planar inverted-F antenna (PIFA) with a size of 5 × 5 × π × 1.905 mm3 and a square stacked planar inverted-F antenna (PIFA) with a size of 8 × 8 × 1.905 mm3 have been proposed. The return losses were measured by putting the designed antenna into the human simulating fluid with a permittivity εr of 46.7 and a conductivity σ of 0.69 S/m, which was made by properly mixing the sugar, salt and deionized water. The resonant modes of two antenna structures are excited at 404 MHz and 402 MHz, and have bandwidths of 84 MHz and 122 MHz, respectively, to cover the MSIC standard. The second part is focused on the application of the antenna for biotelemetry. To tackle the problem of the power supply for a body implantable device, the RF rectify circuit can be designed and adapted to the antenna to thus form a rectenna for charging the device. For the proposed design, the Schottky diode (HSMS-282C) was used to realize the retify circuit. The voltage and transform effency at the load for this circuit was also investigated when applying the Agilent RF signal generator (N9310A) as the power source.

碩士
國立臺北科技大學
電腦與通訊研究所
102
A broadband dual-polarized microstrip array antenna designed is proposed. To achieve wide 10 dB bandwidth for broadband operation, the technique of applying a ladder-shaped monopole antenna type with a rectangular slot insertion in the ground plane is implemented.The proposed design showed wide impedance bandwidth of the 1702-2755 MHz (47.2%). In addition, loading an open slot into the rectangular radiating element with an asymmetric ground plane was used and resulted in a slightly displacement of the radiation pattern. The 1 × 2 array type for two ladder-shaped patch array elements are arranged in symmetric feed network. By meticulously arrangement the two array antennas’ positions to achieved good ports isolation, with 10 dB bandwidth for the operating bands in free-space can be achieved. This antenna was used as a rectenna (rectifying antenna), which receives the RF energy of vertical and horizontal polarization wave in free space for 2.4 GHz wireless powering transmission. The rectifier circuit setup using two zero biased rectifier and voltage doubler circuit. A matching network designed with small size chip components have a significant improvement in impedance matching and eliminate high order harmonics between the antenna and rectifying circuit. The proposed dual-polarized rectenna provided the RF-to-DC conversion efficiency as high as 78.8% when 14 dBm microwave power was received at 2.4 GHz with a 1 KΩ load.

碩士
國立交通大學
電信研究所
83
The main target of this thesis is to make a Ka-band video rectenna by printed wire antenna associate with a rectifier. When we want use to a higher frequency band, the importance of power source is the same as the receiver. This receiver change the RF signal energy into DC output power. At first, a full- wave numerical analysis method is used to simulate the characteristics of a wire printed dipole antenna, a best radiation efficiency was obtained under controlled factors. we treat a wire printed dipole antenna as a Hertzian dipole on the substrate. The Green's function is obtained by image theory, then put it into Pocklington's equation, it becomes an integral- solving problem. Method of moment is used to obtain an integral- solving solution by a matrix form. Finally, we can get the current distribution of the antenna, and calculated the input impedance, and the effect of substrate on the radiation efficiency. Using this Ka-band dipole antenna with a rectifier, we design an quasi-optical receiver. Due to the limitation of the power, we put the rectenna in a waveguide, in order to measure the rectenna efficiency. The best transfer efficiency reach 27% when there is 18dBm energy incident on to the printed dipole. When a 10mA current bias on the diode, the sensitivity of the detector is 82mV/mW at -7dBm input power level. Finally, many improve methods and the directions of future study are given.

Microstrip patch antennas are the most common type of printed antenna due to a myriad of advantages which encourage use in a wide range of applications such as: wireless communication, radar, satellites, remote sensing, and biomedicine. An initial design for a stacked-patch, broadband, dual-polarized, aperture-fed antenna is tested, and some adjustments are made to improve performance. The design goal is to obtain a 3 GHz bandwidth centered at 10 GHz for each polarization. Once the single-element design is finalized, it is used in a 4x1 array configuration. An array increases the gain, and by utilizing variable phase-shifters to each element, the pattern can be electronically steered in a desired direction. The phase-can be easily adjusted. The result of this new phased array design is a wide bandwidth system with dual-polarization which can be electronically steered. Rectennas (rectifying antennas) are used in wireless power transmission (WPT) systems to collect microwave power and convert this power into useable DC power. They find use in many areas such as space power transmission, RFID tags, wireless sensors, and recycling ambient microwave energy. The ability to simulate rectenna designs will allow for an easier method of analysis and tuning without the time and expense of repetitive fabrication and measurement. The most difficult part of rectenna simulation is a good diode model, and since different diodes have dissimilar properties, a model must be specific to a particular diode. Therefore, a method of modeling an individual diode is the most critical part of rectenna simulation. A diode modeling method which is based on an equivalent circuit and compatible with harmonic balance simulation is developed and presented. The equivalent circuit parameters are determined from a series of S-parameter measurements, and the final model demonstrates S-parameters in agreement with the measured data. An aperture-coupled, high-gain, single-patch rectenna is also designed and measured. This rectenna is modeled using the presented method, and the simulation shows good agreement with the measured results. This further validates the proposed modeling technique.

碩士
國立臺北科技大學
電腦與通訊研究所
99
In this thesis, circularly polarized array rectenna for the applications of wireless power transmission has been studied. The proposed array antenna is operating at Microwave Frequency which intercepts and receives the RF energy of any polarization wave in free space. Low-pass filter, matching network and voltage-doubler rectifier are designed for impedance matching after the receiver antenna as well as to suppress the high order harmonics efficiently and minify the circuit size. It also solved the problem of traditional electric products battery charging. The technology of wireless power transmission for a rectenna by using the electromagnetic power as a charging resource, combine with the circular polarized array rectenna to achieve self-sufficiency application. The proposed design of circular polarized slot array antenna, Low-pass filter, matching network and the voltage-doubler rectifier which exhibit bandwidth and axial ratio bandwidth are following the specification of IEEE 802.11b (2.4~2.485 GHz). The result of the antenna gain is about 6~7.2 dBi. With the present design, a maximum voltage of 6.5 V and a conversion efficiency of 70 % colud be attainable.

碩士
國立臺北科技大學
電腦與通訊研究所
100
This paper presents a dual circular polarized rectenna structure with harmonic rejection filter to receive 2.45 GHz WLAN (IEEE802.11b) system for Wireless Power Transmission(WPT). The proposed rectenna is suitable for the subject of wireless receiving, the receiving RF energy is converted to DC in order to charge the rechargeable battery for the purpose of wireless charge. In this paper, proposed a dual-circular polarization filter rectenna for work in 2.45 GHz WLAN system. The structure can be divided into two parts of the design of the antenna and rectifier circuit. The first part of microstrip antenna for the main design, which are fed into pairs of microstrip coupled with open stub that achieve the purpose of the dual-circular polarization, impedance matching, and resonant filter, the design of slot on the ground plane, to reach 2.45 GHz band receiver, the antenna size is 100×100×3.7 mm3 The second part is the design of the rectifier circuit, the receiving RF energy which in front of the antenna, through the rectifier circuit can convert to DC output. The output of DC power can charge the rechargeable battery. While the input power is 22 dBm and the rectifier circuit load is 1000 Ω, the overall rectifier circuit in the 2.45 GHz band through the measurement of the maximum conversion efficiency and output voltage of 81.94 % and 11.45 V, respectively. The measured result shows a good performance for the WPT application.

碩士
國立交通大學
電機學院電信學程
107
This thesis studies the design of half-wave and full-wave rectennas for 900MHz~2.4GHz wireless power transfer. The overall system consists of: (1) PIFA antenna, (2) RF energy-to-DC power supply circuit consisted of balanced and unbalanced converter, matching network, half-wave and full-wave rectifier circuit and RF Schottky diode, and (3) DC-TO-DC charge-pump boost circuit. Experimental results show that the overall system developed can reach a dc output of 8.48V (without antenna) at 2.45GHz. With a load resistance of 470Ω and an injected power of 12dBm, the peak conversion efficiency is 88.24% with antenna and 85.75% without antenna. The 900MHz dc voltage output can reach up to 8.41V (without antenna). With a load resistance is 470Ω and an injected power of 12dBm, the peak conversion efficiency is 89% with antenna and 79.32% without antenna.

博士
國立成功大學
系統及船舶機電工程學系
103
This dissertation presents a broadband circularly polarized rectifying antenna (rectenna) for microwave power transmission at 4.2-7.6 GHz, comprising a broadband circularly polarized (CP) antenna and a rectifier circuit. This antenna finds its application for C band (4 to 8 GHz) that can receive more microwave power at different frequency. Moreover, the designed rectenna can be further researched to combine with microwave switch circuit for data communications. The CP antenna consists of an improved Schiffman phase shifter with easy implementation and use to provide a wideband phase difference of 90°. It also includes a pair of orthogonally positioned linearly polarized (LP) slot antennas with equal radiation strength that are used to accomplish a circular polarization by combining the horizontally and vertically polarized waves with a Wilkinson power divider. The proposed rectenna has an improved design and implementation using a broadband CP antenna that features a size reduction, good axial-ratio bandwidth and good return loss bandwidth. In addition, the rectifier circuit is composed of a microwave Si Schottky detector diode (HSMS-2862), a low-pass filter, a load resistor and a bypass capacitor. The output dc voltage of 1.98 V over a 680 Ω load resistance and the maximum microwave-to-dc conversion efficiency of 81.6 % were measured when a 34-dBm microwave power was transmitted at 5.6 GHz over a distance of 50 cm which was referred as the far field. The designed rectenna was printed on a double-sided FR4 substrate of thickness 1.6 mm with dielectric constant 4.4 and the simulation tools used in this study include Microwave office, Matlab, and Ansys HFSS.

碩士
北台灣科學技術學院
機電整合研究所
98
The rectifying antenna (Rectenna) is widely used in recent years, such as access control cards, MRT EasyCard and contactless charger. In this thesis, Agilent ADS software is used to simulate and compare the converted efficiency in several rectify circuit, such as voltage-double rectification, half-wave rectification, half-wave rectification with filter and the bridge rectification. The converted efficiency is defined by the ratio of RF power to DC voltage. When input power is applied 13dBm at 2.4GHz, the simulated results of the voltage-double rectification circuit, half-wave rectification circuit, half-wave rectification with filter circuit and the bridge rectification are 3.671V, 1.814V, 1.821V and 0.501V respectively. And the measured results are 5.55V, 2.36V, 3.01V and 2.63V. From the results of this study, the converted efficiency can be increased dramatically by using the voltage-double circuit.

碩士
國立臺北科技大學
電腦與通訊研究所
98
In this thesis, dual-band circularly polarized rectennas for the applications of wireless power transmission have been studied. The proposed design of dual-band circularly polarized antenna operating at 2.45/5.8 GHz can interception and receive the RF energy of random polarization in free space. Low-pass filter and dual-band matching network are designed for impedance matching between the receiver antenna and voltage-doubler rectifier as well as to suppress the higher order harmonics efficiently. The circularly polarized antenna and matching network for voltage-doubler rectifier, measured output voltage with conversion efficiency are also studied in the thesis. The designed dual-band circularly polarized antenna and matching network voltage-doubler rectifier circuit exhibit bandwidth and axial ratio bandwidth meet that can the specification of IEEE 802.11b (2.4~2.485 GHz) and IEEE 802.11a (5.725~ 5.825 GHz). The result of the antenna gain is about 3.5~6 dBi. With the present design, a maximum voltage of 5.4 V with a conversion efficiency up to 55% is attainable.

碩士
國立高雄大學
電機工程學系碩博士班
105
This thesis is mainly focused on the design of half wave and full wave voltage doubler circuits for wireless power transmission with an operating frequency of 2.45 GHz. First, a circularly polarized microstrip antenna is chosen to use, which can capture arbitrary polarized electromagnetic waves in free space with the characteristics of circular polarization. Second, matching impedance matching circuit design, effectively reduce the overall size of the circuit and complete the maximum power transmission. Finally, according to the rear end of a voltage doubler rectifier circuit, select the specific specifications of the Schottky diode in order to enhance the output DC voltage and conversion efficiency. The 2.45 GHz circularly polarized microstrip antenna, matching network, half wave and full wave voltage doubler rectifier circuit are designed in this paper. The whole structure can be divided into two parts, which are front antenna circuit and back end rectifier circuit. In the first part, microstrip antenna is used as the front end antenna of this paper. The characteristics of the cutting angle are used to achieve the perturbation surface current path, and the circular polarization characteristics are achieved. The second part is the back end rectifier circuit. Through the rectifier part, the RF energy collected by the front-end receiving antenna can be converted to DC voltage energy output. The antenna and circuit integrate the whole system, and the maximum voltage of the received half wave circuit can reach 2.5V, and the system conversion efficiency is up to 30%. The maximum voltage of the full wave circuit can reach 2.98V, and the system conversion efficiency is up to 37.79%.

碩士
國立成功大學
奈米科技暨微系統工程研究所
96
A design of wireless powering system (WPS) for biomedical application is presented in this thesis. The article is composed of two major topics. One is the WPS design in far-field application. The other is the WPS design in near-field application. First, we studied the WPS design in far-field applications which the key component is rectenna. Rectenna contains two units, far-field antenna and rectifier circuit. A 2.45 GHz loop antenna is designed to receive energy and integrated RF rectifier with a good sensitivity in low power application. The optimum RF-to-DC conversion efficiency is 59.4% at 11 dBm input RF power as well as 6.7 V output DC voltages on a 6 KΩ load resistance. Second, the study of the WPS design in near-field application is presented. Here we adopt coils for power transmission by inductive coupling. It contains external circuit design—power amplifier design, and the receiver for implantable circuit design—LC-tank resonator, rectifier and charge circuit. The class-E power amplifier was designed by using IRF540 MOSFET and coils. In the implantable circuit, the coil and capacitor made up a resonator at 1MHz as receiving antenna. At the distance is 10 mm, we can get DC voltage is 46.3 V on load resistor and total efficiency is 31%. In order to apply WPS to human implantable devices, the miniaturized devices are needed. The MEMS (Micro electric Machine System) coils are fabricated on the silicon wafer and glass here as receiving implanted antenna. The line-width, side, and turns of proposed micro-machined coil is 50 um, 10 mm and 10. In the measurement of energy transmission, we could get DC voltage at resistor is 1.8V. Finally, we will discuss the excellences and defects of WPS in far-field and near-field design as well as the feasibility of using MEMS technique to fabricate coil for inductive coupling while combining them with CMOS integrated circuit.

碩士
國立臺北科技大學
電腦與通訊研究所
100
In this thesis, circularly polarized(CP) half&full wave double voltage rectenna for the applications of wireless power transmission has been studied. This study includes: 1. Design of a circularly polarized wide-slot antenna which can reduce the multi-path fading efficiently and solve the depolarization effect of random polarization in free space and complicate environment. 2. Design of the balun and matching network by using the chip components. Through the balun to make unbalanced signals transfer into balanced signals, then the positive or negative signals could totally performed on back-end circuit. It can not only achieve the impedance matching between the receiver antenna and voltage-doubler rectifier, but also suppress the higher order harmonics efficiently. 3. Design of the voltage-doubler rectifying circuit. A RF schottky barrier diode suitable for the current specification and the requirement for design of the voltage-doubler rectifying circuit is selected as a rectifying device of the circuit to increase the output DC voltage and RF-to-DC conversion efficiency. The proposed design of circular polarized slot antenna, balun, matching network and the half/full wave double voltage rectifier which exhibit bandwidth and axial ratio bandwidth are following the specification of IEEE 802.11b (2.4~2.485 GHz). The result of the antenna gain is about 2.2~3.2 dBi. With the present design, a maximum voltage of 8.15 V and a conversion efficiency of 81 % colud be attainable.

碩士
龍華科技大學
電機工程系碩士班
102
In this study, improvement of microwave dielctric properties of Nd(Mg0.5Sn0.5)O3 were investigated. Nd(Mg0.5Sn0.5)O3 ceramics were synthesized and some of the Nd3+ ions were substituted by Sm3+, Yb3+ and Bi3+ ions to improve the Q f. Since Nd0.96Yb0.04(Mg0.5Sn0.5)O3 ceramics had a relatively high temperature coefficient of resonant frequency, an investigation involved tailoring the temperature coefficient of resonant frequency of Nd0.96Yb0.04(Mg0.5Sn0.5)O3 ceramics by combining Ca0.8Sr0.2TiO3. B2O3 was added to reduce the sintering temperature of 0.4Nd0.96Yb0.04(Mg0.5Sn0.5)O3-0.6Ca0.8Sr0.2TiO3 ceramics. The 1.0 wt.% B2O3-droped 0.4Nd0.96Yb0.04(Mg0.5Sn0.5)O3-0.6Ca0.8Sr0.2TiO3 ceramic sintered at 1550 ℃ for 4 hr had a dielectric constant of 38.4, a Q×f of 72,900 GHz, and a temperature coefficient of resonant frequency of 0.2 ppm/℃. The rectenna for wireless power transmission System is fabricated on FR4 substrate. The operating frequency band of the rectenna was designed to comply with IEEE 802.11 b/g 2.4 GHz (2.4~2.4835 GHz). When the distance between receiving and transmitting antenna is about 7 cm, the measurement results show that the receive power and the output efficiency of the rectenna are -10.08 dBm and 26.4%, respectively.

碩士
國立高雄應用科技大學
光電與通訊工程研究所
103
The research of this paper is the design of Circularly Polarized Rectennas for 2.45 GHz energy harvesting system. Interior design proposed energy harvesting system includes the 2.45 GHz Circularly Polarized Antenna and the voltage doubling rectifying circuit. The receiving part uses couple feed to design the circularly polarized antenna. To couple the upper loop structure, and add square structure to make the modal perturbation element separation to achieve circular polarized. Design an array antenna is to gather up the transmitter antenna radiation patterns. Finally the circuit will be designed for the rectifier filter. When RF signals go through the circuit, it can be converted from RF signal to DC signal. The testing result of integration by circuit and antenna shows the voltage reach to 7.44 volts. Furthermore, use the multi-receiving design to make the improvement. It can cover more range, and get the higher volts as well. According to testing result, it can be proved to reach 8.3 volts.