Nikolai Tesla's revolutionary experiments demonstrated the possible benefits of transmitting power wirelessly as early as 1891. Applications for the military, consumers, emergency personnel, remote sensors, and others use Tesla’s discovery of wireless power. Wireless power transmission (WPT) has the potential to be a common source of consumable energy, but it will only receive serious consideration if the transmit and receive systems are extremely efficient and capable of delivering usable amounts of power. Research has been conducted to improve the efficiency and performance of nearly every aspect of WPT systems, but the relatively new field of metamaterials (MTMs) has yet to play a dominate role in improving system performance. A gradient index (GRIN) MTM lens was designed using Ansoft’s High Frequency Structure Simulator (HFSS) to improve antenna gain and thereby increase WPT system performance. A simple WPT demonstration system using microstrip patch antennas (MPAs) confirmed the benefits of the GRIN MTM lens. The WPT demonstration system, MPAs, and GRIN MTM lens were constructed and experimentally tested near 2.45 GHz. The theoretical and experimental gain improvement of the MPA due to the GRIN MTM lens is 5.91 dB and 7.06 dB, respectively.

Yes / A characteristic loop locus of dc power versus RF output power was observed as the frequency was varied around the optimum point of an operational active antenna. A new technique was introduced into the simulation, plotting the dependence of parameters such as supply current, efficiency or output power on internal impedance as seen by the naked transistor. It is now clear that the loop was formed as a consequence of the interaction of the transistor packaging elements with the patch impedances.

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This master’s thesis describes the design, implementation and testing of an active antenna intended for use with global navigation satellite systems. The active antenna is composed of two major parts, a dual-band circular patch antenna and a dual-band low-noise amplifier. To streamline the design process, a modular solution was adopted. This enabled the functionality of every part in the signal path to be verified before the final active antenna was designed. A practical method to develop dual-band stacked circular patch antennas, along with a systematic way to tune the resonant frequencies and impedance of the antenna, is also presented. Testing of the antenna in realistic scenarios shows that the active antenna performs as expected and predicted by simulations. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>

In satellite applications, a circularly polarized satellite antenna is desirable with a pattern that results in constant received power while the distance between the transmitter and the receiver is changing. The Circular Disk - Annular Ring (CDAR) antenna satisfies these requirements along with other requirements for the satellite antenna. The CDAR antenna is a combination of a Circular Disk and an Annular Ring patch antennas. In this thesis, a circularly polarized CDAR antenna that is fed from a single point is designed at the center frequency of 8.2 GHz. This antenna is investigated and optimized to ease the fabrication process. The design parameters are defined on this report and optimized by using an Electromagnetic Simulation software program. In order to verify the theoretical results, Circular Disk - Annular Ring Antenna is produced as a prototype. Measurements of antenna parameters, electromagnetic field and circuit properties are interpreted to show compliance with theoretical and simulation results. The values of deviation between theoretical and experimental results are also discussed.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / Planar microstrip antennas are desirable in many telemetry applications because they are small in size, light in weight, and conformal to most surfaces. The design and optimization of circularly-polarized omnidirectional microstrip arrays using a new software simulation tool are discussed in this paper. Critical design issues such as the optimization of each array element for circular polarization and the minimization of mutual couplings as well as feed network mismatch are examined. The software tool, which consists of a novel graphical user interface and a full-wave numerical simulator for a flat mounting surface, provides a testbed environment for the user to explore new designs as well as optimizing existing designs. Using this tool, the design of several wraparound arrays with different mounting cylinder radii are presented. Comparisons between measured and simulated data for two S-band 8-element wraparound arrays are also presented.

Modeling of patch antennas and resonators on arbitrary dielectric substrates using surface RWG and volume edge based basis functions and the Method of Moments is implemented. The performance of the solver is studied for different mesh configurations. The results obtained are tested by comparison with experiments and Ansoft HFSS v9 simulator. The latter uses a large number of finite elements (up to 200K) and adaptive mesh refinement, thus providing the reliable data for comparison. The error in the resonant frequency is estimated for canonical resonator structures at different values of the relative dielectric constant ƒÕr, which ranges from 1 to 200. The reported results show a near perfect agreement in the estimation of resonant frequency for all the metal-dielectric resonators. Behavior of the antenna input impedance is tested, close to the first resonant frequency for the patch antenna. The error in the resonant frequency is estimated for different structures at different values of the relative dielectric constant ƒÕr, which ranges from 1 to 10. A larger error is observed in the calculation of the resonant frequency of the patch antenna. Moreover, this error increases with increase in the dielectric constant of the substrate. Further scope for improvement lies in the investigation of this effect.

Antennas enable wireless communication by transmission and reception of electromagnetic (EM) signals, which carry information is space. Signal reception and hence the quality of service depends significantly on the antenna properties, e.g. radiation pattern, operational frequency, and polarization. Legacy antennas, with their fixed properties, fail to adapt to the changing environment and degrade signal quality. Reconfigurable antennas (Ras) capable of changing their properties dynamically increase the capacity and data rate of wireless systems while offering a compact design. However, these advantages come at the cost of increased complexity compared to legacy antennas. Therefore it is important to design Ras with minimal complexity. To that end, this dissertation focuses on the development of a novel approach, three different Ras operation at three different frequency bands have been designed, fabricated and characterized. First RA works at the 5GHz band (4.9-5.1GHz) and obtains on current beam steering and 3-dB beam width variability. An algorithm to choose the optimum mode of operation has also been developed. The design approach introduced in first RA has been exploited to design the second RA, which achieves beam steering and beam width variability for two polarizations and operates a the 28 GHz band (27.5-28.3 GHz). The third RA operates at the 3GHz band and simultaneously reconfigures impedance and radiation patterns.

The aim of this project is to design a microstrip phase array antenna in ADS (Advance Design System) Momentum. The resonant frequency of which is 10 GHz. Two circular patches with a radius of 5.83 mm each are used in designing the array antenna. RT-DURROID 5880 is used as a substrate for this microstrip patch array design. These circular patches are excited using coaxial probe feed and transmission lines of particular lengths and widths. These transmission lines perfectly match the impedance of the circular patches. Various parameters, for example the S-parameters, two dimensional and three dimensional radiation patterns, excitation models, gain, directivity and efficiency of the designed antenna are obtained from ADS Momentum.

At the moment Swedish Transport Administration uses a monitor system that candetect urgent errors as warm ball-bearings and flat wheels etc. with stationarydetectors. To avoid these errors Swedish Transport Administration, UPWIS AB andUppsala University work with a system that will continuously monitoring the train todetect the errors as fast as possible. This will save money in the future for SwedishTransport Administration and all other partners that use the rails.Swedish Transport Administration has already RFID readers beside the rail to detecttrains position. The new monitoring system will use these readers and send data fromthe monitoring system via these readers to a database.The aim of this thesis work is to design and build a RFID antenna to send data fromthe monitoring system to the RFID readers. The antenna should be a circularpolarized and it needs to manage the harsh environment on the train.This thesis work started with a theoretical study which investigated four commonantenna types (dipole, loop, PIFA and patch/microstrip) to evaluate which antennatype that is the best solution for this application. It was decided to design a patchantenna from the theoretical study since it fulfils all the requirements for the antenna.Simulations and tests shows that the antenna is circular polarized and have amaximum reading distance of 5 m for 868 MHz. For 2.45 GHz it is linear polarizedand has a reading distance of at least 10 m. With other hardware settings the antennawill have longer reading distance at 2.45 GHz.When all parts of the test bed was finished the test bed was mounted on themeasurement wagon. The final test shows that the antenna fulfils the task. Theantenna transmitted the data from the sensor boxes to the RFID readers.The report suggests future work to minimize the reading distance and size for theantenna. These are: transfer sensor data to RFID tag by “multi hop”, hardwareimprovement for instance antenna diversity and using another substrate (higherdielectric constant).