This report documents the design, construction, and implementation of a differential-offset spread spectrum RFID system, to avoid the problem of anti-collision interference from multiple RFID tags. Currently in industry, this problem is handled by establishing a two way communication link between the tags and the interrogator. The proposed system eliminates the need for the excessive hardware use to create this link, and therefore drastically reduces the cost of each tag. Not only is this system cheaper to implement but it is faster, requires less power, and by the nature of the design contains an inherent encryption scheme for the data being transmitted. Specialized RFID tags were designed and fabricated in order to produce a pseudo random code unique to each tag. The design presented in this document allowed simultaneous interrogation of up to 255 tags within one sensing environment. Once queried, the tags then modulate the incoming signal from the interrogator with their own sequence, and reflect the signal back to the interrogator. What the interrogator then receives is a combination of backscatter from all of the tags within the sensing environment. Specialized software written in Matlab and LabView uses these unique sequences to isolate the data from a desired tag away from the sea of information being transmitted from every tag. Using this system, numerous applications for experiments and measurements can be devised. One such application this thesis focuses on is the use of this system to simultaneously measure signal strengths from multiple diversity antennas in order to optimize their position and orientation. Currently, the majority of antenna diversity measurements are taken by measuring the signal strength of a given configuration one antenna at a time. By using the anti-collision RFID system proposed above, the signal strength produced by both antennas can be measured and recorded simultaneously to provide a true representation of their combined performance. This measurement can be used to find the optimal configuration for multiple antennas. This thesis will fully explore the theories and procedures behind creating this system, and will provide the results and analysis of its performance.

With higher frequencies now being used in RFID systems, antennas are becoming much smaller resulting in more space on tags that can be used for innovative array designs to harvest more wireless energy. This master's thesis outlines and details a new methodology for designing and simulating the staggered pattern charge collector, a technique to improve harvesting wireless energy. Staggered pattern charge collectors enable RFID tag's to produce a higher DC voltage from a charge pump circuit by creatively using multiple arrays to increase the antenna power conversion gain without limiting the half power beamwidth. This thesis discusses the basics of patch antennas and charge pumps as well as an optimization technique for the staggered pattern array by maximizing integrated power conversion gain (IPCG). An example of a staggered pattern charge collector is fully specified from design through simulation, in preparation for fabrication. This methodology allows for the staggered pattern charge collectors to be designed, simulated, and fabricated quickly and effectively.

Navigation through large and unfamiliar facilities with labyrinths of corridors and rooms is difficult and often results in a person being lost. Additionally, locating a specific utility within a facility is often a tough task. The hypothesis tested in this research is that integrating real-time automated sensing technology and a Building Information Model will provide real time visualization that can assist in localization and navigation of a facility. The scope of this research is facility maintenance management during the Operation and Maintenance (O&M) phase of a facility. The thesis demonstrates how the integration of passive Radio Frequency Identification (RFID) tracking technology and Building Information Modeling (BIM) can assist in facilities maintenance management. The objectives of this research included 1) developing a framework that utilizes the integration of commercially-available RFID and a BIM model; 2) evaluating the framework for real-time resource location tracking within an indoor environment; and 3) developing an algorithm for real-time localization and visualization in a BIM model. A prototype application has been developed that simultaneously connects the RFID readers, a database, and a BIM model. The goal of this system is to have a real-time localization accuracy of 3 meters at 95% confidence. Testing was conducted in laboratory conditions, and the results show that the system error was within the 3 meters goal.

Backscatter radio - the broad class of systems that communicate using scattered electromagnetic waves - is the driving technology behind many compelling applications such as radio frequency identification (RFID) tags and passive sensors. These systems can be used in many ways including article tracking, position location, passive temperature sensors, passive data storage, and in many other systems which require information exchange between an interrogator and a small, low-cost transponder with little-to-no transponder power consumption. Although backscatter radio is maturing, such systems have limited communication range and reliability caused, in part, by multipath fading. The research presented in this dissertation investigates how multipath fading can be reduced using multiple antennas at the interrogator transmitter, interrogator receiver, and on the transponder, or RF tag. First, two link budgets for backscatter radio are presented and fading effects demonstrated through a realistic, 915 MHz, RFID-portal example. Each term in the link budget is explained and used to illuminate the propagation and high-frequency effects that influence RF tag operation. Second, analytic envelope distributions for the M x L x N, dyadic backscatter channel - the general channel in which a backscatter system with M transmitter, L RF tag, and N receiver antennas operates - are derived. The distributions show that multipath fading can be reduced using multiple-antenna RF tags and by using separate transmitter and receiver antenna arrays at the interrogator. These results are verified by fading measurements of the M x L x N, dyadic backscatter channel at 5.8 GHz - the center of the 5725-5850 MHz unlicensed industrial, scientific, and medical (ISM) frequency band that offers reduced antenna size, increased antenna gain, and, in some cases, reduced object attachment losses compared to the commonly used 902-928 MHz ISM band. Measurements were taken with a custom backscatter testbed and details of its design are provided. In the end, this dissertation presents both theory and measurements that demonstrate multipath fading reductions for backscatter-radio systems that use multiple antennas.

La technologie RFID (Radio Frequency Identification) prend une place de plus en plus importante dans la société d'aujourd'hui notamment dans des domaines aussi variés que la santé, la sécurité, la logistique... Le développement de cette technologie met en évidence de nouvelles contraintes comme la réduction des zones de lecture et la géo-localisation pour le stockage et le suivi de marchandises. Dans ce contexte, la thèse s'est focalisée sur le développement d'antennes pour lecteur RFID dans le cadre du projet SPINNAKER piloté par TAGSYS RFID et soutenu par OSEO. L'objectif de cette étude est de concevoir des antennes compactes et directives à polarisation circulaire en bande UHF et SHF. L'antenne hélice présente toutes ces caractéristiques à l'exception de la hauteur, très importante dès que l'on souhaite obtenir des performances élevées surtout en gain. Dans ce manuscrit, trois solutions sont proposées pour réduire la hauteur de l'antenne hélice tout en répondant aux cahiers des charges. La première solution consiste à utiliser un réflecteur de forme cylindrique ou conique qui permet de réduire la hauteur d'une antenne hélice classique d'un facteur quatre pour atteindre 0,9λ. La réduction de la hauteur se traduit par une augmentation de la surface autour de l'antenne avec une dimension latérale de 2,3λ. La seconde solution consiste à utiliser l'antenne hélice avec une cavité Fabry-pérot. La hauteur du système antennaire obtenue est de 0,5λ avec un diamètre de 2λ. La dernière solution développée dans la thèse introduit une surface CMA à la solution précédente qui permet de réduire la hauteur à 0,25λ. Toutes les solutions proposées ont été validées expérimentalement. / Over the past 20 years, the RFID (Radio Frequency Identification) technology is having a huge expansion. Nowadays, it is frequently used in different areas as the health, the security and the logistic. A lot of researches are ongoing on this topic, especially in order to reduce the reading zone of the readers and to locate the tags. This thesis focuses on the development of new antennas for Readers RFID devices and is part of the SPINNAKER project supported by OSEO. The antennas requirements are circular polarization, high directivity and gain with low profile. The helix antennas meet all these requirements except the axial length. In this manuscript, we propose three solutions to reduce the helix antenna axial length. The first one uses a cylindrical or conical optimal reflector to reduce the length by four. This reduction affects directly the surface witch increases up to 2.3λ. The second solution uses the helix antenna as a circular polarization feed for a Fabry-Perot (FP) cavity. The final antenna presents a cavity height of 0.5λ and a 2λ diameter. The last solution conserves the FP cavity in which we include an Artificial Magnetic Conductor (AMC) to reduce the cavity height to 0.25λ. All these solutions are validated by measurements.

Radio Frequency Identification (RFID) technology is a ethod of identifying unique items using radio waves that communicate between RFID tags and readers without line-of-sight readability. RFID technology provides great potential in many industries and a wide spectrum of possible uses. Areas of application include person identification, logistics, pharmaceutical, access control, security guard monitoring and asset management. One of the areas where RFID is being used and where it promises excellent results is the retail industry. While RFID systems have the potential to revolutionise the way products and goods are tracked and traced in the retail supply chain, barriers to its widespread adoption exist: for example; technical constraints, return on investment constraints, a lack of awareness and education and as well as privacy and security issues. The research aims to identify the barriers to the adoption of RFID and to investigate the perceptions of RFID held by members of the retail sector in South Africa (SA). Current research and available literature are used to identify RFID adoption barriers and a conceptual framework on this subject is proposed, which is then verified by SA retailers’ perceptions, established by means of a survey. Initial barriers to widespread adoption include a shortage in skills, a lack of standards, high costs associated with RFID devices, the difficulty of integrating with current legacy systems, and a lack of familiarity with the system. Finally, an enhanced framework is proposed, describing RFID adoption barriers within the South African retail sector. In summary, the framework is an outline of the barriers impacting RFID adoption in the SA retail sector that need to be considered and addressed. The framework identifies six categories of RFID adoption barriers, with each category containing two or more barriers relating to that particular category. These categories are Technological, Cost and return on investment, Privacy and security, Implementation, Organisational factors and People.

Surface acoustic wave (SAW) sensors offer a wireless, passive sensor solution for use in numerous environments where wired sensing can be expensive and infeasible. Single carrier frequency SAW sensor embodiments such as delay lines, and resonators have been used in single sensor environments where sensor identification is not a necessity. The orthogonal frequency coded (OFC) SAW sensor tag embodiment developed at UCF uses a spread spectrum approach that allows interrogation in a multi-sensor environment and provides simultaneous sensing and sensor identi- fication. The SAW device is encoded via proper design of multiple Bragg reflectors at differing frequencies. To enable accurate device design, a model to predict reflectivity over a wide range of electrode metallization ratios and metal thicknesses has been developed and implemented in a coupling of modes (COM) model. The high coupling coefficient, reflectivity and temperature coefficient of delay (TCD) of YZ LiNbO3 makes it an ideal substrate material for a temperature sensor, and the reflectivity model has been developed and verified for this substrate. A new concept of pseudo-orthogonal frequency coded (POFC) SAW sensor tags has been investigated, and with proper design, the POFC SAW reduces device insertion loss and fractional bandwidth compared to OFC. OFC and POFC sensor devices have been fabricated at 250 MHz and 915 MHz using fundamental operation, and 500 MHz and 1.6 GHz using second harmonic operation. Measured device results are shown and compared with the COM simulations using the iii enhanced reflectivity model. Additionally, the first OFC devices at 1.05 GHz were fabricated on 128o YX LiNbO3 to explore feasibility of the material for future use in OFC sensor applications. Devices at 915 MHz have been fabricated on YZ LiNbO3 and integrated with an antenna, and have then been used in a transceiver system built by Mnemonics, Inc. to wirelessly sense temperature. The first experimental wireless POFC SAW sensor device results and predictions will be presented.

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Thesis ( M. Tech. (Business Administration )) - Central University of Technology, Free State, 2014 / Fast and secure public service delivery is not only a necessity, but a compulsory endeavour. However, it is close to impossible to achieve such objectives without the use of Information Technology (IT). It is correspondingly important to find proper sustainability frameworks of technology. Organisations do not only need technology for efficient public service; the constant upgrading of systems and cautious migration to the newest IT developments is also equally indispensable in today’s dynamic technological world. Conversely, countries in Africa are always lagging behind in technological progresses. Such deficiencies have been identified in the passport processing of Lesotho and South Africa, where to unequal extents, problems related to systems of passport production have contributed to delays and have become fertile grounds for corrupt practices. The study seeks to identify the main impediments in the adoption of Management Information Systems (MIS) for passport processing. Furthermore, the study explores the impact MIS might have in attempting to combat long queues and to avoid long waiting periods – from application to issuance of passports to citizens. The reasonable time frame between passport application and issuance, and specific passport management systems, have been extensively discussed along with various strategies that have been adopted by some of the world’s first movers in modern passport management technologies. In all cases and stages of this research, Lesotho and South Africa are compared. The research approach of the study was descriptive and explorative in nature. As a quantitative design, a structured questionnaire was used to solicit responses in Lesotho and South Africa. It was established that both Lesotho and South Africa have somewhat similar problems – although, to a greater extent, Lesotho needs much more urgent attention. Although the processes of South Africa need to be improved, the Republic releases a passport much faster and more efficiently than Lesotho. Economic issues are also revealed by the study as unavoidable factors that always affect technological developments in Africa. The study reveals that the latest MIS for passport processing has facilitated modern, automated border-control systems and resultant e-passports that incorporate more biometric information of citizens to passports – thanks to modern RFID technologies. One can anticipate that this study will provide simple, affordable and secure IT solutions for passport processing. Key words: Information Technology (IT); Management Information Systems (MIS); E-Government; E-Passport; Biometrics; and RFID.

Thesis presented in partial fulfilment of the requirements for the Master's Degree of Technology: Information Technology, Durban University of Technology, 2008. / Radio Frequency Identification (RFID) allows for the wireless transfer of data between a small electronic transmitting tag and a reader without the necessity of line-of-sight. A feature of RFID, is that this read operation may occur over long distances and that multiple reads may occur. The aim of this study is to analyse the nature and extent of RFID adoption in the KwaZulu-Natal Province of South Africa. The study fits within the theory of innovation diffusion and is concerned with issues around technology diffusion, adoption rates, and its associated critical success factors. The estimation of RFID diffusion rate in the study is based on a telephonic survey of 140 companies. The respondents were chosen from a marketing database that had extensive information on South African companies. Size was determined to be the selection criterion as the literature indicates that size is the most compelling concomitant to innovativeness. In this study, size was deemed to be companies that had more than 50 PC’s in one geographic unit, of the company, in KwaZulu-Natal. The key research result locates the RFID diffusion rate in KwaZulu-Natal to be around 19% which corresponds to points beyond the “chasm” as defined by innovation diffusion theory. The second phase of the study comprised the administration of a questionnaire to two groups of IT professionals with the aim of comparing perceptions and other characteristics between the two groups. The 140 respondents were asked to submit as many professional staff as they could for an in-depth interview. The result was that 21 companies submitted 30 candidates. This yielded the two groups: the Adopter sample with 14 respondents, and the non-adopter sample with 16 respondents. The analysis of results shows the two groups have similar views on many strategic factors such as privacy, security, cost and standards etc. Adopters perceive that the following factors impacts RFID adopting decisions more (than non-adopters): Turnover, Having labour cost savings, RFID ubiquity, It will take as long for my company to adopt RFID as it did for barcode, RFID cost awareness. On the other hand non-adopters felt that the following factor impacts non-adoption of RFID Technology unproven or immature, Human skills non-availability, Implementation costs, Corporate resistance, and, Support Concerns.