Tunable Platform Tolerant Antenna Design for RFID and IoT Applications Using Characteristic Mode Analysis

Radio frequency identification (RFID) is a key technology to realize IoT (Internet of Things) dreams. RFID technology has been emerging in sensing, identification, tracking, and localization of goods. In order to tag a huge number of things, it is cost-effective to use one RFID antenna for tagging different things. Therefore, in this paper a platform tolerant RFID tag antenna with tunable capability is proposed. The proposed tag antenna is designed and optimized using characteristic mode analysis (CMA). Moreover, this tag antenna consists of a folded patch wrapped around FR 4 substrate and a feeding loop element printed on a paper substrate. The inductive feeding loop is stacked over folded patch and it provides impedance match with RFID chip. Because of separate radiating and feeding element, this tag antenna has a versatility of impedance matching with any RFID chip. Furthermore, this tag is able to cover American RFID band (902-928 MHz) and can be tuned to European RFID band (865-868 MHz) by adding tunable strips. In order to demonstrate platform tolerant operation, the read range of RFID tag is measured by mounting it on different materials. The maximum read range of RFID tag is 4.5 m in free space or on dielectrics and 6.5 m above 200 × 200 mm2 metal plate, respectively

Design and Characterization of a Compact Single Layer Modified S-Shaped Tag Antenna for UHF-RFID Applications

In this paper, we report the design of a new compact single layer modified S-shaped tag antenna for UHF-RFID applications. To achieve a compact size of 51×34 mm2 for this tag antenna, the technique of using S shaped strip is applied, and by further adding a pair of equilateral triangular stubs into this structure, good impedance matching can be obtained at 915 MHz, which is the center frequency of the North-American UHF-RFID band (902 to 928 MHz). Besides exhibiting acceptable 5m read range in free space at 915 MHz, the proposed design shows a read range of about 4.5 when mounted on a metallic object (200 ×30 cm2) separated by spacer foam of thickness 1 cm. Furthermore, the proposed design shows a reasonable read ranges when it is mounted on different dielectrics with low permittivity. The proposed design has a simple configuration, low cost, acceptable read range, and can work on various background materials. &nbsp

Advances in Antennas, Design Methods and Analysis Tools for Passive UHF RFID Tags

Radio-frequency identification (RFID) makes use radio waves to track objects equipped with electronic transponders, commonly known as tags. In passive RFID systems, the tags are remotely powered and they are composed of only two components: an antenna and an application specific integrated circuit (tag IC). At ultra high frequencies (UHF) this technology enables the rapid identification of a large quantity of tags at the distanc-es of several meters, also in the absence of line-of-sight connection with the tag. While the passive UHF RFID is currently used e.g. in supply chain management and access control, in the future the passive tags capable of ultra-low-power data transmission are envisioned to provide platforms for wireless sensor nodes. The maintenance-free and fully integrated on-tag electronics holds the promise to small, cheap, and inconspicuous tags, but achieving this in practice requires completely new design methods and analysis tools for antennas. Unlike conventional antennas, tag antennas need to be directly interfaced with an active load (tag IC) and seamlessly integrated with objects of various sizes and material contents. Here, especially the materials having adverse effect on the operation of conventional antennas present a major challenge, while at the same time the fundamental limitations on the performance of small antennas need to be considered. This work addresses the above-mentioned challenges in the design of antennas for passive tags. Based on the new analysis tools and modern computational electromagnetics, a framework specifically tailored for the development of tag antennas is established. Combined with novel electronics materials and new fabrication methods this is shown to provide compelling means for tag antenna development. In particular, it is shown that tags with antennas produced using printable electronics, which has great potential to enable fabrication antennas directly on various unconventional platforms, can achieve competitive performance against the copper-based references. Furthermore, novel high-permittivity materials can be exploited to develop miniature antennas for metal mountable tags. Finally, three case studies, where antennas for tags in challenging applications are developed using the proposed design framework, are presented. The prototype tags achieve performance exceeding state of the art and exhibit excellent structural properties for the seamless integration with the considered objects

Battery-less near field communications (nfc) sensors for internet of things (iot) applications

L’ implementació de la tecnologia de comunicació de camp proper (NFC) en els telèfons intel·ligents no para de créixer degut a l’ús d’aquesta per fer pagaments, això, junt amb el fet de poder aprofitar l’energia generada pel mòbil no només per la comunicació, sinó també per transmetre energia, el baix cost dels xips NFC, i el fet de que els telèfons tinguin connectivitat amb internet, possibilita i fa molt interesant el disseny d’etiquetes sense bateria incorporant-hi sensors i poder enviar la informació al núvol, dins del creixent escenari de l’internet de les coses (IoT). La present Tesi estudia la viabilitat d’aquests sensors, analitzant la màxima distància entre lector i sensor per proveir la potència necessària, presenta tècniques per augmentar el rang d’operació, i analitza els efectes de certs materials quan aquests estan propers a les antenes. Diversos sensors han estat dissenyats i analitzats i son presentats en aquest treball. Aquests son: Una etiqueta que mesura la humitat de la terra, la temperatura i la humitat relativa de l’aire per controlar les condicions de plantes. Un sensor per detectar la humitat en bolquers, imprès en material flexible que s’adapta a la forma del bolquer. Dues aplicacions, una per estimació de pH i una altre per avaluar el grau de maduració de fruites, basats en un sensor de color. I, per últim, s’estudia la viabilitat de sensors en implants per aplicacions mèdiques, analitzant l’efecte del cos i proposant un sistema per augmentar la profunditat a la que aquests es poden llegir utilitzant un telèfon mòbil. Tots aquests sensors poden ser alimentats i llegits per qualsevol dispositiu que disposin de connexió NFC.La implementación de la tecnología de comunicaciones de campo cercano (NFC) en los teléfonos inteligentes no para de crecer debido al uso de esta para llevar a cabo pagos, esto, junto con el hecho de poder aprovechar la energía generada por el móvil no sólo para la comunicación, sino también para transmitir energía, el bajo coste de los chips NFC, i el hecho que los teléfonos tengan conectividad a internet, posibilita y hace muy interesante el diseño de etiquetas sin batería que incorporen sensores i poder enviar la información a la nube, enmarcado en el creciente escenario del internet de las cosas (IoT). La presente Tesis estudia la viabilidad de estos sensores, analizando la máxima distancia entre lector i sensor para proveer la potencia necesaria, presenta técnicas para aumentar el rango de operación, y analiza los efectos de ciertos materiales cuando estos están cerca de las antenas. Varios sensores han sido diseñados y analizados y son presentados en este trabajo. Estos son: Una etiqueta que mide la humedad de la tierra, la temperatura y la humedad relativa del aire para controlar las condiciones de plantas. Un sensor para detectar la humedad en pañales, impreso en material flexible que se adapta a la forma del pañal. Dos aplicaciones, una para estimación de pH y otra para evaluar el grado de maduración de frutas, basados en un sensor de color. Y, por último, se estudia la viabilidad de sensores en implantes para aplicaciones médicas, analizando el efecto del cuerpo y proponiendo un sistema para aumentar la profundidad a la que estos se pueden leer usando un teléfono móvil. Todos estos sensores pueden ser alimentados y leídos por cualquier dispositivo que disponga de conexión NFC.The implementation of near field communication (NFC) technology into smartphones grows rapidly due the use of this technology as a payment system. This, altogether with the fact that the energy generated by the phone can be used not only to communicate but for power transfer as well, the low-cost of the NFC chips, and the fact that the smartphones have connectivity to internet, makes possible and very interesting the design of battery-less sensing tags which information can be sent to the cloud, within the growing internet of things (IoT) scenario. This Thesis studies the feasibility of these sensors, analysing the maximum distance between reader and sensor to provide the necessary power, presents techniques to increase the range of operation, and analyses the effects of certain materials when they are near to the antennas. Several sensors have been designed and analysed and are presented in this work. These are: a tag that measures the soil moisture, the temperature and the relative humidity of the air to control the conditions of plants. A moisture sensor for diapers, printed on flexible material that adapts to the diaper shape. Two applications, one for pH estimation and another for assessing the degree of fruit ripening, based on a colour sensor. And finally, the feasibility of sensors in implants for medical applications is studied, analysing the effect of the body and proposing a system to increase the depth at which they can be read using a mobile phone. All of these sensors can be powered and read by any NFC enabled device