This paper presents the design, realization, and experimental validation of a battery-assisted radio frequency identification (RFID) tag with sensing and computing capabilities conceived to explore heterogeneous RFID-based sensor network applications. The tag (hereafter called mote) features an ultra-low-power ferroelectric random-access-memory microcontroller, a LED, temperature and light sensors, three-axis accelerometer, non-volatile storage, and a new-generation I2C-RFID chip for communication with standard UHF EPCglobal Class-1 Generation-2 readers. A preliminary RFID mote prototype, fabricated on a printed circuit board using low-cost discrete components and equipped with a small 225-mAh coin battery, provides an estimated lifetime of 3 years when sensing and computing tasks are performed every 30 s. In addition, the reliable RFID communication range up to 22 m achieved in an indoor scenario represents, to the best of our knowledge, the longest distance ever reported for similar sensor-enhanced RFID tags. © 2013 IEEE.

The rigorous characterization of ultrahigh-frequency passive radio-frequency identification (RFID) tags is a challenging but mandatory task. Indeed, tags are the most critical devices in RFID systems: their performance should be adequately good, although stringent requirements in terms of compactness, used materials, and costs must be satisfied. Factors such as the goodness of the conjugate impedance matching between the chip and the antenna, the chip sensitivity, and the quality of the backscattered signal affect tag performance. Tag sensitivity and differential radar cross section (RCS) are the most significant metrics for tag characterization: they define the forward (from the reader to the tag) and the backward (from the tag to the reader) link reliability, respectively. Nevertheless, measurement of such metrics cannot be approached with conventional methods based on vector network analyzers or conventional RFID readers. Vice versa, commercially available instrumentation and solutions are very expensive and not totally flexible. In this paper, a novel approach for performance characterization of RFID tags is explored. To this end, we developed a very cheap (below $1000) and flexible tool based on software-defined radio, which enables measurement of tag sensitivity and differential RCS. An exhaustive experimental campaign has been carried out on ten commercial and four built-in laboratory RFID tags. Achieved results demonstrate the flexibility, accuracy, and appropriateness of the proposed approach.

This paper presents a proposal for a context-aware framework. The framework is organised according to a general purpose architecture, centred around an ontological context representation. The ontology provides the vocabulary upon which software agents interoperate and perform rule-based reasoning, in order to determine the system response to context changes. Context data are provided by both static and dynamic sources, the core of which is a novel low-cost device enabling the integration of sensor networks with RFID systems. This paper describes system components and their coordinated operations by providing a simple example of concrete application in a home-care scenario.

In this paper, a RF-DC voltage multiplier operating at 13.56MHz (in the European HF RFID standard band) with -19dBm sensitivity is presented. It is made by a Dickson's RF-DC rectifier and an additional Pelliconi's charge pump driven by a fully integrated 50kHz ring oscillator. Mathematical model is developed and verified through measurements. Silicon prototypes have been realized in 350nm CMOS technology. Measurements show an output voltage ranging from 0.5V up to 3.11V. © 2015 IEEE.

This paper describes how novel knowledge modeling and management techniques borrowed from the Semantic Web were exploited to publish data coming from Electromagnetic (EM) pollution monitoring to the Linked Data Cloud. The paper shows how, starting from requirements coming from the EM use case, the procedure of data publishing was carried out, with the support of public tools, shared standards and established methodologies. A synthetic comparison between available tools is provided, a knowledge model integrating proprietary and public ontologies and vocabularies described, and a practical use case narrated. In this way, starting from a concrete use case, a panoramic on Linked Data capabilities and on state-of-art procedures, tools and standards is provided.

In this paper, the design, realization, and experimental validation of a battery-assisted radio frequency identification (RFID) tag featuring sensing and computation capabilities are presented. The sensor-augmented RFID tag comprises an ultra-low-power microcon-troller, temperature sensors, 3-axis accelerometer, non-volatile storage, and a new-generation I2C-RFID chip for communication with standard UHF EPCglobal Class-1 Generation-2 readers. A preliminary printed-circuit-board prototype, connected to a 3-V/225-mAh lithium battery, provides a lifetime up to approximately 3 years when sensing and RFID-based communication tasks are performed every 10 seconds. Moreover, the device exhibits indoor transmission ranges up to 22 m, 6 m, and 5 m when attached to foam, concrete, and wood respectively. The encouraging results achieved for an emulated application scenario demonstrate the suitability of the device to be adopted in contexts where temperature and acceleration sensing are required.

In this paper, a network approach for the analysis of a wireless resonant energy link consisting of N inductively coupled LC resonators is proposed. By using an artificial transmission line approach, the wireless link is modeled as a transmission line described by effective parameters. It is shown that the analyzed system exhibits a passband filter behavior. More specifically, the reported results demonstrate that in the wireless link passband the effective parameters assume negative values resulting in a negative phase delay. Useful design formulas are derived and validated by comparisons with the experimental data.

The huge progress made in Radio Frequency Identification (RFID) technology has led to the development of cost-effective and high performing passive tags, thus paving the way to a widespread diffusion of such a technology. Working distances of almost ten meters and cost of the tag of a few euro cents, in fact, make effectively practicable the RFID-based solution of many auto-identification applications, that were prohibitive before. At present, the new challenge is the realization of a new kind of passive RFID tags which, while preserving low cost, ease of use and performance of traditional RFID, is able to transmit, along with the ID code, the values measured by sensors. In this paper, we propose a new version of our already published RFID Sensor-Tag. The renovated version takes advantage from an overall design of the circuit, including antennas, microwave switches and logical units. In such a way, thanks to consolidate techniques for the circuit miniaturization as well as optimization processes for the minimization of the coupling effects, the proposed device is rather compact and very well-performing. © 2011 EurAAP.

This paper presents a novel biotelemetry system based on a fully-passive architecture; High Electron Mobility Transistors are used as sensing elements. The main advantages and drawbacks related to the approach here proposed are deeply analyzed and some possible solutions identified. Furthermore, some preliminary experimental results are given and discussed.

This paper presents a novel electrical model of multi-walled carbon-nanotube based gas sensors completely patterned using low-cost inkjet printing. The obtained results (validated through measurements from 50 MHz to 3 GHz) demonstrate that the nanostructure-based sensing mechanisms yields a quite evident shift of circuit resistive elements. A narrowband investigation of the resistive variation depending on gas concentration has been performed as well. The input impedance has been found to be significantly lower than that reported for metal oxide sensors, thus facilitating the integration in electronic circuitry. The suggested equivalent model can be exploited in the implementation of large-scale nanotechnology-enabled inkjet-printed modules.

In this paper, a UHF-RFID power management circuit is presented. It is able to power body sensor networks nodes, starting from -25dBm UHF-RFID input signal power. It is based on an initial Dickson's RF-DC rectifier circuit, followed by an ultra-low-voltage integrated boost converter, realized in 180nm CMOS technology, that is used to further step-up of the rectified DC-voltage and to guarantee the RF-to-load isolation. Measurements demonstrate the ability of the power management circuit to provide 400mV output voltage when a -25dBm continuous wave at 866.5MHz (European UHF RFID frequency) is applied at the input. © 2015 IEEE.

This paper presents a wireless energy link for wearable applications. The proposed link exploits a magnetic coupling between two resonators fabricated by using a conductive non-woven fabric for the conductive parts and leather as substrate, thus resulting in a prototype that can be easily embedded in wearable accessories such as fashion bags. Experimental data referring to a prototype working in the ISM band (433.05 - 434.79 MHz) demonstrate a power transfer efficiency of about 69 %.

A wireless charger for low capacity thin-film batteries is presented.Theproposed device consists of a nonradiative wireless resonant energy link and a power management unit. Experimental data referring to a prototype operating in the ISM band centered at 434MHz are presented and discussed. In more detail, in order to facilitate the integration into wearable accessories (such as handbags or suitcases), the prototype of the wireless energy link was implemented by exploiting a magnetic coupling between two planar resonators fabricated by using a conductive fabric on a layer of leather. From experimental data, it is demonstrated that, at 434MHz, the RF-to-RF power transfer efficiency of the link is approximately 69.3%. As for the performance of the system as a whole, when an RF power of 7.5 dBmis provided at the input port, a total efficiency of about 29.7% is obtained. Finally, experiments performed for calculating the charging time for a low capacity thin-film battery demonstrated that, for RF input power higher than 6 dBm, the time necessary for recharging the battery is lower than 50 minutes.

This paper presents a new wireless power link fabricated by using a conductive non-woven fabric on a leather substrate, thus resulting in a prototype that can be easily embedded in wearable accessories such as fashion bags. More in detail, in the fabricated prototype (which was designed to work in the ISM band 433.05 - 434.79 MHz), the power transfer was implemented by exploiting a magnetic coupling between two planar resonators. The results related to the characterization of the fabricated wireless power link are presented and discussed. In particular, from experimental data, a power transfer efficiency of about 69 % is demonstrated.

This work presents the progress in the design of smart, multi-function, RFID-enabled devices at the Electromagnetic Lab Lecce. Specifically, the preliminary prototypes of SPARTACUS and RAMSES, which are the two UHF RFID tags with augmented capabilities introduced in our earlier works, have been significantly improved in terms of compactness, sensing, computation, and antenna design. The achieved operating ranges and sensing performance are the main strengths making the two devices definitely suitable for a wide array of applications.

Wireless Sensor Networks (WSNs) are receiving an ever increasing attention because they are one of the most important technologies enabling the Internet of Things vision. Since nodes of these networks are battery-powered, energy efficiency represents one of the main design objectives. This goal can be primarily achieved through an optimization of the communication phase, which is the most power consuming operation for a WSN node. However, the limited computational and storage resources of physical devices make the design of complex communication protocols particularly hard, suggesting, on the contrary, to integrate more simple communication protocols with hardware solutions aimed at energy saving. In this work, a new MAC protocol, compatible with the IEEE 802.15.4 standard, and a reconfigurable beam-steering antenna are presented and validated. They significantly reduce the nodes’ power consumption by exploiting scheduling techniques and directional communications. Specifically, both during transmission and receiving phases, the node activates exclusively the antenna sector needed to communicate with the intended neighbour. The designed antenna and the proposed protocol have been thoroughly evaluated by means of simulations and test-beds, which have highlighted their good performance. In particular, the MAC protocol has been implemented on the Contiki Operating System and it was compared with the IEEE 802.15.4 standard solution.

The adoption of solutions based on Radio Frequency IDentification (RFID) technology in a large number of contexts is a matter of fact. In many situations, such as the tracking of small living animals, the straightforward use of commercial systems does not guarantee adequate performance. Consequently, both the RFID hardware and the control software platform should be tailored for the particular application. In this work, the specific requirements of Near Field (NF) Ultra High Frequency (UHF) RFID reader antennas suitable for small animal localization and tracking are individuated and a control system based on NI LabVIEW has been designed. Afterwards, both hardware and software solutions have been implemented and validated by using a living laboratory approach. Finally, the set-up of a first working prototype involving six built-in-lab NF antennas has been completed and tested. The achieved results are impressive and demonstrate the appropriateness of the proposed approach.

The introduction of Internet of Things enabling technologies into the sport and recreational activities domain provide an interesting research challenge. Their adoption could significantly improve the sport experience and also the safety level of team sports. Despite this, only few attempts have been done to demonstrate the benefits provided by use of IoT technologies in sport environments. To fill this gap, this paper propose an IoT- aware Sport System based on the jointly use of different innovative technologies and standards. By exploiting the potentialities offered by an ultra-low-power Hybrid Sensing Network (HSN), composed of 6LoWPAN nodes integrating UHF RFID functionalities, the system is able to collect, in real time, both environmental parameters and players’ physiological data. Sensed data are then delivered to a Cloud platform where a monitoring application makes them easily accessible via REST Web Services. A simple proof of concept has demonstrated the appropriateness of the proposed solution.

Over the last few years, the convincing forward steps in the development of Internet-of-Things (IoT) enabling solutions are spurring the advent of novel and fascinating applications. Among others, mainly Radio Frequency Identification (RFID), Wireless Sensor Network (WSN), and smart mobile technologies are leading this evolutionary trend. In the wake of this tendency, this paper proposes a novel, IoTaware, smart architecture for automatic monitoring and tracking of patients, personnel, and biomedical devices within hospitals and nursing institutes. Staying true to the IoT vision, we propose a Smart Hospital System (SHS) which relies on different, yet complementary, technologies, specifically RFID, WSN, and smart mobile, interoperating with each other through a CoAP/6LoWPAN/REST network infrastructure. The SHS is able to collect, in real time, both environmental conditions and patients’ physiological parameters via an ultra-low-power Hybrid Sensing Network (HSN) composed of 6LoWPAN nodes integrating UHF RFID functionalities. Sensed data are delivered to a control center where an advanced monitoring application makes them easily accessible by both local and remote users via a REST web service. The simple proof of concept implemented to validate the proposed SHS has highlighted a number of key capabilities and aspects of novelty which represent a significant step forward compared to the actual state of art.

Animal tracking and animal behavior analysis have a crucial impact in biomedical disciplines to study newpathologies and effects of newdrugs. There are several solutions, based on different technologies such as GPS, radar, and vision, designed to obtain animals tracking systems, but they are effective mainly in presence of large size animals and outdoor environment. Unfortunately, they show poor performance when groups of small laboratory animals have to be monitored in indoor environments. In such a context, the adoption of passive Near Field (NF) Ultra High Frequency (UHF) Radio Frequency Identification (RFID) technology seems to be a winning approach, even though the straightforward use of commercial solutions does not guarantee satisfactory performance. Specifically, customized hardware and software solutions are then required. The main goal of this work is to present the development and then to validate a reliable and effective system for the automatic tracking of laboratory mice, based on suited NF UHF RFID hardware capturing system combined with an ad hoc software system able to guarantee hardware control, data processing, and reporting. In particular, the validation phase has been carried out by selecting the most appropriate RFID tags and by surgically implanting them into laboratory mice. Experimental results have demonstrated the efficiency of the proposed solution, which is able to gather data on the animal movements, allowing their nsubsequent processing for a satisfactory behavioral analysis.

An RF-DC converter enhanced by a DC-DC voltage booster in silicon-on-insulator technology for UHF radio frequency identification (RFID) energy harvesting is presented in this letter. When the received RF power level is -14 dBm or higher, the system, fabricated on an FR4 substrate using off-the-shelf low-cost discrete components and connected to a flexible dipole antenna, is able to produce 2.4 V DC voltage to power general-purpose electronic devices. As a simple proof of concept, a device comprising microcontroller, temperature sensor, and EEPROM is considered in this work. The experimental results demonstrate the capability of the system to autonomously perform temperature data logging up to a distance of 5 m from a conventional UHF RFID reader used as an RF energy source. © 2001-2012 IEEE.

The paper presents a novel planar dipole for Ultra-High-Frequency (UHF) Radio Frequency Identification (RFID) systems is here presented. Referring to a realization based on the use of a chip produced by Texas Instruments, the proposed design approach has been numerically and experimentally investigated. Reported results demonstrate that the proposed antenna exhibits good radiation properties and matching (|S11|<-10 dB) over the entire UHF RFID bandwidth (860-960 MHz).

This paper presents a broadband planar antenna; experimental results demonstrate a relative bandwidth of 122%. As an example of application, the antenna is used in the design of a rectenna for RF energy scavenging, with promising performance.

Current Radio-Frequency Identification (RFID) technology involves two types of physical devices: tags and reader. The reader combines in a single physical device transmission (to the tags) and reception (from the tags) functions. In this paper we discuss an alternative approach, where receive functions are performed by a separate device called "RFID listener". This allows distributed tag-sensing schemes where one transmitter coexists with multiple listeners. We discuss pros and cons of both approaches and present our implementation of a passive RFID listener on GNU Radio. Our implementation is a basis for experimenting with future distributed listener-based systems, but it can be also used as a cheap and flexible protocol analyzer for currently available commercial RFID readers.

In this paper, a wearable resonator suitable to be used for both power and data transmission is presented. The basic element is a complementary split ring resonator that has been optimized to operate both as a dipole-like antenna at 2.45 GHz and as the receiver of a resonant energy link operating at 915 MHz when coupled with an identical external resonator connected to a power source. Experimental data referring to a prototype fabricated by using a conductive adhesive fabric on a leather substrate are reported and discussed. With regard to the wireless resonant energy link (WREL), it is demonstrated that at 915 MHz, the RF-to-RF power transfer efficiency of the link is approximately 78.1%. As for the performance obtained when the resonator is used as an antenna, a gain of approximately −0.43 dB was obtained. Additionally, the performance of the proposed link when connected to a Power Management Unit (PMU) that converts the radio frequency (RF) energy received by the wearable resonator into DC energy that can be directly used for recharging a thin-film battery was also investigated. Experimental tests were performed in order to evaluate both the total efficiency of the wireless charger (i.e., the WREL link connected to the PMU) and the time necessary to recharge a THINERGY MEC201 battery. The obtained results demonstrate the feasibility of using the proposed WREL for implementing a battery charger; in particular, by providing an input power higher than 8 dBm, the time necessary to recharge the considered thin-film battery is shorter than 38 min.

Energy saving is one of the most important issues in wireless sensor network (WSN) context. The bottleneck of WSN nodes is the limited battery life and, in most cases, it is inconvenient or even impossible to replace the energetic module. Since the communication task is highly most power consuming, it is quite important to achieve an energy efficient communication in order to increase the lifetime of the devices through an intelligent use of the power transmission. In this paper, the integration of WSN nodes with switched-beam antennas is becoming more and more appealing due to the possibility to extend sensor node lifetime by optimizing the transmitted power. In this paper, a switched-beam antenna for WSNs nodes in the ISM band is proposed. The radiating structure consists of four identical antennas, composed of an array of two L-shaped quarter-wavelength slot antenna elements arranged in a compact and symmetrical planar structure. Thanks to a properly designed switching circuit which controls the feeding of the antenna elements, one among eight possible different radiation patterns in the azimuth plane (horizontal plane) can be selected on the basis of specific needs. Simulations and experimental results, referred to a prototype realized on an FR-4 substrate, demonstrate the appropriateness of the proposed switched-beam antenna system as hardware element enabling new power saving strategies in WSN contexts. © 2012 IEEE.

The astonishing boom of radio-frequency identification (RFID) technology is stimulating plenty of new RFID-based industrial applications. Consequently, in the very near future, an almost unlimited number of RFID tags could be embedded into manufactured goods of various shapes, assets, and machineries to enable their communication abilities. As a result, prototyping techniques of RFID tags on flexible substrates are becoming more crucial. In this article, four different techniques suitable for prototyping flexible tags are briefly explained and tested from many points of view: Ease of use, processing time, cost, tag sensitivity, radiation pattern, impedance, and robustness of the realized prototype. Characterization methods and experimental setups are presented, and two tag layouts, one commercial and one appositely designed, are used to compare the different techniques. © 2017 IEEE.

This paper provides a rigorous theoretical formulation to obtain an inductive resonant wireless power transfer (WPT) link with load-independent output voltage or current. This is a crucial working condition for wireless battery recharging, where there is no deterministic knowledge of load variation with respect to the battery charging level. The ideal lossless and the realistic lossy configurations are considered for both voltage- and current-excited WPT links. The link transfer matrix (ABCD matrix) is used to determine the operating frequencies where a load-independent output voltage or current can be obtained. It is shown that in the lossy cases that an almost load-independent behavior can be achieved, provided that the load resistance lies in a suitable range and analytical conditions on the load resistance value have been derived. The analytical relationships obtained by this theory are validated by means of both circuit simulation and experimental data at 13.56 MHz.

The performance evaluation of radio-frequency identification (RFID) tags is an important task both for tag designers and final users. Approaches based on the use of Vector Network Analyzers rather than conventional RFID readers only provide partial characterizations. On the contrary, commercial solutions, although they are able to guarantee an accurate and complete performance evaluation, require significant investment. This work presents a cost-effective but accurate characterization system for the performance evaluation of UHF RFID tags. It is based on a programmable and GPIO-provided UHF RFID reader connected to a circularly polarized antenna and driving a stepper motor to modify the tag orientation. The system is able to determine the minimum power emitted by the interrogating reader capable to energize the tag under test, and to derive from it the most significant metrics characterizing the tags: maximum and angular tag sensitivity, maximum and angular working range, and tag antenna radiation pattern. The proposed UHF RFID tag characterization system is validated through comparison with a commercial solution in terms of tag sensitivity and radiation pattern which demonstrate the correctness of the proposed approach. © 2015 IEEE.

Passive Radio Frequency Identification (RFID) is an emerging technology allowing the automatic identification of passive devices, called tags, when interrogated by RFID readers. Thanks to its reasonable cost and its ease of use, RFID is more and more adopted in many contexts, including robotics, where it is used as supplementary support for navigation and localization of robots. Indeed, when an RFID reader placed on the robot reads a tag marking a certain map point, specific algorithms can be used to estimate tag and/or robot position. Nevertheless, in most literature, commercial RFID devices, not specifically thought for robotic applications, are adopted, with consequent strong impact on overall system performance and robustness. In this paper, customized RFID reader antennas and platform-robust tags are designed and realized according to several requirements specifically individuated for the addressed application. Moreover, the new hardware has been tested on two practical cases related to tag and robot indoor localization, respectively. In spite of the use of rough-and-ready algorithms, the obtained results are impressive and demonstrate the goodness of the proposed solution.

Conventional RFID readers combine transmission (to the tag) and reception (from the tag) functions in a single physical device. In this paper we discuss the design and potential applications of a receive-only device, called "RFID listener", that decodes the signals from both the tag and the reader. This enables augmented RFID systems where one transmitter coexists with multiple listeners offering reception redundancy and diversity. We present a Software-Defined Radio (SDR) implementation of an RFID listener compliant with Gen2 standard, which can serve as a research tool for experimenting "on air" novel augmented RFID systems. Moreover, our listener can be used as a flexible and cheap protocol analyzer for conventional reader/tag systems. We present a test-bed setting where our listener and a conventional SDR reader are used in conjunction to measure separately the maximum downlink and uplink range. © 2011 IEEE.

The paper presents some experimental results obtained for RF-MEMS phase shifters in X-band. Two different phase shifters are considered: a loaded-line and a reflect-line phase shifter. Both devices have been monolithically manufactured on a 525 μm -thick high resistivity silicon substrate. The realized samples exhibit a good agreement between simulated and measured results. Moreover, excellent performance in terms of phase shift have been obtained for the two phase shifters: measurements show a phase error of 0.5% in the case of the loaded-line type and of 4.7% in the case of the reflect-line type.

Over the past decade, electromagnetic and communication science societies, along with improving the classical RFID technology, have put in a great deal of effort in designing novel and more complex UHF RFID tags with augmented capabilities. Novel tags offer additional functionalities besides identification by embedding sensors, actuators, and processing units. In this work an enhanced version of one of such devices, called SPARTACUS, is presented. While being completely passive, it conjugates identification, sensing, local computing, and actuation control and enables a proactive communication with any standard RFID reader. The paper presents details on a novel logical communication procedure over Low Level Reader Protocol (LLRP), besides discussing system validation and performance evaluation. © 2017 CCIS.

Passive RFID tags can be classified in terms of reading range. Short-range tags communicate with the reader up to a few centimetres. Medium-range tags reach almost 5 meters. Long-range tags work properly up to almost 12 meters. Nevertheless, the longer is the working distance, the larger is the tag size. In this work, a new passive UHF RFID tag has been designed, realized and tested. Based on the joint use of various design and miniaturization techniques, our device is as compact as a medium-range tag. The tag prototype has been extensively tested and compared with both a commercial medium-range tag with similar size and a well-performing long range tag. For all such tags, measurements of RSSI, working range, tag sensitivity and differential radar cross section have been carried out and compared. Results are impressive. In spite of the compactness of the proposed tag, its performance is appreciably better than the medium-range tag and even comparable with the tested long range one.

Performance evaluation of passive Radio Frequency IDentification (RFID) tags is a challenging task. In fact, tag performance depends on multiple factors such as the goodness of the conjugate matching between chip and antenna, the chip sensitivity, the strength and quality of the backscattered signal. Commercially available solutions for tag testing are very expensive and not totally flexible. In this work, we propose a novel approach for precise characterization of RFID tags based on Software-Defined Radio (SDR). We show how a cheap (below 1000$) and flexible SDR-based RFID reader can be turned into an accurate tool for measuring the tag sensitivity and differential radar cross-section. We test our platform by analyzing the performance of two built-in-lab tags: measurements show a strong agreement with theoretical and simulation results.

We all are aware of the huge amount of electromagnetic information and knowledge available in the Web, both in the form of PDF scientific papers, and in other forms (e.g., software, datasets). Similarly, we all have experienced the frustration of searching the Web for papers and other information, and getting useless or unsatisfactory results. All these limitations clearly demonstrate that information technologies (IT) need further progress so as to improve the efficiency of the mentioned processes. Indeed, there is fervid activity around this goal, and some interesting achievements have begun to appear in terms of search effectiveness and navigation satisfaction. Novel formats for representing scientific-paper contents are proposed, enhancing machine processing capability. However, embracing the new information technology proposals requires a cultural change from authors and from editors, and we cannot take it for granted that it will happen in the near future. Moreover, already-published papers should not be left out from approaching Web innovations. In this paper, we therefore focus both on the emerging technologies for generating more searchable files, and on those technologies allowing the transformation of existing PDF files into more-effective formats. These technologies need to be customized to each specific domain, thus rendering the codification of specific electromagnetic (EM) concepts of paramount importance. A use case is proposed on a specific EM example, so as to demonstrate the viability and effectiveness of the proposed approach.

Radio Frequency Identification is a wireless technology that is going to play a very important role as autoidentification solution for many application scenarios, where item-level traceability and high performance are crucial. Currently, some guidelines suggest the use of passive Ultra High Frequency tags for this kind of tracing system. In particular, Near Field UHF tags have also been suggested to face critical conditions such as the presence of liquids. Unfortunately, not all the requirements that a tag should satisfy in the different steps of the supply chain, can be met by general-purpose commercial tags in UHF band, both Near Field and Far Field. This is due to the effect on the performance of the presence of metals and liquids, as well as to the very stressful conditions such as high scanning speed, possible misalignment between tag and reader antennas, and multiple reading of tags. In this paper, we are presenting the main features that a far field UHF tag should own in order to work properly in the whole supply chain. A tag satisfying all the individuated requirements has been also realized and tested to trace some critical pharmaceutical products, containing metals and liquids, and has been compared with some commercial UHF tags, both Near Field and Far Field. The very impressive results clearly demonstrate that well-designed ad hoc Far Field UHF tags effectively improve the performance of any item-level tracing system.

In this paper, a rigorous procedure for the circuit-level analysis and design of entire systems, developed to provide power wirelessly, is presented. A unified theoretical approach is first introduced, based on a two-port-equivalent circuit representation, to describe the wireless power transfer link when the transmitter and the receiver are either in the near-field or in the far-field region reciprocally. This approach allows one to compute in a straightforward manner the system figure of merit, namely the power transfer efficiency. Specific guidelines for the two configurations are then intensively discussed together with the adopted software tools based on the combination of full-wave analysis and nonlinear harmonic balance techniques. Several practical examples based on this design procedure are presented, demonstrating predicted and experimental behavior of unconventional devices for both near-field and far-field power transfer usage.

Radio-Frequency Identification (RFID) technology is a consolidated example of electromagnetic system in which passive labels equipped with flexible antennas, called tags, are able to use a portion of the electromagnetic energy from the reader antennas, power-up their internal circuitry and provide the automatic identification of objects. Being fully-passive, the performance of RFID tags is strongly dependent on the context, so that the selection of the most suitable tag for the specific application becomes a key point. In this work, a cost-effective but accurate system for the over-The-Air electromagnetic characterization of assembled UHF RFID tags is firstly presented and then validated through comparison with a consolidated and diffused measurement systems. Moreover, challenging use-cases demonstrating the usefulness of the proposed systems in analyzing the electromagnetic performance of label-Type tags also when applied on materials on different shape or embedded into concrete blocks have been carried out. © 2017 CCIS.

In the last years, the continuous demand for smart applications in the Internet of Things context is leading to the develop of novel and more complex UHF RFID tags with augmented capabilities. Novel tags offer additional functionalities besides identification by embedding sensors, actuators, and processing units. In this work a new kind of device, called SPARTACUS, is presented. While being completely passive, it conjugates identification, sensing, local computing, and actuation control and enables a proactive communication with any standard RFID reader. Thanks to an accurate electromagnetic design and exploiting polarization diversity of two antennas performing both energy harvesting and communication, SPARTACUS ensures compactness, energy-efficiency, and ease of use. The paper presents detailed design of the device, besides discussing system validation and performance evaluation. © 2015 IEEE.

A self-powered autonomous RFID device with sensing and computing capabilities is presented in this paper. Powered by an RF energy-harvesting circuit enhanced by a DC-DC voltage booster in silicon-on-insulator (SOI) technology, the device relies on a microcontroller and a new generation I 2C-RFID chip to wirelessly deliver sensor data to standard RFID EPC Class-1 Generation-2 (Gen2) readers. When the RF power received from the interrogating reader is -14 dBm or higher, the device, fabricated on an FR4 substrate using low-cost discrete components, is able to produce 2.4-V DC voltage to power its circuitry. The experimental results demonstrate the effectiveness of the device to perform reliable sensor data transmissions up to 5 meters in fully-passive mode. To the best of our knowledge, this represents the longest read range ever reported for passive UHF RFID sensors compliant with the EPC Gen2 standard.

The paper presents a novel multilayer micro-ring structure suitable to be used as THz emitter or detector. The realization process exploits the self-rolling properties of a suspended InGaAs/GaAs bi-layer obtained by controlled strain release of a thin film from a substrate. Numerical and preliminary experimental results will be presented and discussed. It is demonstrated that the proposed approach is an optimum candidate for the design of very high-frequency resonators.

This paper proposes a novel harvester for sensors powering by spurious electromagnetic emissions from compact fluorescent lamps. The proposed device is based on a magnetic coupling and consists of a resonant loop and an RF-to-DC rectifier. Experimental results are reported and discussed. It is shown that up to 0.61 mW can be generated from a 30 W compact fluorescent lamp, thus demonstrating that the proposed harvester is an optimum candidate for powering low-power sensors.

A cost-effective integration of passive UHF RFID tags and sensors is still a challenge. In such a field, authors have already proposed a label-type multi-antenna Sensor-Tag, an RFID device accepting as input a generic sensor and allowing the transmission of the measured data towards a standard RFID reader. In this work a new enhanced version of Sensor-Tag is presented. It is based on optimized tag antennas designed by taking into account both size constraints and coupling effects. Compared with the old version, an appreciable size reduction is obtained and the working distance doubled, being now as good as a long range passive UHF tag. © 2001-2012 IEEE.

Radio Frequency Identification (RFID) technology is playing a crucial role for item-level tracing systems in healthcare scenarios. The pharmaceutical supply chain is a fascinating application context, where RFID can guarantee transparency in the drug flow, supporting both suppliers and consumers against the growing counterfeiting problem. In such a context, the choice of the most adequate RFID tag, in terms of shape, frequency, size and reading range, is crucial. The potential presence of items containing materials hostile to the electromagnetic propagation exasperates the problem. In addition, the peculiarities of the different RFID-based checkpoints make even more stringent the requirements for the tag. In this work, the performance of several commercial UHF RFID tags in each step of the pharmaceutical supply chain has been evaluated, confirming the expected criticality. On such basis, a guideline for the electromagnetic design of new high-performance tags capable to overcome such criticalities has been defined. Finally, driven by such guidelines, a new enhanced tag has been designed, realized and tested. Due to patent pending issues, the antenna shape is not shown. Nevertheless, the optimal obtained results do not lose their validity. Indeed, on the one hand they demonstrate that high performance item level tracing systems can actually be implemented also in critical operating conditions. On the other hand, they encourage the tag designer to follow the identified guidelines so to realize enhanced UHF tags.

Radio-frequency identification (RFID) is one of the most promising technologies to enable new smart applications in the framework of the Internet of Things (IoT). Nevertheless, from the electromagnetic point of view, the performance of the RFID tags is generally dependent on the context, so that the selection of the most suitable tag for the specific application becomes the key point. In this work, a cost-effective but accurate characterization system for the performance evaluation of UHF RFID tags is first presented and then validated on the IoT-related relevant case of RFID-based interaction with buildings. © 2016 University of Split, FESB.

An experimental approach is proposed to validate the theoretical energy-based considerations for wearable UHF RFID antenna design. On the basis of numerical analysis, it has been shown that wearable antennas presenting an energy density peak far from the antenna border are more robust with respect to the distance from the human body. A flexible and cost-effective RFID tag characterization and performance evaluation platform is used here to validate the theoretical approach by considering a grounded UHF RFID tag. © 2017 ACES.

This paper presents an experimental study of the performance of a wireless resonant energy link for implantable biomedical devices. More specifically, the proposed system consists of two planar resonators: a primary resonator that is connected to a power source and operates outside the body, and a secondary resonator that is connected to the implanted device and operates inside the body. Each resonator is a planar spiral resonator; the wireless power transmission is obtained by exploiting the magnetic coupling between the two resonators when they are operating at small distances. A prototype working in the ISM band centered at 434MHz has been developed and analyzed. Reported results confirm that the proposed system is a viable solution for wirelessly providing implantable devices with the power necessary for operation.

Radio Frequency Identification is going to play a very important role as auto-identification solution for many application scenarios, where item-level tagging and high performance are crucial. In such a context, the use of passive Ultra High Frequency (UHF) tags is strongly suggested but, unfortunately, general-purpose commercial tags could not meet all the requirements in presence of critical operating conditions, including the presence of metals and liquids, the misalignment between tag and reader antennas, and the need of multiple reading of tags. In this paper, the main features that a UHF tag should own to work properly in the whole supply chain are presented. A tag, named below Enhanced tag, satisfying all the individuated requirements has been also realized and validated in a controlled test environment simulating the pharmaceutical supply chain. Tests have been focused on the above-mentioned critical conditions. The performance of the Enhanced tag, in terms of successful read rate, has been compared with that of some commercial Far Field and Near Field UHF tags. The experimental results are impressive and clearly demonstrate that ad hoc Far Field UHF tags are able to effectively solve many of the performance degradation problems affecting general-purpose tags. Finally, the proposed tag has been also tested in extreme conditions, applying it directly on Tetra Pak packages containing liquid, with interesting results in terms of platform-tolerant features.

This paper investigates the use of different techniques and conductive materials for the fabrication of textile patch antennas. Experimental results referring to the use of a conductive thread, an adhesive copper tape and an adhesive conductive non-woven fabric are reported and discussed. Reported results demonstrate the suitability of the proposed prototypes to be used for wearable applications. © 2013 European Microwave Association.

This work presents three different fully-passive RFID devices with sensing capabilities. The first one, not new in literature, is based on a multi-ID approach while the other two are quite more complex platforms which embed data gathered from on-board and/or external sensors directly into the RFID EPC code. Satisfactory operating range, computing capability, memory accessibility, and cost are the main strengths making the three devices definitely suitable for a wide array of applications.

The solution of large and complex electromagnetic (EM) problems often leads to a substantial demand for high-performance computing resources and strategies. This is true for a wide variety of numerical methods and applications, ranging from EM compatibility to radio-coverage, circuit modeling, and optimization of components. In the last decades, graphics processing units (GPUs) have gained popularity in scientific computing as a low-cost and powerful parallel architecture. This paper gives an overview of the main efforts of researchers to port computational electromagnetics (CEM) codes to GPU. Moreover, GPU implementation aspects of two well-known techniques, namely the finite-difference time domain (FDTD) and the method of moments (MoM), are investigated. The impressive speed-ups achieved (up to 60× and 25× for FDTD and MoM, respectively) demonstrate the effectiveness of GPUs in accelerating CEM codes. © 2012 John Wiley & Sons, Ltd.

Radio Frequency Identification is a wireless technology that is going to play a very important role as auto-identification solution for many application scenarios, where item-level traceability and high performance are crucial. Currently, some works suggest the use of passive Ultra High Frequency (UHF) tags but, unfortunately, not all the requirements can be met by general-purpose commercial tags in presence of critical operating conditions (e.g. metals and liquids, misalignment between tag and reader antennas, and multiple reading of tags). In this paper, the main features that a Far Field UHF tag should own in order to work properly in the whole supply chain are presented. A tag satisfying all the individuated requirements has been also realized and validated in a controlled test environment able to simulate the pharmaceutical supply chain. Tests have been focused on the above mentioned critical conditions. The performance of the Enhanced tag, in terms of successful read rate, has been compared with those of some commercial Far Field UHF tags. The experimental results are impressive and clearly demonstrate that ad hoc Far Field UHF tags are able to effectively solve many of the performance degradation problems affecting general purpose tags.

In this letter, an improved version of a recently published battery-less augmented radio frequency identification device enabling a tag-reader cooperative approach is presented. Based on a specifically designed physical layer implementing a logical communication procedure over low-level reader protocol, the device is now capable to react to the reader solicitations by reasoning, asking for extra info, taking autonomous decisions, piloting actuators, and generating alerts. Tests performed in the building automation context demonstrate the capability of the proposed device of reasoning jointly with the reader and changing its behavior according to logical and physical events occurring in the surrounding environment. © 2016 IEEE.

Radio-frequency identification (RFID) is one of the most promising technologies to enable new smart applications in the framework of the Internet of Things (IoT). Nevertheless, from the electromagnetic point of view, the performance of the RFID tags is generally dependent on the context, so that the selection of the most suitable tag for the specific application becomes the key point. In this work, a cost-effective but accurate characterization system for the performance evaluation of UHF RFID tags is first presented and then validated on the IoT-related relevant case of RFID-based interaction with buildings. © 2016 IEEE.

In many practical applications, the item-level tracing systems based on Radio Frequency Identification (RFID) technology is becoming more and more essential. Nevertheless, the requirements that an RFID tag should satisfy in the different steps of the supply chain, cannot be met by general purpose commercial tags, whose adoption would lead to low-performance systems. In this paper, we are presenting the properties of an ad hoc Ultra High Frequency (UHF) tag, designed and realized in order to work properly in the entire supply chain. The proposed tag has been tested to trace some critical pharmaceutical products, containing metals and liquids, and has been compared with a pre-selected commercial tag. Both tags mount the same chip. The very impressive results, reported in this paper, clearly demonstrate that well-designed ad hoc tags effectively improve the performance of any item-level tracing system.

Radio Frequency Identification (RFID) technology is increasingly adopted in many contexts where tags customized for specific applications are needed. Nevertheless, in many practical cases, electromagnetic labs which realize RFID tags use either very rudimentary methods, by shaping the tag antenna on a copper film through a handy cutter, or photolithography methods based on rigid PCB. In this work two innovative prototyping techniques suitable for built-in-lab flexible tags based on are presented. The former is based on the joint use of solid ink printers and flexible PCBs, the latter consists of using a cutting plotter on adhesive copper. A rigorous electromagnetic validation is then proposed, demonstrating the appropriateness of the proposed solutions.

Radio Frequency Identification (RFID) and Wireless Sensor Networks (WSNs) have received an ever-increasing attention in recent years, mainly because they represent two of the most important technologies enabling the Internet of Things vision. Although designed originally with different objectives, WSN and RFID represent two complementary technologies whose integration might increase their functionalities and extend their range of applications. However, important technological issues must still be solved in order to fully exploit the potentialities offered by such integration. In this work, an innovative RFID-WSN integration approach is presented and validated. It relies on the interconnection of a new-generation, long-range, EPCglobal Class-1 Generation-2 Ultra-High-Frequency (UHF) RFID tag with a commercial WSN node via the I2C interface. Experimental results have demonstrated the effectiveness of the proposed approach compared to existing solution in the literature. Interesting application scenarios enabled by the proposed RFID-WSN integration approach are briefly summarized at the end of the paper.

Healthcare represents one of the most promising sectors for future RFID applications. RFID, indeed, candidates as a natural solution to a large amount of biomedical problems, from care giving to telemedicine. Nevertheless, for a large scale diffusion into this market, the integration of RFID systems with a sensor network through the introduction of novel RFID tags integrated with sensors and capable to transmit the measured physical parameter, could be the turnpoint. Nevertheless, although some RFID tags capable to transmit sensor-like information are already on the market, only a restrict number of sensors, such as those for temperature or pressure measurement, can be easily miniaturized and embedded in the RFID chip. The integration of more complex sensors, such as those for the healthcare domain, is complicated and extremely expensive. In this paper, a cost-effective general-purpose multi-ID tag, called S-Tag, is proposed. It can be connected to generic sensors, and is capable to transmit a proper combination of ID codes depending on the actual value at its input. The S-Tag has been extensively validated by testing its performance when connected to different kinds of sensors. Moreover, the test case of the remote and automatic S-Tag-based monitoring of the glycemia levels of diabetic patients has been studied, demonstrating the effectiveness of the S-Tag even in realistic scenarios.

This work describes a Smart Hospital System (SHS) based on the integration of Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) and IEEE 802.15.4 Wireless Sensor Network (WSN) technologies. SHS is able to provide patient localization, tracking, and monitoring services within hospitals or nursing institutes through the deployment of a heterogeneous network of RFID-WSN nodes relaying data to a central server. A set of software applications based on RESTful Java and database Push Notification (PN) technologies has been designed, implemented, and installed on the central in order to manage alert events (e.g. patient falls) and promptly inform the nursing staff through an iOS mobile app which has been designed ad hoc for the smart hospital scenario.

The recent advent of general-purpose graphics-processing units (GPGPUs) as inexpensive arithmetic-processing units brings a relevant amount of computing power to modern desktop PCs. This thus providing an interesting pathway to the acceleration of several numerical electromagnetic methods. In this paper, we explain how to exploit GPGPU features by examining how the computational time of the Finite-Difference Time-Domain Method can be reduced. The attainable efficiency is demonstrated by providing numerical results achieved on a two-dimensional study of a human-antenna interaction problem.

This paper proposes a rectifying antenna (rectenna) for operation in the ISM (Industrial, Scientific and Medical) band centered at 2.45 GHz. It consists of a modified circular monopole loaded with a rectangular ring and a half-wave rectifier. Numerical and experimental data are reported and discussed. From measurements, it is demonstrated that, when the power density incident on the monopole is 155 μW/cm², the device here presented exhibits values of the RF-to-DC conversion efficiency higher than 30 % in the frequency range 2.35-2.5 GHz with a maximum of about 50 % at 2.45 GHz.

We present the software-defined radio (SDR) implementation of a Radio Frequency IDentification (RFID) Listener, a passive receive-only device that decodes the signals exchanged between the RFID Reader and the interrogated Tag following the Electronic Product Code Class-1 Generation-2 standard. Our RFID Listener is based on the open-source project GNU Radio. It provides complete flexibility and full control over the entire protocol stack down to the physical layer. As such, it can be used as a powerful but inexpensive tool for testing and measuring the performance of RFID systems in real operating conditions. In this paper, we leverage the SDR Listener for a number of experiments that, taken collectively, are illustrative of the potential of such tool for RFID research. First, we use it to test comparatively different timing recovery schemes for the reception of the Tag signal in uplink, through the analysis of bit-error statistics measured experimentally. We find that the scheme proposed by Harris and Rice based on polyphase filter bank displays excellent performance in this context, very close to the theoretical bound and with a gain of 5 dB over the more common Mueller and Muller scheme. Second, we use the Listener to evaluate the impact of frequency nulls in the uplink RFID channel for different indoor scenarios. We find that frequency nulls are pronounced particularly in the presence of metal objects and obstructions of the Fresnel zone, but frequency hopping is effective in counteracting the problem. Our experiments show that the signal backscattered by a passive Tag can be correctly received up to a distance of 35 m, with low-cost equipment and without highly directional antennas.

This paper presents a novel logo-shaped antenna. The proposed antenna has been fabricated by using a conductive non-woven textile on a layer of jeans. Experimental data referring to a prototype working at 1.8 GHz are presented and compared with numerical results. A relative bandwidth of about 70% and a dipole-like radiation pattern is demonstrated.

In this paper a wireless power transfer resonant link using inductive coupling is considered and analyzed on the basis of an artificial transmission line approach. More specifically, a periodic network consisting of inductively coupled LC resonators is studied. It is demonstrated that the analyzed system exhibits a pass-band characterized by negative effective parameters (i.e., a double negative pass-band). In order to validate the proposed approach, comparisons with experimental data and circuital simulations are reported and discussed.

The huge improvement in UHF radio-frequency identification (RFID) technology, also driven by the vision of the Internet of Things, is leading to a widespread diffusion of several kinds of passive RFID tags. In fact, depending on the specific application, tags must satisfy key requirements in terms of size, thickness, shape, robustness, cost, working range, bandwidth, antenna directivity, platform tolerance, polarization, and so on. In such a scenario, the design of a specific application-oriented tag by an RF designer as well as the careful selection among commercially available solutions by system integrators rather than final users needs a dedicated measurement system enabling a rapid and cost-effective procedure for the on-air performance evaluation of RFID tags. Nevertheless, the design of such a system is not trivial, as tag performance depends on multiple major factors, such as chip sensitivity, quality of the chip-antenna conjugate matching, and antenna radiation properties. In this paper, after a theoretical formulation, an accurate, flexible, robust, and cost-effective RFID tag characterization and performance evaluation platform is presented and validated. It allows the calculation of the main metrics characterizing an RFID tag as a function of the tag activation power threshold when varying both interrogation frequency and tag orientation. The system is validated on both specifically designed and commercial RFID tags in terms of sensitivity, working range, and tag antenna radiation pattern: measurements show strong agreement with the theoretical and simulation results. © 1963-2012 IEEE.

Radio-frequency identification (RFID) technology is a consolidated example of wireless power transfer system in which passive electromagnetic labels called tags are able to harvest electromagnetic energy from the reader antennas, power-up their internal circuitry and provide the automatic identification of objects. Being fully passive, the performance of RFID tags is strongly dependent on the context, so that the selection of the most suitable tag for the specific application becomes a key point. In this work, a cost-effective but accurate system for the over-the-air electromagnetic characterization of assembled UHF RFID tags is firstly presented and then validated through comparison with a consolidated and diffused measurement systems. Moreover, challenging use-cases demonstrating the usefulness of the proposed systems in analyzing the electromagnetic performance of label-type tags also when applied on different material or embedded into concrete structures have been carried out.

This work focuses on the use of metal foams, a relatively new class of materials, for high added-value electromagnetic (EM) shields. First, the Shielding Effectiveness (SE) of aluminum foam slabs is experimentally evaluated, showing very good shielding properties. Successively, accurate numerical models of metal foams are proposed and used in a proprietary Variable-Mesh Parallel Finite Difference Time Domain code, in order to characterize the EM properties of slabs of such materials. Afterwards, a third approach is adopted. It consists in the application of the effective medium theories in order to obtain an analytical EM model of the metal foams; this way, their SE can be evaluated with a negligible computational time by using common mathematical tools. Finally, a methodology to design/analyze customized metal foams for EM shield applications is suggested. It takes advantage from the joint use of the numerical and analytical presented approaches, thus allowing a computationally effcient evaluation of SE and other electromagnetic properties of metal foams. Results demonstrate the suitability of metal foam structures for effective EM shielding in many industrial applications, as well as the accuracy of the proposed analytical and numerical approaches.

In this study, the characterisation of three-dimensional (3D)-printed substrates in terms of relative dielectric constant and loss tangent by using the T-resonator method is proposed. In particular, after the theoretical formulation of this method, the T-shape structure has been realised and its effectiveness in characterising also 3D-printed substrates in the frequency range between 800 and 5000 MHz has been experimentally demonstrated. Therefore, the T-resonator has been used to perform the microwave characterisation in terms of both dielectric constant and loss tangent of 3D-printed polylactic acid substrates when varying the infill percentage. Obtained results have been first summarised and discussed, and then used to realise an example of 3D-printed ultra-high-frequency radio-frequency identification tag, thus demonstrating the suitability of 3D-printable materials to be used as dielectrically controlled substrates for low-cost and high-performing electromagnetic applications. © The Institution of Engineering and Technology 2017.

This paper presents a novel antenna for Ground Penetrating Radar (GPR) applications. It consists of two crossed bowtie antennas loaded with an annular ring. Numerical and experimental results are reported demonstrating that the proposed antenna exhibits both a broadband impedance bandwidth and very good radiation properties

This paper describes how to publish data coming from scattered and heterogeneous Electromagnetic (EM) field sensing systems in compliance with novel knowledge management techniques. Ontological modeling and Linked Data Principles have been exploited to interlink and organize, from a semantic point of view, measurement data with additional information describing sensors, measurement sites and techniques, emitting sources and devices, etc. From the very first achieved results, the proposed approach exhibits many appealing features. For instance, the possibility to seamlessly access different legacy data sources or to create semantic relationships across related scientific areas. Therefore, traditional data publication techniques for EM pollution monitoring campaigns can now be thought-back and broadened by adding new features to reach more variegated categories of users rather than only technicians or managing authorities

This paper presents a rectifying antenna (rectenna) for the harvesting of the microwave energy associated to UHF (Ultra- High Frequency) Radio Frequency IDentification (RFID) systems. The proposed device uses a capacitively loaded T-shaped monopole with a coplanar waveguide feeding line as receiving antenna and a five-stage voltage multiplier as rectifier. Experimental results demonstrating an RF-to-DC conversion efficiency of about 54% with an input power density of 80W/cm2 will be presented and discussed.

In this paper, we describe an accelerated implementa- tion of the Method of Moments (MoM). A framework is proposed, exploiting the graphics processing unit (GPU) computing power by means of the software platform compute unified device archi- tecture (CUDA). The mixed-potential integral-equation formula- tion, applied to microstrip circuit modeling, is adopted, and both the impedance matrix computation and the linear system solution of the MoM are accelerated. The latter point has been handled by considering both a direct dense (LU-based) and an iterative sparse (bi-conjugate gradient stabilized) solver. The best suited method is selected automatically during a thresholding phase, which renders the impedance matrix as sparse as possible. The effectiveness of the GPU-enabled MoM has been extensively tested in the analysis of planar circuits and components. The results achieved confirm the validity, accuracy, and high performance of the proposed ap- proach.

Radio frequency identification (RFID) technology is more and more adopted in a wide range of applicative scenarios. In many cases, such as the tracking of small-size living animals for behaviour analysis purposes, the straightforward use of commercial solutions does not ensure adequate performance. Consequently, both RFID hardware and the control software should be tailored for the particular application. In this work, a novel RFID-based approach enabling an effective localization and tracking of small-sized laboratory animals is proposed. It is mainly based on a UHF Near Field RFID multiantenna system, to be placed under the animals’ cage, and able to rigorously identify the NF RFID tags implanted in laboratory animals (e.g., mice). Once the requirements of the reader antenna have been individuated, the antenna system has been designed and realized. Moreover, an algorithm based on the measured Received Signal Strength Indication (RSSI) aiming at removing potential ambiguities in data captured by the multiantenna system has been developed and integrated. The animal tracking system has been largely tested on phantom mice in order to verify its ability to precisely localize each subject and to reconstruct its path. The achieved and discussed results demonstrate the effectiveness of the proposed tracking system.

The numerical calculation of the Specific Absorption Rate (SAR) averaged over a certain tissue mass is a common practice when evaluating the potential health risk due to the human exposure to electromagnetic sources. Nevertheless, SAR values are strongly influenced by many factors such as, for instance, the shape of the volume containing the reference mass, the spatial discretization step, or the treatment of internal air, just to mention some of them: different choices can induce signi¯cant discrepancies. In this work, an overview on some of the most commonly adopted SAR algorithms is firstly presented, and a discussion on their potential differences reported. Then, based on a spherical volume approach, some new algorithms are proposed. All the algorithms are then used to evaluate the SAR both in arti¯cially generated test cases and in some practical human-antenna interaction problems. The result comparison highlights relevant discrepancies and enforces the necessity of a reasoned standardization of the techniques for the SAR calculation.

In this article, the use of metal foams for shielding problems is investigated on the bases of an effective medium approach. Specifically, a shielding effectiveness analysis has been performed by modeling metal foams as a homogeneous medium described by a plasma dispersion profile.The suggested approach is experimentally validated demonstrating that metal foams behave like a plasma medium, with a plasma frequency in the microwave range. The proposed effective medium approach has also been implemented both with a proprietary and with a commercial full-wave simulator. Results demonstrate that, by using the plasma model, general electromagnetic analysis of metal foams can be performed with common simulators and with affordable computational efforts.

Non-radiative Wireless power transfer (NR-WPT) is currently receiving considerable attention in very different application scenarios. To design optimum solutions, a systematic approach based on circuit theory is needed and not yet available in the literature. In this chapter, by using a network formalism, the WPT link is modeled as a two-port network and a methodology to derive an equivalent circuit is proposed. This allows to compute in a rigorous and general way the maximum achievable performance for any given WPT link. The latter can be expressed in terms of either maximum power transfer efficiency (MPTE), or maximum power delivered to the load (MPDL), or by any suitable combination of the two. This chapter provides a comprehensive theoretical and general framework to predict such performance for both inductive and capacitive coupled links. In order to facilitate a practical implementation, both impedance and admittance matrix representations are discussed and computational examples are provided.

The emerging radio frequency identification (RFID) technology is more and more adopted in a huge range of application scenarios. Nevertheless, in many of them, a real added value would be given by the use of novel RFID devices which, while ensuring cost effectiveness and ease of use, also guarantee augmented functionalities, such as on-board sensing and computation. In such a field, this work presents the progress in the design of smart, multi-function, RFID-enabled devices at the Electromagnetic Lab Lecce. Specifically, the preliminary prototypes of SPARTACUS and RAMSES, which are the two UHF RFID tags with augmented functionalities introduced in our earlier works, have been significantly improved in terms of compactness, antenna design, sensing and computing capabilities. The achieved operating ranges and sensing performance are the main strengths making the two devices definitely suitable for a wide array of applications. © 2014 European Microwave Association.

This paper presents a novel low-profile antenna with a broadside radiation. The proposed design strategy consists in modifying the layout of a classical Vivaldi antenna, thus resulting in compact dimensions and a broadside radiation pattern. Two different ways of implementing the proposed design approach are presented and discussed. More specifically, experimental data referring to two prototypes on a FR4 substrate with an operating frequency of 2.45 GHz are reported. The first layout has approximately the same dimensions of a Vivaldi antenna and a directivity of about 7 dBi, the second one has more compact dimensions (the dimensions are smaller than the ones of a standard patch antenna) and a directivity of about 5 dBi.

The use of RFID as supplementary support for navigation of robots is not new in literature. Nevertheless, commercial RFID devices are not thought for robotic applications, with consequent impact on the performance of the system. In this work, based on specific requirements individuated and discussed, ad-hoc RFID reader antennas and platform-robust tags are designed, realized and tested on a practical case study. The obtained impressive results demonstrate the appropriateness of the proposed approach.

The RFID-based sensor networks are becoming increasingly appealing because of the perspective of applicability at a reasonable cost. Nevertheless, they require the integration of passive RFID tags and sensors. Even if technically possible, this integration is still limited both in type and cost. In fact, the embedding implies strict constraints in terms of size and energy consumption of the sensor. Moreover, the extra microwave and digital circuitry cause the sharp increase of the intrinsic value of the tag. This last aspect is crucial because the most attractive feature of a passive RFID tag is its cost-effectiveness other than its ease of use. In this work we propose a new version of our previously published label-type Sensor Tag, an RFID device that accepts as an input a generic sensor and allows the transmission of the measured data. The new enhanced sensor tag is based on four optimized antennas designed by taking into account the size constrains and the mutual coupling effects. The size reduction, compared with the old version, is appreciable, and the working distance is now as good as a long range passive UHF tag. © 2011 IEEE.

In this article we adopt the graphical processing units as a low-cost and efficient solution of challenging electromagnetic numerical problems. Based on the compute unified device architecture, an optimized method of moments algorithm has been implemented which adopts direct solvers based on LU decomposition. Numerical results obtained on the practical case of a patch antenna analysis demonstrate the high performance of the approach

In this work SPARTACUS a novel Passive RFID augmented device useful to be adopted in challenging IoT contexts like the building automation is presented. While being completely passive, the novel RFID tag conjugates identification, sensing, local computing, and actuation control and enables a proactive communication with any standard RFID reader. Thanks to a specific electromagnetic design and exploiting polarization diversity of two antennas performing both energy harvesting and communication, SPARTACUS ensures compactness, energy-efficiency, and ease of use. © 2016 University of Split, FESB.

In this letter, a recently proposed power efficient wireless sensor network node mounting a pattern-reconfigurable antenna has been enhanced through the design and use of a wake-up circuit based on a RF power meter. In such a way, the RF frontend is smartly activated only when a potential communication is sensed, thus even more reducing the node power consumption. Tests demonstrate that the wake-up circuit allows a reasonable working distance of 55 m. Moreover, a reduction of the power consumption of ∼ 21 % with respect to our previous solution, and of ∼ 40 % with respect a standard node, is obtained.

Performance evaluation of passive Radio Frequency Identification (RFID) tags is a crucial but challenging task. In fact, tag performance depends on multiple factors like the goodness of the conjugate matching between chip and antenna, the chip sensitivity, and the strength and quality of backscattered signal. Moreover, passive RFID tags lack wired connectors and therefore cannot be directly interfaced with conventional measurement instruments. Some solutions for tag testing and performance evaluation are commercially available on the market, but they are expensive and not totally flexible. In this work we propose a novel approach to the problem of tag performance analysis based on Software-Defined Radio (SDR). We show that a SDR tool for UHF RFID reading allows the characterization of tag performance by any metric and for any operating frequency, with a total equipment cost below 1000 USD. We present the methodology to measure tag sensitivity, differential radar cross-section and Signal-to-Noise ratio, and provide numerical results for five different tags. © 2011 IEEE.

The adoption of solutions based on Radio Frequency IDentification technology in a wide range of contexts is a matter of fact. In many situations, such as the tracking of small-size living animals, the straightforward use of commercial systems does not ensure adequate performance. Consequently, both the RFID hardware and the software control platform should be tailored for the particular application. In this work, the specific requirements of Near Field Ultra High Frequency RFID reader antennas suitable for small-size animal localization and tracking are identified and a control system in a LabVIEW environment is designed. Afterwards, both hardware and software solutions have been implemented and validated. In particular, an algorithm based on the measured Received Signal Strength Indication, in order to obtain precise localization data, was developed and validated. Finally, the set-up of a first working prototype involving built-in-lab reader antennas has been completed and tested. The achieved results prove the effectiveness of the proposed tracking system.

Maximizing the Radio Frequency Identification (RFID) performance is one of the main challenges in application domains, such as logistics and supply chain management, where the undesired effect of Tag collisions can significantly degrade the speed of the inventory process. The dominating UHF EPC Class-1 Generation- 2 (EPC Gen2) protocol only specifies collision avoidance algorithms but makes no provision for collision resolution. In this paper, performance enhancement of the EPC Gen2 standard exploiting Tag collision recovery is demonstrated, for the first time, in real time with measurements. Three simple and effective approaches to handle successful Tag acknowledgments of recovered collided packets are proposed and implemented on a software-defined Reader and programmable Tags. The attained benefits over the conventional EPC Gen2 MAC scheme are significant: the throughput per time slot is increased by 72% while the overall time required to inventory the Tag population is reduced by 26%. The effectiveness of the proposed approach and the validity of the achieved results are confirmed by the good agreement with simulations reported in the literature.

Performance evaluation of passive Radio Frequency IDentification (RFID) Tags is a very challenging task and commercially available solutions for Tag testing are very expensive and not totally flexible. In this work, we propose a novel approach for the characterization of RFID Tags with Software-Defined Radio (SDR). We show how a cheap (below 1000$) and flexible SDR-based RFID Reader can be turned into an accurate tool for measuring the goodness of the conjugate matching between the RFID chip and the antenna which primarily affects the Tag sensitivity. We test our platform by analyzing the performance of two built-in-lab Tags: measurements show a strong agreement with theoretical and simulation results.

The use of Radio Frequency IDentification (RFID) technology in a large array of contexts is a matter of fact. In many cases, such as in robotic applications, the RFID tags should satisfy specific requisites so that read range, platform robustness, radiation properties, cost, and size must be properly taken into account during the design phase. In this work, the specific requirements of tags for RFID-assisted localization and navigation of mobile robots are highlighted and discussed. On such basis, an ad-hoc platform-robust RFID tag is designed, realized and exhaustively tested through both simulations and measurements. The achieved results are impressive and demonstrate the appropriateness of the proposed tag to operate in application scenarios where performance stability is mandatory.

Based on a magnetic coupling, this paper presents a novel device for power generation by spurious electromagnetic emissions from compact fluorescent lamps. The proposed scavenger consists of a resonant loop and an RF-to-DC voltage converter. Results of experimental tests performed with a 30 W compact fluorescent lamp are reported and discussed. It is shown that 0.61 mW can be generated, thus demonstrating the suitability of the proposed device for powering low-consumption sensors.

Most of the articles in the EM Programmers Notebook column address either computational electromagnetics or electromagnetic simulation of one form or another. The article in this issues EM Programmers Notebook column instead considers new radio-frequency identification tags; these tags contain some embedded local processing capability and provide several new functionalities, such as autonomous reasoning, self-configurability, sensing, and actuation. In particular, the coding of Internet of Things applications for these new tags is discussed. As always, thanks to all of the contributors, and a special note of thanks to Alessandra Esposito and Luciano Tarricone, who have been regular contributors to this columnthis is their seventh contribution since 2003. © 2015 IEEE.

As a matter of fact, electromagnetic labs involved in label-type UHF RFID tags design, realize their tag prototypes making use of either very rudimentary methods, by shaping the tag antenna on a copper film through a handy cutter, or photolithography methods based on rigid PCB, which give out non-flexible devices. In this work two innovative prototyping techniques suitable for built-in-lab flexible tags are presented. The former method is mainly based on the use of a cutting plotter to precisely shape the tag antenna on adhesive copper tapes. The latter makes jointly use of flexible PCBs and solid ink printers. Once introduced and discussed, the new prototyping methods have been electromagnetically characterized and results have been compared with the canonical photolithography. At the end of the paper, the very challenging test-case of the practical realization of a flexible Sensor-Tag is presented. The measured and shown performance confirms the appropriateness of the proposed prototyping techniques even for complex RFID-based structures.

Quality control of vegetableoils is becoming more stringent, and strict laws are being enforced, especially for avoiding adulteration. The public bodies that are responsible for the prevention of the adulteration of foodstuffs necessitate methods of analysis that could facilitate large-scale in situ controls. Similarly, oil producers constantly strive to speed up internal qualitycontrol. As a direct consequence, there is an increasing demand for innovative methods of analysis that could guarantee real-time in situ monitoring and provide adequate accuracy. On such bases, the present work addresses the possibility of monitoring qualitative characteristics of vegetableoils through microwavedielectricspectroscopy. To this purpose, the Cole–Cole dielectric parameters of different vegetableoils are evaluated through an innovative automatable procedure that suitably combines traditional TDR measurements, SOL calibration, frequency domain processing, TL modelling and, finally, a minimization routine. The proposed procedure is carried out first on different “pure” oils and, secondly, on some oil mixtures. The obtained results confirm that different dielectric characteristics are associated with different oils, thus confirming the considerable potential of dielectricspectroscopy for quality and anti-adulterationcontrol purposes, especially in view of practical applications.

This paper presents a radio frequency identification (RFID) augmented module for smart environmental sensing (RAMSES), which is a fully passive device with sensing and computation capabilities conceived to explore novel and unconventional RFID applications. RAMSES implements an RF energy-harvesting circuit enhanced by a dc-dc voltage booster in silicon-on-insulator technology, an ultralow-power microcontroller, temperature, light, and acceleration sensors, and a new-generation I2C-RFID chip to wirelessly deliver sensor data to standard RFID EPCglobal Class-1 Generation-2 readers. A preliminary RAMSES prototype, fabricated on a printed circuit board using low-cost off-the-shelf discrete components, has been extensively tested through experiments conducted both in lab and real-world application scenarios. The achieved results have demonstrated the ability of RAMSES to harvest the RF energy emitted by an interrogator placed up to 10 m of distance and autonomously perform sensing, computation, and data communication. To our knowledge, this is the longest range ever reported for fully passive RFID sensors. Furthermore, for applications requiring larger operating distances, RAMSES provides also a battery-assisted passive mode yielding up to 22-m communication range. © 2013 IEEE.

This paper focuses 1 on power generation by spurious electromagnetic emissions from compact fluorescent lamps. Based on magnetic induction, a novel device consisting of a resonant loop and an RF-to-dc voltage converter is presented. Experimental tests referring to different configurations and fluorescent lamps are reported and discussed. It is demonstrated that the proposed harvester is an optimum candidate for enabling energy autonomy of a wireless sensor node.

This paper presents a wireless power link for powering implantable medical devices. The proposed link operates at 403 MHz and exploits magnetic coupling between an external resonator and an implanted resonator to wirelessly provide power to implantable devices. Experimental results for remote powering of pacemakers are reported and the compliance with safety guidelines is discussed. It is demonstrated that the proposed wireless link is able to deliver up to 1 mW with an induced 10-g average specific absorption rate lower than 1.08 W/kg. This value is significantly below the 2-W/kg recommended limit, thus proving the suitability of the proposed system to be used to energize modern pacemakers.

In this paper the feasibility of achieving a coupling-independent performance for a Wireless Power Transfer Link based on resonant inductive coupling is investigated. Theoretical and experimental results demonstrating that a coupling-independent regime can be realized by an appropriate selection of the operating frequency of a strongly-coupled synchronous WPT link are reported and discussed.

The need of traceability systems adequate for food is a matter of fact: provenance, means of processing, time of the actions, temperature during transportation, are only a few of the possible data a consumer wants to know to buy with confidence. Among the others, the wine sector is especially susceptible of applying such a system: this sector produces highly added value products and the consumers are sensible to pay more money for a better (and also better traced) product. The RFID Farm to Fork project was born with the aim of testing the ability of RFID technology to implement a complete traceability system that covers the processes from the farm to the fork. In this work, based on the joint use of RFID technology and WSN, a system for the wine traceability from vineyard to the consumer glass is described along with related electromagnetic and deployment issues. Two different wineries, selected as pilot sites, are then presented and the current deployment status reported. © 2011 University of Split.

Along with the growing of the aging population and the necessity of efficient wellness systems, there is a mounting demand for new technological solutions able to support remote and proactive healthcare. An answer to this need could be provided by the joint use of the emerging Radio Frequency Identification (RFID) technologies and advanced software choices. This paper presents a proposal for a context-aware infrastructure for ubiquitous and pervasive monitoring of heterogeneous healthcare-related scenarios, fed by RFID-based wireless sensors nodes. The software framework is based on a general purpose architecture exploiting three key implementation choices: ontology representation, multi-agent paradigm and rule-based logic. From the hardware point of view, the sensing and gathering of context-data is demanded to a new Enhanced RFID Sensor-Tag. This new device, de facto, makes possible the easy integration between RFID and generic sensors, guaranteeing flexibility and preserving the benefits in terms of simplicity of use and low cost of UHF RFID technology. The system is very efficient and versatile and its customization to new scenarios requires a very reduced effort, substantially limited to the update/extension of the ontology codification. Its effectiveness is demonstrated by reporting both customization effort and performance results obtained from validation in two different healthcare monitoring contexts.

In several application scenarios, the integration between passive RFID devices and sensors would represent a real added value, primarily in terms of cost and ease of use. In this work, two different passive RFID devices with sensing and computing capabilities are presented. The former device, named RAMSES, relies on a novel approach exploiting a new-generation I 2C-UHF RFID chip. RAMSES is able to write sensor data into the EPC code and communicate up to 5 meters of distance from a conventional RFID Class-1 Generation-2 (Gen2) reader. The latter platform, named SPARTACUS, represents the first example in literature of RFID-based device embedding sensing and actuation functionalities, distributed computation, and bidirectional communication with the Gen2 reader. Satisfactory operating range, sensing, computation, data storage, and cost-effectiveness are the main strengths making the proposed devices definitely suitable for a wide variety of applications.

The paper focuses on a near-field wireless power transmission link consisting of two magnetically coupled inductances. The case of a resonant coupling realized by adding appropriate compensating capacitances is solved. By using a network formalism, the link is modeled as a two-port network and rigorously analyzed in the case where both the input impedance and the load are specified. In particular, it is demonstrated that there is just one optimum design of the network that allows maximizing both the efficiency and the active power on the load. Closed-form design formulas for the optimum design are presented and validated by circuital simulations.

The use of Radio Frequency Identification (RFID) technology for the automatic transmission of physical parameters in wireless sensor networks paves the way to a large class of attractive applications, ranging from healthcare to automotive, diagnostic systems, robotics and many others. Nevertheless, although some RFID tags capable to transmit sensor-like information are already on the market, only a limited number of sensors, such as those for temperature or pressure measurement, can be easily miniaturized and embedded in the RFID chip. The integration of more complex sensors, in fact, appears to be complicated and extremely expensive. In this paper, a costeffective general-purpose multi-ID tag is proposed. It can be connected to generic sensors, regardless of the actual measured value, and it is capable to transmit, when interrogated by a standard RFID reader, a proper combination of ID codes that univocally codifies the sensor measured value. The functionalities of this device have been extensively validated under stressing conditions and the capability to transmit whatever kind of sensor data has been demonstrated

Over the last few years, the active and growing interest in Radiofrequency Identification (RFID) technology has stimulated a conspicuous research activity involving design and realization of passive label-type UHF RFID tags customized for specific applications. In most of the literature, presented and discussed tags are prototyped by using either rough-and-ready procedures or photolithography techniques on rigid Printed Circuit Boards. However, for several reasons, such approaches are not the most recommended, in particular they are rather time-consuming and, moreover, they give rise to low quality devices in one case, and to cumbersome and rigid tags in the other. In this work, two alternative prototyping techniques suitable for cost-effective, time-saving and high-performance built-in-lab tags are introduced and discussed. The former is based on the joint use of flexible PCBs and solid ink printers. The latter makes use of a cutting plotter to precisely shape the tag antenna on thin copper sheets. Afterwards, a selection of tags, designed and manufactured by using both traditional and alternative techniques, is rigorously characterized from the electromagnetic point of view in terms of input impedance and whole tag sensitivity by means of appropriate measurement setups. Results are then compared, thus guiding the tag designer towards the most appropriate technique on the basis of specific needs.

Radio frequency identification (RFID) technology is more and more adopted in a wide range of applicative scenarios. Nevertheless, in many applications, commercial and general-purpose solutions can be unsuitable as in the case of the tracking of small-size living animals for the behavior analysis. In such a case, the whole RFID hardware, as well as the control software, should be opportunely tailored for the particular application. In this paper, a novel RFID-based approach enabling an effective localization and tracking of small-sized laboratory animals is proposed. It is mainly based on a near-field (NF) RFID multiantenna system working in the UHF bandwidth, to be placed below the animal’s cage, and able to rigorously identify the NF RFID tags implanted in laboratory animals. Once the requirements of the reader antenna have been individuated, an antenna system composed of a matrix of specifically designed segmented loops has been prototyped. Moreover, to improve the effectiveness of the whole tracking system, a properly algorithm based on the measured received signal strength indication has been developed and integrated. It aims at removing potential minor ambiguities of the data captured by the multiantenna system. The whole animal tracking system has been then largely tested on phantom mice to verify its ability to precisely localize each subject and to reconstruct its path. Additionally, a first test performed on living mice has been presented. The achieved and discussed results demonstrate the effectiveness of the proposed approach.

In recent years, besides the advances made in canonical UHF radio-frequency identification (RFID) technology, intense research efforts are being made to design new passive augmented tags that enable RFID-based sensing. These efforts stimulate continued research aimed at providing tags with additional functionalities, besides identification and sensing. In this work, an innovative device, representing a new class of fully passive augmented UHF RFID tags, is presented. It is named SPARTACUS, an acronym for self-powered augmented RFID tag for autonomous computing and ubiquitous sensing. The device, based on an accurate electromagnetic design that exploits polarization diversity of two antennas, which perform both energy harvesting and communication, enables a full two-way proactive interaction with any standard RFID Class-1 Generation-2 reader. It conjugates identification, sensing, local computing, and actuation control, besides being compact, energy-efficient, and easy to use. This paper presents detailed designs of both RF interfaces and digital section, besides discussing system validation and performance evaluation, followed by demonstrating the significance of SPARTACUS in paving the way to new classes of applications in the Internet of Things. © 1963-2012 IEEE.

Energy saving is one of the most important issues in Wireless Sensor Network (WSN) context. Since the communication task is the most power-consuming operation, it is quite important to achieve an energy efficient communication in order to increase the lifetime of the devices through an intelligent use of the power transmission. In this context, the integration of WSN nodes with switched-beam antennas is becoming more and more appealing due to the possibility to extend sensor node lifetime by optimizing the transmitted power. In this work a switched-beam antenna for WSNs nodes in the ISM band (2.4-2.4835 GHz) is proposed. The radiating structure consists of four identical antennas, composed of an array of two L-shaped quarter-wavelength slot antenna elements arranged in a compact and symmetrical planar structure. Thanks to a properly designed switching circuit which controls the feeding of the antenna elements, one among eight possible different radiation patterns in the azimuth plane can be selected on the basis of specific needs. Simulations and experimental results, referred to a prototype realized on a FR-4 substrate, demonstrate the appropriateness of the proposed switched-beam antenna system as hardware element enabling new power saving strategies in WSN contexts.

Directional and switched-beam antennas in wireless sensor networks are becoming increasingly appealing due to the possibility to reduce transmission power and consequently extend sensor node lifetime. In this work, a reconfigurable beam-steering antenna is proposed for Wireless Sensor Network applications in the ISM band (f = 2.4-2.4835 GHz). The proposed radiating structure consists of a vertical half-wavelength dipole antenna and eight microstrip antennas composed of a rectangular two-element patch antenna array. These microstrip antennas have a directional radiation pattern in the azimuth plane with a HPBW of nearly 60 degrees. A control circuit consisting of a transmission line, RF-switches and a 4: 16 multiplexer has been designed in order to dynamically switch among nine radiation patterns, eight directional and one omnidirectional. Simulations and experimental results, referred to a low-cost realization on a FR4 substrate with a thickness of 1.6 mm, demonstrate appreciable performance.

Different approaches are commonly available for the continuous monitoring of moisture and dielectric properties of various materials. In particular Time Domain Reflectometry (TDR) is the standard method for measuring soil water content. Nevertheless, the state of the art is rather lacking in assessing specific calibration procedures allowing the accurate moisture monitoring of granular materials. To fill this gap, the adoption of TDR for such purposes is investigated. Starting from measurements on siliceous sand, an in-depth analysis is extended to various feedstuff materials (such as corn, corn flour and bran). Furthermore, the adopted methodology is fully assessed from a metrological point of view, thus confirming its suitability for the considered applications.

Two novel textile antennas are presented in this paper. The geometry of the two antennas has been shaped so to mimic the logo of two popular companies: the French clothing company LACOSTE and the American multinational corporation APPLE Inc. Two prototypes fabricated by using a conductive non-woven textile on a layer of jeans are presented. Both prototypes were optimized to work at 1.8 GHz. From experimental data excellent performance are demonstrated.

This paper presents an integrated, high-sensitivity UHF radio frequency identification (RFID) power management circuit for body sensor network applications. The circuit consists of a two-stage RF-DC Dickson's rectifier followed by an integrated five-stage DC-DC Pelliconi's charge pump driven by an ultralow start-up voltage LC oscillator. The DC-DC charge pump interposed between the RF-DC rectifier and the output load provides the RF to load isolation avoiding losses due to the diodes reverse saturation current. The RF-DC rectifier has been realized on FR4 substrate, while the charge pump and the oscillator have been realized in 180 nm complementary metal oxide semiconductor (CMOS) technology. Outdoor measurements demonstrate the ability of the power management circuit to provide 400 mV output voltage at 14 m distance from the UHF reader, in correspondence of −25 dBm input signal power. As demonstrated in the literature, such output voltage level is suitable to supply body sensor network nodes. ©2016. American Geophysical Union. All Rights Reserved.

A wearable rectenna for operation in the ultra high frequency (UHF) band is presented. The proposed device consists of a compact patch antenna and a full-wave bridge rectifier, both fabricated with textile materials. The patch antenna has been realized by using an adhesive conductive fabric on a bi-layer substrate made of pile and jeans. As for the rectifier, it is on a layer of jeans on the back-face of the antenna. Experimental data referring both to the patch antenna and to the rectenna are reported and discussed. From measurements performed with an incident power density of 14 μ/cm2, it is demonstrated that the rectenna here presented exhibits a conversion efficiency higher than 20% over the frequency range 860-918 MHz with a maximum of about 50% at 876 MHz.

This letter presents three different strategies for waking up wireless sensor network (WSN) motes via radio frequency identification (RFID). Based on our prior work on the design of augmented ultrahigh-frequency RFID tags and ultrasensitive RF energy harvesters, the proposed solutions significantly outperform state-of-art RFID wake-up radios (both broadcast based and ID based) for WSNs. In particular, improvements up to (4.2×) and (7.8×) have been achieved in terms of wake-up range and wake-up delay, respectively.

The design of fully-passive UHF RFID tags preserving cost-effectiveness, yet supplying augmented capabilities, represents an ambitious and stimulating challenge, as such devices would pave the way to a large class of applications where identification, computation, automatic cognition, and wireless sensing are required. In this work, two solutions are proposed. The former, named RAMSES, is optimized for RFID-based sensing and relies on a novel approach exploiting a new-generation I2C-UHF RFID chip. RAMSES is able to write sensor data into the EPC and communicate up to 5 m of distance from a conventional UHF RFID Class-1 Generation-2 (Gen2) reader. The latter solution, named SPARTACUS, renounces part of this long operating range in exchange for additional computing capabilities enabling an increased interaction with RFID readers. SPARTACUS represents the first example in literature of RFID device embedding sensing/actuation functionalities, distributed computation, and fully bidirectional communication with the reader. Satisfactory operating range, sensing, computation, data storage, and cost-effectiveness are the main strengths making the proposed devices definitely suitable for a wide array of novel and unconventional RFID applications. © 2014 CCIS.

Driven by user demand for new smart systems in the framework of the Internet of Things (IoT) and fueled by technological advances in Radiofrequency Identification (RFID), an increasing number of new IoT-oriented RFID-based devices has appeared in recent years in scientific literature. Some of them conjugate canonical RFID identification with extra functionalities such as sensing, reasoning, memorization, and actuation. In this way, IoT challenging applications can be developed, which distribute processing load till to the extreme nodes of the network, while lying upon the well-established RFID infrastructure. In this work, a reasoned panoramic on the potentialities in the IoT framework of augmented RFID tags is presented and classified. Two applicative scenarios are envisioned, presented and discussed, to illustrate how augmented RFID devices may support advanced IoT systems. © 2016 CCIS.

This study presents a wearable antenna for a global positioning system-global system for mobile communication (GPS-GSM)-based anti-theft tracking system to be embedded in high-cost clothing and luggage accessories (such as leather bags). To assess the feasibility of this solution, a prototype antenna was designed mimicking the shape of one of the Levi Strauss & Co.'s logos, and it was fabricated using a conductive non-woven fabric on a layer of leather. Furthermore, to cover both the GPS L1 and the GSM-1800 bands with a single radiating element, positive-intrinsic-negative (PIN) diodes were employed to reconfigure the operating frequency of the antenna. Experimental data demonstrating the feasibility of the proposed design strategy are presented and discussed.

This paper presents a wireless energy link for rechargeable implantable pulse generators for deep brain stimulation. The proposed link exploits a magnetic coupling between two compact planar resonators. From experimental results referring to a prototype working in the MedRadio band a transfer efficiency of about 10.62% is demonstrated.

This paper proposes a novel wireless link for energizing pulse generators for deep brain stimulation. The proposed link consists of two magnetically coupled planar resonators. Experimental results referring to a prototype working in the MedRadio band and using minced pork in order to take into account the presence of human tissues are reported and discussed. Results obtained this way demonstrate a transfer efficiency of about 10.62 %. The compliance with safety regulations is also verified by means of full-wave simulations.

A wireless transfer link between three magnetically coupled resonators has been considered. Two different configurations have been investigated. In one case a single transmitter and two receivers are present. In the other case two transmitters and a single receiver are employed. For each case optimal analytical solutions for the load values that maximize the power delivered to the load(s) and the efficiency have been found and validated by comparisons with circuit simulations.

We propose the realization of a compact fully-passive biotelemetry tag composed of a high-electron mobility transistor (HEMT) connected to a wireless link. The Gallium Arsenide based gateless HEMT serves both as the environmental sensing element and as the amplitude modulator of the carrier signal received by the antenna. A prototype demonstrator operating in the MHz range has been developed: it consists of an array of transistors with different gate geometries and two spiral loop resonators implementing the wireless link. More specifically, one resonator (Tag-resonator) is connected to the array of transistors, while the other one (Reader-resonator) is connected to a power generator/reader device; the wireless link uses the magnetic coupling between the two resonators. Experimental results demonstrate that the reader-resonator exhibits an intensity modulation of the resonance dip depending on the voltage applied to the HEMT gate. These results will be used as a guideline for the realization of biocompatible sub-millimeter tags operating in the Gigahertz frequency range.

This letter presents a novel X-band planar rectenna (i.e., a rectifying antenna). The proposed device consists of a slot antenna and a microstrip rectifying circuit. A realization on a low- cost FR4 substrate, using a surface-mount Schottky barrier diode (the HSMS-8202 diode by Avago Technologies) as the rectifying element, is proposed

L’invenzione proposta è un ‘harvester’ ottimizzato per la generazione di energia a partire dalle emissioni elettromagnetiche spurie delle lampade a fluorescenza. Nello specifico, il prototipo sviluppato è costituito da una spirale in rame (il trasduttore) e da un rettificatore ad onda intera (un ponte di diodi) e da un filtro passa-basso. La generazione di energia è ottenuta grazie ad un accoppiamento magnetico tra la spirale in rame e le emissioni spurie di lampade a fluorescenza comunemente utilizzate per l’illuminazione in ambiente domestico.

Il tag RFID passivo oggetto di brevetto possiede proprietà elettromagnetiche che lo distinguono dai comuni tag commerciali. Per prima cosa mantiene buone performance anche se l’oggetto da tracciare contiene liquidi e metalli. Inoltre, il tag brevettato ha un diagramma di radiazione tale da permetterne la comunicazione con le antenne-reader anche in condizioni di disallineamento. Infine, il layout dell’antenna del nuovo tag permette di minimizzare problemi di overlapping tra tag dello stesso tipo e quindi di agevolarne l’eventuale lettura multipla. Il tag brevettato è stato testato esaustivamente sullintera supply-chain del farmaco, scelta come riferimento per via delle sue criticità. Anche nelle peggiori condizioni operative quali quelle relative alla tracciabilità di sciroppi (presenza di liquidi) e bombolette spray (presenza di metalli), con presenza di disallineamento tra antenne tag e reader e con molteplici oggetti tracciati contemporaneamente, si sono ottenute percentuali di lettura con successo superiori al 99.7%. Nelle stesse condizioni operative, tutti i tag commerciali testati (circa 10 diverse tipologie tra le più performanti in commercio) hanno fatto registrare percentuali di lettura con successo inferiori all’1%. Infine, la tecnologia utilizzata per la realizzazione del tag brevettato permette di salvaguardare l aspetto dei costi. Si stima infatti che il costo per la realizzazione del tag brevettato è confrontabile con quello di un comune Tag label-type presente in commercio. Le sue dimensioni particolarmente ridotte, inoltre, ne permettono l’agevole integrazione con gli oggetti da tracciare.