It is well established that replacing the traditional continuous-wave signals with pulsed-wave signals improves the performance of passive UHF (Ultra High Frequency) RFID (Radio Frequency Identification) systems in terms of wireless power transfer. However, the impact of this change on the performance of these systems in terms of information transmission has been little analyzed. Based on the maximum ratio combining principle, this paper describes the optimal multi-carrier receiver processing that maximizes the information performance of passive UHF RFID systems in pulsed-wave mode. In addition to the theoretical description of the processing, numerical simulations are performed to test the estimators required for the proposed combination process. Finally, experimental measurements are performed to confirm the feasibility of the proposed processing with real data and verify the performance stated in the theory.

It is well established that replacing the traditional continuous-wave signals with pulsed-wave signals improves the performance of passive UHF (Ultra High Frequency) RFID (Radio Frequency Identification) systems in terms of wireless energy transfer. However, the impact of this change on the performance of these systems in terms of information transmission has been little analysed. This paper describes the optimal multi-carrier processing to be applied at the receiver end that maximizes the information performance of pulsed-wave passive UHF RFID systems. It is shown that in the realistic case of unknown and frequency-diverse propagation channels and tags, the pulsedwave mode guarantees a performance equal to the average over the frequency band of interest of the performances obtained in the continuous-wave mode.

The concept of ambient backscatter communication enables passive devices (or tags) to communicate using a nondedicated radio-frequency source present in their environment. This technique is highly attractive, since it requires no specific energy consumption or maintenance. Although experimentally demonstrated, its widespread adoption in commercial devices remains highly constrained by limited distances, low data rates and high sensitivity to complex propagation environments. This article presents a flexible, mixed modeling and simulation environment (with several modeling levels: electromagnetic, circuit, component, signal, system) that enables in-depth study of the performance of the radio link between two tags exploiting this principle. For the purposes of illustration, the backscattered signal is modelled by a two-level ASK (Amplitude Shift Keying) modulated signal, which is obtained by load modulation considering the electromagnetic coupling between the two tags. The performance of the radio link is evaluated through the BER (Bit Error Rate) as a function of the signal-to-noise ratio. Two types of receivers, coherent and non-coherent, are compared, and several communication scenarios are also considered. Simulation results are validated by the associated theoretical study.

This paper aims to demonstrate that a network of tags can be 'controlled' (or configured) to improve communication between two radio nodes, using the same principle as for reconfigurable intelligent surfaces (RIS). RIS enables dynamic, targeted control of radio signals between a transmitter and a receiver, considering the propagation environment to optimize the radio link. However, RIS have to be specially deployed, and face the problem of remote control and energy supply. Assuming that future generations of passive RFID tags will incorporate the ability to switch between different load impedances in a reader-controlled way, the concept proposed here is to use tag networks already present in the environment as RIS. In addition to demonstrating this concept through several scenarios, the aim here is to introduce and compare different strategies for optimizing the choice of load impedances. The proposed analysis is also based on two modeling approaches: the first, based on the Friis equation, provides a clear illustration of the concept and its issues; the second, more general and realistic, is based on an N-port electrical equivalent model, and enables us to consider tag networks with more complex geometries, with no constraints on inter-tag distances. The results obtained are promising and demonstrate the potential of such an approach.

This paper presents the design of a high-performance dual-band antenna for industrial, scientific, and medical (ISM) band applications. The proposed prototype consists of a low-cost patch antenna, 40 mm × 24 mm in size (i.e., 0.36λ0 × 0.19λ0, with λ0 the wavelength corresponding to the low frequency), with a relatively wideband for both operational bands (up to 140 MHz at 2.45 GHz and 510 MHz at 5.8 GHz), and a radiation efficiency of over 90%. The antenna has a quasi-omnidirectional radiation pattern with gains of 2.41 dBi and 5.22 dBi at 2.45 GHz and 5.8 GHz, respectively. The design methodology is detailed and illustrated by simulation results showing the optimization steps and the characteristics associated with the antenna. Experimental results based on a fabricated prototype are presented and compared with simulation results from the design stage. Finally, the proposed antenna prototype is also compared with similar antennas available in the literature.

ABSTRACT This paper presents the design of a high‐performance rectifier for radiofrequency energy harvesting (RF‐EH) system. The proposed prototype operates in the two frequency bands, 2.45 and 5.8 GHz (part of the radio spectrum reserved internationally for industrial, scientific, and medical [ISM] purposes), which are widely present in the ambient environment, and enables energy to be recovered at low power levels to power loads of widely varying impedances. The designed rectifier is manufactured with dimensions of 0.31 × 0.17, with the wavelength corresponding to the 2.45 GHz frequency. The rectifier is dual‐band with a single series topology and good performance in terms of conversion efficiency at very low power levels (18% at −20 dBm at 2.45 GHz and 14% at −10 dBm at 5.8 GHz). The design methodology is detailed, and experimental results based on the prototype are presented and compared with the literature.

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This paper describes an effective method for improving the detection of UHF RFID (Ultra High Frequency Radio Frequency Identification) tags in a restricted area. The so-called zoning technique is a recurring problem in practical RFID applications: it consists in detecting within an environment with multiple tags that are exclusively present in the zone of interest. The proposed method is based on the concept of Nth harmonic, a new paradigm that involves utilizing the harmonic signals backscattered by tags. Such a method is coupled with a machine learning technique. Experimental results show the importance of harmonic features for better tags zoning. Using a four-layer CNN classifier, we can achieve 99% prediction accuracy by leaving a keep-out distance of 0.5 m between two zones, using the harmonic RSSI (Received Signal Strength Indicator) sum feature, and 94.7% by using the best feature at f0, which is the RSSI max, achieving around 5 times less prediction errors. Furthermore, combining the harmonic and fundamental features leverage the prediction accuracy to 99.8%.

Radio frequency identification (RFID) technology, and in particular the passive UHF (ultra-high frequencies) standard, is developing strongly with the emergence of cognitive sensor networks and especially the Internet-of-Things. A significant indicator of this evolution is that tags are increasingly equipped with new capabilities: in addition to the identification functionality, there are, for example, those of sensor or actuator. In this context, the energy requirement at the tag level, known as augmented tag, is clearly increasing. Consequently, on the one hand, reading distances can be limited (the energy received is shared between the different components of the augmented tag) and on the other hand, to overcome the problem, semi-passive solutions (on-board battery to power the active electronic circuits) are proposed at the expense of the decisive advantage of the passive nature of the tags. It is therefore necessary to find alternative solutions to optimize the energy transfer between the reader and the tags. The concept proposed here is to target a particular tag, the one being queried, and to exploit the tags in its vicinity as reflectors in order to converge a maximum of power transmitted by the reader on the “target” tag. The paper uses an adapted mathematical formalism to evaluate the total power that can be received by a target tag as a function of the tags in its neighborhood: the impact of their relative position and of the load impedance of the reflector tags is analyzed and illustrated by simulations.

This paper presents the design of an ultra high-frequency (UHF) radio frequency identification (RFID) sensor tag integrated into a textile yarn and manufactured using the E-Thread® technology. The temperature detection concept is based on the modification of the impedance matching between RFID tag’s antenna and the chip. This modification is created by the change in the resistance of a thermistor integrated within the tag system due to a temperature variation. Moreover, in order to obtain an environment independent detection, a differential approach is proposed that avoids the use of a pre-calibration phase by the use of a reference tag. Experimental characterization demonstrates the RFID sensor’s potential of detecting a temperature variation or a temperature threshold between 25 and 70 °C through the variation of the transmitted differential activation power.

In this paper, a novel methodology to design Ultra High Frequency Radio-Frequency IDentification (UHF RFID) tag antennas with Barcode layout is proposed with the challenging goal of "fusing" both technologies in a single device. Specifically, after a brief recall of the well-known barcode standard, a procedure to design meandered barcode-shaped UHF RFID tags is introduced and discussed leveraging on electromagnetic evidence. The main steps of the proposed method are described by highlighting the constraints inherited by both the adopted technologies, as well as the useful opportunities to automatise the entire antenna design process after a preliminary simulation campaign through a full-wave simulator. Different RFID-Barcode tag antennas are designed, manufactured, and characterised in terms of maximum reading range and tag sensitivity. Obtained results demonstrate the validity of the proposed approach.

Despite its first applications in the 1940s and 1950s, RF identification (RFID) technology only really developed starting in the early 2000s with the development of the international Electronic Product Code standard. As its name indicates, the original function of RFID was the identification of objects, animals, and people via a tag that contains a unique identifier. However, RFID is now being given new capabilities, such as integrated sensors or actuators, additional memory, and better security, which implies that its potential fields of application will keep growing, especially with the rise of the Internet of Things. In its passive version, which is the original RFID, the tag is a passive electronic component, mainly composed of an antenna and an integrated circuit (called an RFID chip ), that is remotely powered and that emits its identifier using the principle of modulated backscattered communication. The remote powering and backscattering require a reader in the vicinity of the tag that acts as both a radio transmitter and a receiver and as an external RF power source.

The omnipresence of connected objects leads to the quasi-permanent presence of electromagnetic waves from different sources in our environment. This article presents a new electromagnetic energy harvesting device, rectenna type, which offers the advantage of being versatile. Indeed, the proposed prototype is compatible with three frequency bands of radio standards widely deployed today (UHF RFID, GSM-1800, and UMTS-2100), and its performances remain good for low to very low ambient power levels as well as for different loads depending on the targeted application. The proposed solution is based on a tri-band antenna with very good efficiency and a bandwidth of at least 80 MHz for each of the operating frequencies. Moreover, the associated rectifier circuit is also tri-band and offers good performance in terms of RF-to-DC conversion efficiency for input levels varying in a rather wide range of power levels. The study is based on a design phase by simulation until the realization of prototypes and their experimental characterization. The designed rectenna is compared with solutions found in the literature.

RFID (radio frequency identification) technology appeared nearly 70 years ago. Deployed more widely only from the early 2000s, it is now booming and its development is still accelerating. As its name indicates, its original function was the identification (of objects, animals, people) and its applications were then essentially aimed at traceability, access control and logistics. If this type of use is still relevant today with more and more new application contexts and more and more efficient RFID tags, RFID has also evolved by integrating new capabilities. These new tags, known as augmented tags, include an information capture function. With the explosion of connected objects and the emergence of the Internet of Things (IoT), this old technology that is RFID still has a promising future and will probably be more and more present in our private and professional environments in all fields: logistics, industry, agriculture, building, health and even space.

In the context of the UHF (Ultra High Frequency) passive RFID (Radio Frequency Identification) technology, recent works have proposed a new paradigm demonstrating the possibility to perform short distance tag to tag (T2T) communications. This paper presents a study that focuses on the performance evaluation of T2T systems. Without loss of generality as to the methodology followed, dipole antennas are considered here (assumed ideal in the theoretical part, then printed for the rest of the study). The results obtained show that the modulation depth, which can be considered as an evaluation metric for the T2T systems, is strongly impacted by three main parameters: the switching impedances (here chosen as short-circuit and open-circuit); the geometrical configuration constituted by the two tag antennas forming the T2T system; and also, the position of the external source on which the backscatter communication relies. As the modulation depth is very sensitive to these three parameters, which are more or less directly related, it is very difficult to predict the communication quality for a given configuration. For example, when the two tags are in parallel and the source is symmetrically positioned, the modulation depth shows a decreasing trend by oscillating when the distance between the tags increases from $0.1~\lambda $ to $1~\lambda $ ( $\lambda $ being the wavelength): with values going from 70% to less than 5%. As a consequence, from a very complete set of scenarios considered, the presented study helps to illustrate and explain the interactions of these parameters and their impact on the modulation depth. And at the same time, the paper provides guidelines for defining the specifications of such a system based on quantified results. The set is completed by introducing the BER (Bit Error Rate) as an evaluation metric by considering then a more complete T2T system (for instance listener tag including a non-coherent envelope detector).

A low-loss vertical transition between microstrip line and air-filled substrate integrated waveguide (AFSIW) at Ka-band is proposed. The objective is to be able to connect active components based on microstrip technology with passive components based on AFSIW technology. The coupling between the quasi-TEM mode of the microstrip line and the TE 10 mode of the AFSIW guide is carried out by a slot and a copper line placed on one layer of the substrate. To obtain reliable measurements, a back-to-back transition has been designed and fabricated. The measured results obtained show that over a frequency range of 27.5 GHz to 29.8 GHz the proposed transition has a reflection coefficient of between −10 dB and −15 dB and insertion losses between 0.78 dB and 1.45 dB.