With the emerging developments in millimeter-wave/5G technologies, the potential for wireless Internet of things devices to achieve widespread sensing, precise localization, and high data-rate communication systems becomes increasingly viable. The surge in interest surrounding virtual reality (VR) and augmented reality (AR) technologies is attributed to the vast array of applications they enable, ranging from surgical training to motion capture and daily interactions in VR spaces. To further elevate the user experience, and real-time and accurate orientation detection of the user, the authors proposes the utilization of a frequency-modulated continuous-wave (FMCW) radar system coupled with an ultra-low-power, sticker-like millimeter-wave identification (mmID). The mmID features four backscattering elements, multiplexed in amplitude, frequency, and spatial domains. This design utilizes the training of a supervised learning classification convolutional neural network, enabling accurate real-time three-axis orientation detection of the user. The proposed orientation detection system exhibits exceptional performance, achieving a noteworthy accuracy of 90.58% over three axes at a distance of 8 m. This high accuracy underscores the precision of the orientation detection system, particularly tailored for medium-range VR/AR applications. The integration of the FMCW-based mmID system with machine learning proves to be a promising advancement, contributing to the seamless and immersive interaction within virtual and augmented environments.

This communication designs and investigates a twin-port microstrip antenna loaded with a metasurface (MS). The proposed MS works in two ways: (i) artificial ground plane for radiator and (ii) as an ideal absorber of normal incoming waves at the same time. A stair shaped slot is loaded on rectangular patch for creating circularly polarized wave in between 835–894 MHz. Antenna port slots oriented in a mirror manner increase isolation by 25 dB. To act as a validation tool, the suggested antenna was built and its executions in individually operating modes evaluated by statistical and experimental analysis. It is shown that combining the patch and absorber results in a well-matched antenna in between 710–980 MHz with improved gain (more than 3.0 dBi). The proposed antenna design effectively used for UHF (Ultra High Frequency)radio-frequency identification (RFID) applications, which is due to its ability to mitigate multipath reflection issues and incorrectRFID reading.

In this article, an innovative design of a broadband circularly polarized compact planar antenna for RFID (radio frequency identification) receivers is presented. The suggested structure used the concept of slots loaded parasitic element printed underneath a coplanar waveguide-fed radiator to achieve the circularly polarized (CP) radiation and size reduction. A parasitic element loaded with F-slot and L-slot, and a window-type slotted ground plane was used to achieve resonance at 2.45 GHz with right-handed circularly polarized radiation for RFID handheld reader application. Experimental results confirmed that the designed antenna of size 16.5 × 14.8 × 1.6 mm3 attained a −10 dB impedance bandwidth of 15.8% (from 2.330 to 2.716 GHz) and 3 dB AR bandwidth of 3.43% (from 2.410 to 2.494 GHz). An axial ratio of 0.43 dB was achieved in the boresight of the antenna at the 2.45 GHz RFID band. The concept of electric field distribution on the antenna was used to elaborate the excitation of CP radiation in the antenna.

In order to encrypt/encode data based on the magnitude level of the radar cross-section (RCS), we propose an approach with a precise estimation considering the resonant characteristics of a multipatch backscatter-based chipless radio frequency identification (RFID) dedicated for chipless tags depolarization. The working principle is based on the polarization mismatch between the tag and the reader antenna to control the magnitude of the backscatter, which allows a reliable detection in real environments. We introduce in this paper a new 4-bit chipless RFID tag with an enhanced RCS, based on a triangular patch antenna with multiple resonators. Additionally, we propose an ultra-wideband impulse radar (UWB-IR)-based reader that interrogates the chipless tag with a UWB pulse, and the received backscatter was studied in both time- and frequency-domains. The antenna was operating from 4.7 to 6.1 GHz, a band allocated for RFID systems. The obtained experimental measurement results in the environment of anechoic chamber were exceptionally relevant to validate the simulation results.

New small unmanned air vehicles designated as micro air vehicles (MAVs) are increasingly attractive for research, environmental observation, and commercial purposes. As described herein, the feasibility of a system for wireless power transmission via microwaves for MAVs was investigated. For its light weight and flexibility, a textile-based rectenna was proposed for microwave wireless power transmission of MAVs. To investigate bending effects on radiation performance, a microstrip patch antenna with a 5.8 GHz left-hand circular polarization was developed on a textile substrate. The antenna return loss, 20 dB, increased slightly with the antenna bending angle. An axial ratio <3 dB was maintained when the antenna bend angle was <30°. A rectification circuit was formed on the back side felt with sandwiched copper foil as a ground plate. Its weight per unit area was 0.08 g/m2, with maximum rectification efficiency of 58% with 100 Ω load at 63 mW input power. The average and maximum total transmission efficiency using the 5.8 GHz multiple rectenna with a 2.45 GHz retrodirective system were, respectively, 0.44 and 0.60%. The possibility and feasibility of microwave power transmission system using the textile-based rectenna were evaluated.

Free-range laying hen systems are increasing within Australia. The pullets for these systems are typically reared indoors before being provided first range access around 21 to 26 weeks of age. Thus, the rearing and laying environments are disparate and hens may not adapt well to free-range housing. In this study, we reared 290 Hy-Line® Brown day-old chicks divided into two rooms each with feed, water and litter. In the enriched room, multiple structural, manipulable, visual and auditory stimuli were also provided from 4 to 21 days, the non-enriched room had no additional objects or stimuli. Pullets were transferred to the laying facility at 12 weeks of age and divided into six pens (three enriched-reared, three non-enriched-reared) with identical indoor resources and outdoor range area. All birds were first provided range access at 21 weeks of age. Video observations of natural disturbance behaviours on the range at 22 to 23 and 33 to 34 weeks of age showed no differences in frequency of disturbance occurrences between treatment groups (P=0.09) but a decrease in disturbance occurrences over time (P<0.0001). Radio-frequency identification tracking of individually tagged birds from 21 to 37 weeks of age showed enriched birds on average, spent less time on the range each day (P<0.04) but with a higher number of range visits than non-enriched birds from 21 to 24 weeks of age (P=0.01). Enriched birds accessed the range on more days (P=0.03) but over time, most birds in both treatment groups accessed the range daily. Basic external health scoring showed minimal differences between treatment groups with most birds in visibly good condition. At 38 weeks of age all birds were locked inside for 2 days and from 40 to 42 weeks of age the outdoor range was reduced to 20% of its original size to simulate stressful events. The eggs from non-enriched birds had higher corticosterone concentrations following lock-in and 2 weeks following range reduction compared with the concentrations within eggs from enriched birds (P<0.0001). Correspondingly, the enriched hens showing a greater increase in the number of visits following range area reduction compared to non-enriched hens (P=0.02). Only one rearing room per treatment was used but these preliminary data indicate 3 weeks of early enrichment had some long-term effects on hen ranging behaviour and enhanced hen’s adaptability to environmental stressors.

A meandered-dual-antenna structure is proposed for UHF radiofrequency identification (RFID) tag. It is composed of two independent antennas printed on the one side of the substrate board. One of the antennas is exclusively used for receiving and harvesting sufficient energy to the tag chip having the complex conjugate impedance of the receiving antenna. The other is for backscatter to enhance maximum differential radar cross-section with purely real input impedance, to enhancement the read range. The receiving antenna is formed by a rectangular loop and a parasitic meandered line. The rectangular loop is used as a feeding element for the meandered line. The backscattering antenna is made using a meandered dipole along with a thin rectangular strip. The input impedance of the receiving antenna is designed to be conjugate matched to the chip impedance (13.5-j110 Ω), whereas the input impedance of backscattering antenna alternatively switched to open and short circuit for modulating the backscattered field. The input impedance of receiving and backscattering antennas is measured using differential probe technique. The simulated and measured results are found in good agreement. It is also demonstrated that the read range of UHF RFID system increased considerably by using the dual-antenna structure.

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 paper proposes a Radio Frequency Identification (RFID)/ in-vehicle sensors fusion strategy for vehicle positioning in completely Global Positioning System (GPS)-denied environments such as tunnels. The strategy employs a two-step approach, namely, the calculation of the distances between the RFID tags and the reader, and then the global fusion estimation of vehicle position. First, a Least Square Support Vector Machine (LSSVM) algorithm is developed to obtain distance. Next a novel Federated Unscented Kalman Filter (FUKF) is designed to realise the global fusion. The decentralised federated filter is adopted to combine the data from RFID and in-vehicle sensors, and the UKF is employed to design a local filter since it has better ability to deal with a nonlinear problem than an Extended Kalman Filter (EKF). Due to the optimised layout of RFID tags and the application of the decentralised filter, the number of tags is reduced. Finally, the feasibility and effectiveness of the proposed strategy are evaluated through experiments.

Power-optimized waveforms (POWs) are the enabling technology for realizing an internet-of-things (IoTs). An IoT will require billions or trillions of sensors, which must rely on passive, backscatter communication to facilitate the wireless transfer of information. Passive, backscatter sensors are uniquely suited for an IoT because of their ease of installation, low-cost, and lack of potentially toxic batteries. POW's primary benefit is that they can greatly improve the energy-harvesting efficiency of passive sensors, which increases their range and reliability. An overview of POWs is presented followed by measured results validated by a theoretical model and computer simulations. These measured results conducted at 5.8 GHz demonstrate the highest reported efficiency of a low-power, microwave energy-harvesting circuit of 26.3% at an input power of −10.2 dBm when using an excitation signal with a peak-to-average-power ratio of 12.

This work proposes a chipless radio frequency identification approach based on the working principle of the harmonic radar. A frequency multiplication stage is performed by a non-linearity (i.e. a Shottky diode) on the tag in order for the tag answer to be insulated from the interrogation signal, thus avoiding the need for clutter cancellation techniques. Firstly, the performance of a simple one-bit harmonic tag relying on a low-power frequency doubler is analyzed and then a novel crack sensor, implemented by adding a disposable band-stop filter, is presented. Both solutions demonstrate tag-to-reader operational distances beyond 1 m. The characterizing blocks (namely the frequency doubler and the filter) are fabricated on cellulose substrates (i.e. regular photographic paper), thus being conformal to their implementation for applications in the new paradigm of Internet of Things.

This paper discusses the electromagnetic (EM) signature of Arabic alphabets that can be considered as standards particles to form chipless tags. Normalized Arial font is suited as example but the method can be applied for any other font. The letters are realized by metallic strips or better, by conductive ink. All the 28 letters have been simulated and their EM signatures for both field polarizations are extracted. It is demonstrated that combining vertical and horizontal responses allow the identification of letters without ambiguity. Moreover, the case of letter with punctuation (one to three points) is considered in more details. Indeed, we propose to modify very slightly these letters by connecting the points to the body of the letters. This connection is made by a unique straight and very thin strip. Under this modification these letters exhibit more exploitable signatures. Finally, a lookup table for identification of the 28 letters is carried out.

This paper presents the design procedure of two ultra-high-frequency radio frequency identification reader antennas used in searching tagged items. They consist of microstrip arrays with alternating orthogonal dipoles, which are fed in series by a pair of microstrip lines. The dipoles are designed properly to provide the required bandwidth. The inter-element distance is adjusted to the center frequency, where the elements provide in-phase excitation and create two orthogonal electric-field components that give beams with direction diversity. Simulated results show that the return loss bandwidth (RL > 13 dB) of the first antenna design covers the required frequency band of ETSI (865–868 MHz) standard. In addition, simulated and measured results of the second antenna design indicate that the return loss bandwidth covers both the frequency bands of european telecommunications standards institute (ETSI) and federal communications commission (FCC) (865–928 MHz) standards. Regarding the coverage volume in the vicinity of the antenna, it was deduced that both antennas can read tagged items in a semi-cylindrical volume that extends to a radius of more than 50 cm. Finally, a case study of reading tagged books in front of a library cabinet with six shelves has been presented.

In this paper a novel compact multi-band printed coplanar waveguide (CPW)-feed antenna for wireless local area network (WLAN)/WiMAX/RFID applications is proposed. The proposed antenna is composed of a multi-triangular structure as metal ground plane and the radiation element with four different branches, both of the structures are printed on the same side of a substrate and the antenna is fed by a CPW. By carefully tuning the locations and the sizes of these four branches, the antenna can yield three different resonating frequencies to cover the desired bands for WLAN/WiMAX/RFID applications. The simulated and measured results demonstrate that the proposed antenna has the impedance bandwidth (for return loss less than −10 dB) of 700 MHz (2.2−2.9 GHz), 540 MHz (3.16–3.7 GHz), and 850 MHz (5.05–5.9 GHz), respectively, which can cover the WLAN 2.4/5.8 GHz bands, the WiMAX 2.5/3.5 GHz bands, and the RFID 2.45/5.8 GHz bands.

Introduction: In mass-casualty situations, communications and information management to improve situational awareness is a major challenge for responders. In this study, the feasibility of a prototype system that utilizes commercially available, low-cost components, including Radio Frequency Identification (RFID) and mobile phone technology, was tested in two simulated mass-casualty incidents.

Methods: The feasibility and the direct benefits of the system were evaluated in two simulated mass-casualty situations: one in Finland involving a passenger ship accident resulting in multiple drowning/hypothermia patients, and another at a major airport in Sweden using an aircraft crash scenario. Both simulations involved multiple agencies and functioned as test settings for comparing the disaster management’s situational awareness with and without using the RFID-based system. Triage documentation was done using both an RFID-based system, which automatically sent the data to the Medical Command, and a traditional method using paper triage tags. The situational awareness was measured by comparing the availability of up-to date information at different points in the care chain using both systems.

Results: Information regarding the numbers and status or triage classification of the casualties was available approximately one hour earlier using the RFID system compared to the data obtained using the traditional method.

Conclusions: The tested prototype system was quick, stable, and easy to use, and proved to work seamlessly even in harsh field conditions. It surpassed the paper-based system in all respects except simplicity of use. It also improved the general view of the mass-casualty situations, and enhanced medical emergency readiness in a multi-organizational medical setting. The tested technology is feasible in a mass-casualty incident; further development and testing should take place.

This paper describes existing and new criteria for comparison and optimization of non-linear power amplifiers such as RF or microwave transmitters. In addition to intermodulation, receiver noise, and losses in the transmission system, the proposed new criteria take into account efficiency or consumed power. This results in the global optimization of a combined signal-to-noise-plus-intermodulation ratio as a function of saturated or nominal power but also consumed or dissipated power. Saturated power is limited by available technology. Consumed power and dissipated power are some of the main constraints in telecommunication satellite payloads, mobile phone handsets, and RFID (Radio Frequency IDentification). Another constraint comes from the limited size of antennas, which limits the system equivalent isotropic radiated power and gain-to-temperature ratio. With the proposed criteria the designer will be able to compare different amplifier technologies and to optimize the design and operating point of each stage of a multistage amplifier or a linearizer for a given amplifier. Interference from same or other systems is also introduced in the optimization through the use of signal-to-noise-plus-IM-plus-interference ratio criteria.

This paper deals with a robust RFSID (Radio Frequency Self IDentification) system for road-to-car communications. The RFSID-based system operates in Ku-band and consists of a fixed transmitter, located at the road side, and of a receiver unit placed on the moving target, i.e. a car in its first proposed application. A slotted waveguide antenna array is used to illuminate the moving object at the desired position, whereas a four-patch array antenna is adopted at the receiver side. Both the antennas have been designed using numerical simulations based on a Finite Difference Time Domain (FDTD) algorithm. When the moving object crosses the antenna beam a triggering pulse is generated by the receiver; such a pulse can be used to reset or update the electronics aboard the vehicle and to log specific information coming from location-based systems (LBSs), into the car equipments. A digital transmission of gold sequences and a post-processing unit have been exploited so far to increase the robustness and the accuracy of the system. At this stage of the development the system benefit of extensive field tests, being adopted for some years by many top Formula 1 racing teams as a lap trigger system, used to reset the on-board electronics when the car crosses either the finishing line and peculiar path reference points. The temporal accuracy exhibited is better than 1 ms with a coverage of about 90 m.