High Read Range Research Articles

Integration of RFID tag in additive manufactured parts

This paper discusses the integration of on-metal tags in additively manufactured Ti-6Al-4V geometries. The manufactured components are to be equipped with information and read out due to aircraft maintenance work. Due to the complex installation and the mostly insufficient accessibility of the component in the installed state in the aircraft, a high read range and readability is mandatory. The integration involves ultra-high-frequency tags, which should promise a long range. The readability of the tags was therefore investigated in different open geometries. Here, some of the integrated tags were readable. In addition, tags were completely embedded in order to understand the effects in the component. The focus here was on the effects in the embedding chamber of the tag. Therefore, the fully embedded tags were cut open and examined. Some tags were readable, others were destroyed during the process. This was due, among other things, to the very hot environment of the process, as this depends highly on the actual permitted operating temperature of the tags. In addition, powder residues and adhesions were noted. These aspects are crucial for subsequent research involving the integration of tags.

Improved UHF-RFID Tag Design and Middleware Implementation for Effective Site Management and Access Control at Construction Site

Effective site management and access control are useful aspects to implement at the construction industry. In particular, monitoring personnel, construction materials, and equipment is considered predominant elements at these sites as they constitute more than half of the total project cost. Thus, to provide accurate and timely information of man/materials, UHF-RFID technology integrated with Middleware acts as a pioneering solution for real-time data monitoring. This work develops a new approach to implement the Automatic Identification and Data Capture (AIDC) solution through Middleware integrated with the UHF-RFID system. To design a UHF RFID tag, we propose a new platform tolerant Artificial Magnetic Surface (AMC) meta surface integrated tag for tracking man/material at the construction site. The novelties of the proposed tag lie in its improved radiation characteristics and stable high read range performance on different items. The designed tag was fabricated and tested experimentally in a real outdoor scenario by placing it on different items such as personnel and metal objects. At the same time, we developed UHF-RFID system integrated web application through Middleware to provide digital worksite visibility for access control and on/off-site management. Thus, the developed system will act as an automated tool to remotely fetch the information from different working zones at the construction site.

A Small All-Corners-Truncated Circularly Polarized Microstrip Patch Antenna on Textile Substrate for Wearable Passive UHF RFID Tags

We present a wearable passive UHF RFID tag based on a circularly polarized (CP) patch antenna on a textile substrate. The antenna miniaturization is based on applying a combination of the cross- and L-shaped slots in the radiator. In conjunction, the right-hand circular polarization is achieved by asymmetrically truncating all four corners of the square-shaped radiator. Despite using a regular low-permittivity textile as the antenna substrate, we downsized the antenna to a 5 cm × 5 cm footprint with the thickness of 4 mm, which is equal to 0.1525 λ × 0.1525 λ × 0.0091 λ, where λ is the free space wavelength at 915 MHz. In the numerical modeling and optimization of the antenna, we used a simplified cuboid-shaped and anatomical human body models. In addition to simulated conventional antenna performance indicators, we introduce spatial coverage as a new parameter for assessing the detection reliability of UHF RFID tags. Finally, we measured a manufactured tag worn in four different configurations on the body. The measured axial ratio value was approximately 2 dB in all cases and the tag provided a high attainable read range of around 5.8 meters for a right-hand CP reader emitting 3.28 W EIRP.

Experimentally validated smart card ultra‐high frequency tag antenna for free space and near body scenarios

This investigation primarily promotes a ultra-high frequency radiofrequency identification (RFID) tag antenna for complex environment applications of smart card in free space and near body scenarios. It also considers other high dielectric materials such as water and metallic objects. A dual dipole antenna with T-match structure is chosen due to the advantage of providing high resilience towards change in impedance of high dielectrics, and to ensure the reception of maximum signals at the blind spots of the antenna. The proposed geometry facilitates placement of other off-the-shelf high and low-frequency antennas on the card, enabling more features, higher performance, and minimum field interaction between different frequencies. A presented RLC equivalent circuit model estimates the impact of body layers on antenna impedance. A high read range of 7.7 m in free space, 5.2 m near body and 2.8 m at the blind spots is obtained. The novelty is shown by testing the antenna near metals and water, achieving high read range without any design modifications. The proposed tag aims to provide new RFID applications that demand small size, less volume, low cost and multifunctionality over various constraints while showing good agreement with sensitivity, impedance matching and the read range.

Low-Profile Vertical Polarized Slotted Antenna for On-Road RFID-Enabled Intelligent Parking

A low-profile vertical polarized antenna is presented for radio frequency identification (RFID)-enabled intelligent parking system applications. In order to reduce the crosstalk between antennas and false detection of vehicles in the parking zone, a bidirectional antenna with low vertical obstacle is required by industry. To that end, a low-profile cavity-excited magnetic dipole-based antenna with vertical polarization is designed. Two vertical sides of the antenna are kept open for the easy access of the reader and powering components. In order to increase the polarization purity along the intended sides, a rectangular truncated ground plane is proved to be beneficial compared to a typical square shaped one. The overall structure of the on-road antenna over the ground plane is around $0.2\times 0.55\times 0.06\,\,\lambda _{0}^{3}$ ( $\lambda _{0}$ is the free space wavelength of the center frequency). The design process and operating principle of the antenna are described in detail along with the effects of different parameters. The antenna is prototyped and measured. The antenna attains high reflection coefficient of −20 dB over 912–930 GHz covering the intended Australian ultrahigh-frequency (UHF) RFID band. The antenna demonstrates bidirectional radiation patterns having a maximum gain of 5 dBi over the required band with −20 dBi cross-polarization level. On-road measurements of the prototype show that the 3 dB beamwidth extends to ±90° elevation angles, which provides high read range while the tags embedded in the vehicle’s license plate are in low elevation. The antenna has a rugged structure to sustain more than 10 years in regular road and traffic conditions. By meeting all the requirements, it has been proved to be an effective part of the on-road RFID-enabled intelligent parking system.

Compact meandered RFID tag antenna with high read range for UHF band applications

In this work, a compact, long read range, and an efficient spiral loop structure coupled tag antenna is proposed for UHF-RFID applications. Meandered line element is inductively coupled to spiral loop for matching its input impedance to Higgs-4 chip. Equivalent circuit of antenna is extracted to analyze its working mechanism in the operating band. Experimental characterization validates the performance of proposed tag antenna in free space and on cardboard sheet in terms of read range, tag sensitivity, and differential radar cross section with an EIRP of 3.28 W. The measured radiation pattern of the tag is found to be omnidirectional in H plane and figure of eight in E plane. The tag's read range is measured on objects like fiber, wood, plastic, and glass in outdoor scenario to study its environment tolerance. The tag antenna has volumetric size of 1736 mm3 and read range of 13.6 m in US RFID band.

Self-Tuning RFID Tag: A New Approach for Temperature Sensing

This paper aims to present a further exploration on a new concept regarding the operation of an ultrahigh frequency (UHF) radio frequency identification (RFID) sensor tag. Exploiting the antenna of a UHF RFID tag as a temperature transducer and a UHF RFID chip with self-tuning capabilities as the means of communication, a UHF RFID tag can operate as a very low-power sensor with high read range and small size. The antenna of the tag is taking advantage of the intrinsic characteristics of the used substrate to vary its overall complex impedance according to temperature. These changes of the impedance of the antenna are leading the self-tuning circuit of the used RFID chip to self-tune and based on the value it acquires an estimation of the sensed temperature can be made. This paper also reports a design and a set of measurements of a UHF RFID tag transformed to act as a temperature sensor. This concept is further explored for the assessment of the contribution of each of the constituents of the UHF RFID tag, i.e., antenna and UHF RFID chip, to the sensing procedure. This paper is accompanied by the simulation of a designed 3-D model of the UHF RFID sensor tag and by sets of measurement of the impedances of the UHF RFID chip and of the antenna.

Novel approach to determine the influence of pig and cattle ears on the performance of passive UHF-RFID ear tags

The potential of passive ultra-high frequency radio frequency identification (UHF-RFID) as an electronic identification technology for precision livestock farming applications has been evaluated in different projects. Despite very promising advantages, such as a high read range and simultaneous identification of animals, the application of UHF transponders in ear tags still struggles with the strong influence that body tissue in the vicinity of the transponders has on the reading performance of the system. A detailed and precise investigation of the influence of ears on the transponder ear tags to support transponder development is hardly possible in on-farm tests with animals. Thus, the aim of this study was to develop an approach to measure the influence of pig and cattle ears on the received signal strength indicator (RSSI) and read range of UHF transponder ear tags on a test bench. In a second step, replacement of cattle and pig ears in the experiments with tissue models was tested to enhance the repeatability and comparability of results. Three sets of tests were performed with three different types of UHF transponders (1) to compare the influence on the read range and RSSI of the transponders at the front and back of pig and cattle ears, (2) to determine the repeatability of measurements with ears, and (3) to compare the influence of pig ears with that of two tissue models. Results showed significant differences between the front and back side of the ears for pig ears with better results at the back. The results for cattle ears were heterogeneous. The repeatability of measurements was low in all variants (front and back of pig and cattle ears) with repeatability coefficients of up to 10dBm (RSSI) and 217cm (read range). The tests generally demonstrated the strong and highly variable influence of ear tissue on the read range and RSSI of the transponders. Nevertheless, the results indicated that targeted detuning of UHF transponders can lower the influence of ear tissue on the reading performance, which is promising for the use of UHF-RFID in livestock farming. The method presented could be used in an optimised manner in the future to perform comprehensive tests and comparisons of different types of UHF transponder ear tags.

Wearable Flexible Lightweight Modular RFID Tag With Integrated Energy Harvester

A novel wearable radio frequency identification (RFID) tag with sensing, processing, and decision-taking capability is presented for operation in the 2.45-GHz RFID superhigh frequency (SHF) band. The tag is powered by an integrated light harvester, with a flexible battery serving as an energy buffer. The proposed active tag features excellent wearability, very high read range, enhanced functionality, flexible interfacing with diverse low-power sensors, and extended system autonomy through an innovative holistic microwave system design paradigm that takes antenna design into consideration from the very early stages. Specifically, a dedicated textile shorted circular patch antenna with monopolar radiation pattern is designed and optimized for highly efficient and stable operation within the frequency band of operation. In this process, the textile antenna’s functionality is augmented by reusing its surface as an integration platform for light-energy-harvesting, sensing, processing, and transceiver hardware, without sacrificing antenna performance or the wearer’s comfort. The RFID tag is validated by measuring its stand-alone and on-body characteristics in free-space conditions. Moreover, measurements in a real-world scenario demonstrate an indoor read range up to 23 m in nonline-of-sight indoor propagation conditions, enabling interrogation by a reader situated in another room. In addition, the RFID platform only consumes 168.3 $\mu \text{W}$ , when sensing and processing are performed every 60 s.