Ultra High Frequency Radio Frequency Identification Band Research Articles

Nature-inspired spider web shaped UHF RFID reader antenna for IoT and healthcare applications

This paper proposes a nature-inspired spider web-shaped ultra-high frequency (UHF) radio frequency identification (RFID) reader antenna and battery-free sensor-based system for healthcare applications. This antenna design consists of eight concentric decagons of various sizes and five straight microstrip lines.These lines are connected to the ground using 50 Omega resistors from both ends, except for one microstrip line that is reserved for connecting a feeding port. The reader antenna design features fairly strong and uniform electric and magnetic field characteristics. It also exhibits wideband characteristics, covering whole UHF RFID band (860–960 MHz) and providing a tag reading volume of 200 times 200 times 20 mm{^3}. Additionally, it has low gain characteristics, which are necessary for the majority of nearfield applications to prevent the misreading of other tags. Moreover, the current distribution in this design is symmetric throughout the structure, effectively resolving orientation sensitivity issues commonly encountered in low-cost linearly polarized tag antennas. The measurement results show that the reader antenna can read medicine pills tagged using low-cost passive/battery-free RFID tags, tagged expensive jewelry, intervenes solution, and blood bags positioned in various orientations. As a result, the proposed reader antenna-based system is a strong contender for near-field RFID, healthcare, and IoT applications.

Inkjet-Printed UHF RFID Sticker for Traceability and Spoilage Sensing of Fruits

This article presents an ink-jet printed ultrahigh-frequency (UHF) radio frequency identification (RFID) label for tagging fruits. The proposed tag antenna is based on a hybrid configuration, which consists of a loop, dipole-like strips (DLSs), and eye-shaped rectangular nested slots. The loop fulfills impedance matching proposes, while the eye-shaped slots assist to maintain high imaginary impedance to mitigate capacitive effects of high permittivity surfaces of fruits. Moreover, the dipole strips help to reduce the loss resistance caused by the high permittivity of the surface of the fruit. Therefore, the overall tag configuration provides a good impedance match with the Alien H3 RFID chip in the whole U.S. UHF RFID band. Furthermore, the fabricated prototype of the proposed tag antenna achieved a read range of 3 m after mounting on apple. Moreover, an automatic weighing and billing experiment is performed by placing the tagged apples inside a refrigerator. Overall, the performance of the proposed tag antenna is tested after mounting on apple fruits of different shapes and sizes, which indicates the robustness of this tag. Moreover, the tag antenna is also tested for sensing spoilage of apple fruits. The read range of the proposed tag antenna reduces up to 42% on spoiled apples. Therefore, this tag can be suitable for automatic sorting, weighting, and billing of fruits in smart cities, vending machines, and departmental stores.

Glasses frame‐based wearable antenna design for ultrahigh frequency radio frequency identification and Internet of Things applications using characteristic mode analysis

A novel ultra-high frequency (UHF) radio frequency identification (RFID) passive tag antenna based on a glasses frame is proposed for Internet of Things (IoT) applications. The glasses frame structure is exploited using characteristic mode analysis (CMA) to explore different modes for both 900 MHz and 2.4 GHz frequency bands. The proposed design consists of a glasses metallic frame and a loop for conjugate matching with an RFID chip (Alien Higgs H4). First of all, an already manufactured glasses metal frame structure is simulated in Computer Simulation Technology (CST) Microwave studio using CMA to get CM modes in the required RFID band. After that, a small loop is used along with the RFID chip as a capacitive coupling element to excite modes at 900 MHz by placing it at current minima. Moreover, the proposed tag antenna is also simulated with the voxel head model in CST and there is no significant change in impedance and reflection coefficient. The simulated specific absorption rate (SAR) is 0.5 W/Kg. Furthermore, the tag design is simulated with different glass materials and also with different frame structures to prove the robustness of the proposed solution. This tag design covers the entire US UHF RFID band (902–928 MHz) and features a read range of 2 m, measured using a UHF RFID reader setup with 4 W EIRP. Therefore, this antenna design can be a good candidate for future IoT technologies such as RFID, long range (LoRa), and other IoT applications.

High-Gain Circularly-Polarized Square Patch UHF RFID Reader Antenna Design for Smart Factory Applications

In this paper, a UHF (Ultra High Frequency) RFID (Radio-frequency identification) circular polarization reader antenna is presented. The proposed antenna is a low cost, easy to manufacture UHF RFID reader antenna in the European UHF RFID band. The proposed antenna design employs an air-substrate patch antenna. The antenna size of 250x250x7mm. The proposed antenna works from 850 to 874 and 880 to 893 MHz with return loss less than -10 dB, thus covering the European UHF RFID band. The proposed antenna return loss bandwidth is 37 MHz. The gain of the designed antenna is 7.88 dBi at 867 MHz. Also, with a bandwidth of 864-870 MHz, the axial ratio (AR) is less than 3dB. This means that the antenna has circular polarization at 867 MHz. Each result has been calculated on CST Studio Suite 2020. The antenna recommended for use in smart factory applications promises a good antenna among RFID reader antennas.

Right-Angled V-Shaped Conformal Dual-Patch Antenna Array for RAIN RFID Doorway Portals

This paper presents a conformal ultra-high-frequency (UHF) radio frequency identification (RFID) reader antenna array for doorway portal applications. The dual-patch antenna is only 100 mm wide and right-angled (V-shaped) to fit the corners of a regular portal. Patches are arranged orthogonally to create horizontal and vertical-linearly polarized fields at near-zones and at far-field distances they provide slant-polarized fields. Beam steering is enabled by phase delaying the array elements to enhance the field coverage within the doorway portal. The antenna operates in the European UHF RFID band (865-868 MHz) with a 38 MHz, 10 dB impedance bandwidth. The antenna’s azimuth and elevation half-power beamwidth is 90° and 130°. The azimuth beam is tilted to 35° from the boresight where the gain is peaked at 5.5 dBi. This antenna is low-profile, low-cost and flame retardant and paintable. Inherited properties of the antenna’s substrate make the antenna non-toxic, self-extinguishing, lightweight and highly chemical resistant. The reader antenna is compatible with both RAIN and non-RAIN alliance UHF RFID readers.

Near-Field Fractal RFID Reader Antenna for Item Level Tagging

This paper proposes a novel methodology for designing near-field fractal antenna operating at European Ultra-High Frequency (UHF) for Radio Frequency Identification (RFID) systems. The principle of Oppositely Directed Current (ODC) technique is implemented to generate homogeneous magnetic field above the surface area meant for near-field RFID application. The conceptual theoretical framework of the design based on the fractal structure can be applied. The fabricated RFID reader antenna operates at 867 MHz with reflection coefficient S11 -30 dB, thus the reader antenna covering UHF RFID band range. The reading capabilities of the antenna are determined by the interrogation area of, 190mm x 243mm. It is adequate for object tracking and detection systems in pharmaceutical management and chemical industries.

An Electromagnetically Induced Transparency Inspired Antenna Sensor for Crack Monitoring

The simultaneous communication and sensing based on antenna sensors are receiving increasing attention for pervasive monitoring in the internet of things (IoT). The open structure for high radiation limits the antenna’s sensitivity and resolution when it functions as an electromagnetic sensor. In this article, an antenna sensor operated in the ultra-high frequency (UHF) radio frequency identification (RFID) band is reported for structural health monitoring (SHM) applications. A loaded split-ring resonator (SRR) renders a low Q-factor bright mode for communication and two back-sited U-shaped strip resonators are embedded among high dielectric material, confining the near-field and yielding a high Q-factor dark mode for sensing. The two modes are proximity coupled and form an electromagnetically induced transparency (EIT)-like effect to achieve simultaneous communication and sensing in the narrow UHF RFID band. An enhancement around five times in the sensitivity can be observed resulting from the trapped field in the dark mode. The simulated sensitivity and the maximum peak realized gain of the proposed antenna sensor are around 3.0 MHz/mm2 and 3.77 dBi respectively. A prototype antenna sensor in a size of 42.0 mm $\times42.0$ mm $\times9.0$ mm is fabricated and measured. The detectability of surface crack using the proposed antenna sensor is experimentally validated by two case studies. The measured results demonstrate a sensitivity of 2.73 MHz/mm2 for crack depth characterization and a sensitivity of 2.75 MHz/mm2 for crack width characterization.

Fixed-Frequency Low-Loss Dielectric Material Sensing Transmitter

This article presents an all-in-one system for the detection of the relative permittivity of samples in direct contact with a sensor antenna, based on the frequency variation detection and using a cost- and energy-effective manner. In a specific application, in which the antenna should be in contact with the sensing material, characteristics of the antenna change with respect to the frequency spectrum for different materials. Conventionally, a frequency spectrum monitoring device is required to monitor these changes, and the sensing data should be obtained by postprocessing the observation. The proposed system converts the sensing information in the frequency response of the device to a voltage, which can be utilized further for transmission as well as compensating and frequency retuning the system. The sensor antenna loads the radio frequency oscillator at the transmitter resulting in a change at the operating frequency of the system. A small portion of the signal is sampled and used for recovery in a phase/frequency comparator (PFC). The output of the PFC is a voltage corresponding to the difference between the operating frequency and the reference signal. The proposed sensor system is fabricated at the 915-MHz ultrahigh-frequency radio frequency identification band using on-off keying modulation as an evaluation, and the measured results with some known samples are presented. Since the proposed technique is implemented by utilizing the building blocks of a conventional transmitter, the power consumption and cost of the system are kept intact.

Scalable Near-Field Fed Far-Field RAIN RFID Reader Antenna for Retail Checkout Counters

This article presents a scalable ultra-high-frequency (UHF) radio frequency identification (RFID) reader antenna for retail checkout counters. The antenna’s simultaneous near-field and far-field operation enable effortless and reliable asset identification. Two meandered microstrip lines that are 90° out-of-phase form the near-field antenna rim around a far-field patch antenna. The patch antenna is fed by those meandered lines along the vertices on its orthogonal points, resulting in circular polarization. The near-field radiation is evenly distributed with no surface dead zones, and the far-field radiation pattern is symmetrical with a 90° half-power beam-width in both azimuth and elevation planes. The antenna operates in the North American UHF RFID band (902-928 MHz) with a 50 MHz impedance bandwidth. Fabricated antenna’s gain and axial ratio at the band’s center frequency of 915 MHz is 3.3 dBi, and 1.4 dB, respectively. This antenna is low-profile, low-cost and recyclable as it is constructed from polyolefin substrate and copper foils. The antenna is pragmatic, scalable with increasing checkout counter sizes and insusceptible to proximity assets and metal frames.

Multipolarized Reader Antenna With Periodic Units Based on Electric Field Coupling for UHF RFID Near-Field Applications

This paper presents a multipolarized reader antenna with periodic units based on electric field coupling for near-field applications of ultra-high frequency (UHF) radio frequency identification (RFID). The antenna units are composed of two branches that are mirror-symmetric with respect to the ${x}$ -axis and produce ±45° linear polarization. A 90° phase difference is produced between the upper and lower branches by introducing a phase shifter into the upper branch, so that the near-field electric fields excited in the horizontal plane exhibit a quasi-circular polarization distribution. The proposed design is validated by simulations and experiments using prototype 4-unit and 6-unit antennas. The proposed antennas can generate strong and uniform electric fields and provide reading volumes of 400 mm $\times \,\,320$ mm $\times \,\,300$ mm and 560 mm $\times \,\,320$ mm $\times \,\,300$ mm for the 4-unit and 6-unit antennas, respectively, regardless of the orientation of the tags in the horizontal plane. In addition, the far-field gain is low with a maximum of −6 dBi, thus the misreading of tags outside the reading region is avoided. The proposed antenna achieves impedance matching over the Chinese UHF RFID band (920–925 MHz) and therefore meets the application requirements of near-field RFID reader antennas.

UHF meander bowtie antenna for RFID application

This paper describes the development of four different ultra-high frequency (UHF) radio frequency identification (RFID) tag antenna using polycarbonate material or transparent paper as the substrate and aluminum tape as the radiating element. The main advantage of the method is that the materials are easy to obtain where it can be found in any hardware stores or in any general online shop. Plus, the antennas are designed in such a way that a meander line is traced along the shape of a bowtie antenna so that the antenna would operate at UHF band. The results of all four of the tag antenna designs are discussed and compared using graph obtained from Computer Simulation Technology (CST) simulation results and measurement results obtained from a portable Vector Network Analyzer (VNA) for the reflection coefficient, S 11 , and measurement results taken from VNA in chamber room for the radiation pattern. Finally, the results show that the measured results are in agreement with the simulated result and that the UHF RFID tag antennas are able to operate at UHF RFID band.

UHF meander bowtie antenna for RFID application

This paper describes the development of four different ultra-high frequency (UHF) radio frequency identification (RFID) tag antenna using polycarbonate material or transparent paper as the substrate and aluminum tape as the radiating element. The main advantage of the method is that the materials are easy to obtain where it can be found in any hardware stores or in any general online shop. Plus, the antennas are designed in such a way that a meander line is traced along the shape of a bowtie antenna so that the antenna would operate at UHF band. The results of all four of the tag antenna designs are discussed and compared using graph obtained from Computer Simulation Technology (CST) simulation results and measurement results obtained from a portable Vector Network Analyzer (VNA) for the reflection coefficient, S 11 , and measurement results taken from VNA in chamber room for the radiation pattern. Finally, the results show that the measured results are in agreement with the simulated result and that the UHF RFID tag antennas are able to operate at UHF RFID band.

Compact Crossed Dipole Antenna With Meandered Series Power Divider for UHF RFID Tag and Handheld Reader Devices

A low-profile and meandered crossed dipole antenna design for ultrahigh-frequency (UHF) radio-frequency identification (RFID) circularly polarized (CP) tag or handheld reader application is described in this communication. The crossed dipole CP condition is obtained by employing a series power divider meandered at the center of the dielectric substrate, and a surrounding ring which acts as a T-match network guarantees impedance matching. The series power divider alleviates the problem of using a balun when the crossed dipole is fed with a 50 $\Omega $ coaxial cable. A prototype has been manufactured on a $56\times 56\times0.4\,\,\text {mm}^{3}$ FR4 dielectric substrate, and the measurement results show a $S_{11}\le -10$ dB bandwidth of more than 14.4% (865.6–1000 MHz), an axial ratio (AR) ≤ 3 dB bandwidth of 2.8% (906–932 MHz) which can essentially cover the Federal communications commission (FCC) UHF RFID band, and a broadside RHCP peak gain of 1.4 dBic at 919 MHz. When the antenna is connected to an RFID tag chip, excellent read range performance within the whole 902–928 MHz bandwidth has been demonstrated (with maximum values of 7 and 9.9 m when interrogated with a linearly polarized and a CP reader antenna, respectively).

A Smart Blood Bag Management System Using a Load-Integrated U-Shaped Near-Field RFID Antenna Array

For improving transfusion safety, a smart blood bag management system using a load-integrated U-shaped near-field antenna (LUNA) array is proposed in this paper. The proposed system consists of four LUNAs for ID sensing with blood information and a switching circuit for the sensing of blood bag localization. The LUNA, which is well impedance-matched within the universal ultrahigh-frequency radio frequency identification band, operates in the near-field region for precise localization, and includes a lumped Lattice-type $LC$ -balun which is exploited to cancel out currents through the ground plane of the LUNA and to obtain opposite directional currents in order to reinforce the magnetic field between two microstrip lines in the LUNA. Using a single-pole four-throw switching circuit, a centimeter-level precise localization of blood bags can be achieved. The proposed system can be used to prevent the mishandling of blood transfusions and to manage blood bags remotely and effectively.

Flexible Radio-Frequency Identification (RFID) Tag Antenna for Sensor Applications.

In this paper, an inkjet-printed flexible Radio-Frequency Identification (RFID) tag antenna is proposed for an ultra-high frequency (UHF) sensor application. The proposed tag antenna facilitates a system-level solution for low-cost and faster mass production of RFID passive tag antenna. The tag antenna consists of a modified meander line radiator with a semi-circular shaped feed network. The structure is printed on photo paper using silver nanoparticle conductive ink. The generic design outline, as well as tag antenna performances for several practical application aspects are investigated. The simulated and measured results verify the coverage of universal UHF RFID band with an omnidirectional radiation pattern and a long-read range of 15 ft. In addition, the read range for different bending angles and lifetimes of the tag antenna are also demonstrated.

A miniaturized ultra‐high frequency microstrip traveling wave antenna Array for cm‐level two‐dimensional identification and position detection systems

AbstractIn this article, a miniaturized ultra‐high frequency (UHF) microstrip traveling wave antenna (TWA) array for cm‐level 2D identification (ID) and position detection systems is proposed. The proposed miniaturized TWA array with nine reading zones for ID and position detection systems has been reduced in size by utilizing LC‐baluns and a microstrip TWA array. It covers the authorized universal UHF radio frequency ID band (840‐960 MHz), has low insertion loss (0.8 dB), and high isolations between TWAs are ≤30 dB. The sensing precision of the proposed TWA array is approximately 1.5 cm and its physical size is 95 × 95 mm2 (~1/4 λ0 at 915 MHz).

On‐metal UHF‐RFID passive tags based on complementary split‐ring resonators

The use of complementary split-ring resonators (CSRRs) as radiating elements in low-profile on-metal ultra-high-frequency radio-frequency identification (UHF-RFID) tags is explored in this study. First, the radiation properties of the edge-coupled and the non-bianisotropic (NB-CSRR) versions of the CSRR are studied. The tag design strategy is then discussed in detail. On that basis, a compact (λ 0/7 × λ 0/7) low-profile (1.27 mm) tag prototype based on the non-bianisotropic version of the CSRR (NB-CSRR) antenna is designed and manufactured to operate in the North-American UHF-RFID band. The experimental results validate the theoretical and simulated behaviour, and exhibit a maximum read range of 6.8 m.

Compact design of UHF RFID and NFC antennas for mobile phones

A small size and low-profile antenna has been developed in order to provide any mobile phone with ultra-high frequency (UHF) radiofrequency identification (RFID) reader functionality. For that purpose, a patch antenna topology has been chosen on account of the mobile phone battery, which exhibits an electromagnetic behaviour similar to a metal plane. The low-profile patch antenna has been designed to operate at the European UHF RFID band. To communicate the mobile phone with the RFID reader module, near-field communication (NFC) technology has been considered. Thus, an NFC antenna, based on square coils, operating at 13.56 MHz has been also designed. Such antenna has been etched on the opposite side of the patch antenna. Overall dimensions of the prototype are 60 mm × 100 mm, i.e. small enough to fit the dimensions of a mobile phone. As proof of concepts to evaluate the performance of the designed antennas, an UHF RFID reader module and an NFC reader module are tested. The measured read range reaches up to 1 m for some commercial tags.

Design and development of wideband patch antenna for UHF RFID metal mountable tag

ABSTRACTIn this research, two low profile metal mountable patch antenna designs for passive ultra-high frequency (UHF) radio frequency identification (RFID) tag are proposed. The complex impedance matching between the antenna and the referenced microchip, Alien-Higgs 3 whose impedance , is realized through an inductively coupled loop feed structure where it provides the needed reactance for the tag antenna. To enhance the bandwidth of the antenna, multiple co-planar radiating patches are employed to excite several resonant modes for worldwide use. The wide impedance bandwidth also compensates for fabrication inaccuracy which could shift the operating frequency of the final antenna design. The final dimensions of the antennas are 87 × 45 × 1.6 mm3 and 130 × 63 × 1.6 mm3. The measured impedance bandwidths of the proposed antennas when mounted on a metal plate are 155 MHz (RL ≥ 3 dB), which is from 830 to 985 MHz, and 117 MHz (RL ≥ 6 dB), which is from 850 to 967 MHz, respectively. The maximum simulated gains are −7 and −11 dB at the operating frequency of 915 MHz. Based on the measurement results, it is expected that the proposed antenna would be able to provide a reasonable read range of at least 2 m throughout the entire UHF RFID band when being attached on metal objects.

Magnetic Tag Antenna for UHF Near-field and Far-Field RFID Applications

A novel broadband magnetic Tag antenna for ultra-high frequency (UHF) near-field (NF) and far-field (FF) radio-frequency identification (RFID) applications is presented. This antenna is printed on an Rogers RT/duroid 5880 substrate with an overall size of 68 × 19.7 × 0.787 mm. The simulated bandwidth of the proposed Tag antenna is more than 100 MHz (860960MHz), which can cover the entire UHF RFID band. The proposed structure can generate a strong and uniform H-field distribution in the region around the antenna. The minimum power required to activate the Tag at 900 MHz is approximately of -12.6 dBm in the near-zone (18 cm) and 2.8 dBm in the far-zone (65 cm) in anechoic chamber. The measured read range is about 15 m when the transmission power level is 25 dBm in open environment. Measurements show that the antenna operating confirms good performance of Tag identification for near-field and far-field UHF RFID applications.