Radio Frequency Identification Band Research Articles

A Compact and Robust RFID Tag Based on an AMC Structure.

A platform-tolerant RFID (Radio-Frequency Identification) tag is presented, designed to operate across the entire RFID band. This tag utilizes a small Artificial Magnetic Conductor (AMC) structure as a shielding element for an ungrounded RFID tag antenna. It can be easily mounted on various surfaces, including low permittivity dielectric materials, metal objects, or even attached to the human body for wearable applications. The key features of this RFID tag include its ability to be tuned within the worldwide RFID band, achieving a maximum theoretical read range of over 11 m. Despite its advanced capabilities, the design emphasizes simplicity and cost-effective manufacturing. The design and simulations were conducted using CST Studio Suite.

Design and analysis of flexible embroidered UHF-RFID tag on facemask for IoT applications using characteristics mode analysis

This work presents an ultra-high frequency (UHF) radio frequency identification (RFID) tag embroidered on a face mask for Internet of Things (IoT) devices. The tag is designed and optimized to operate within the entire US RFID band of 902–928 MHz using characteristic mode analysis (CMA). A Mickey Mouse (MM) shaped radiation element is analyzed by testing three resonating modes at frequency of 900 MHz. Additionally, two dipoles are introduced to achieve the optimal conjugate match with a passive RFID chip (Alien Higgs H3), which exhibits an impedance of 27-200j at the desired frequency. A simulation of the voxel head model has also been carried out to verify the specific absorption rate (SAR), which provides SAR <1.43 W/kg. The proposed tag is embroidered on a cotton fabric facemask with a dielectric constant of 1.143 using conductive thread with a resistance of 28 O/ft. This tag features a good impedance match in US RFID band along with gain of 2.06 dB and a 37% reduction in size as compared to the previous version. Furthermore, it provides a read range of 3 m for an off-body scenario and 2.5 m for an on-body scenario. The proposed wearable facemask tag has potential applications for various real-life applications.

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.

Bio-Inspired Circular-Polarized UHF RFID Tag Design Using Characteristic Mode Analysis

This paper presents a bio-inspired circularly polarized ultra-high frequency (UHF) radio frequency identification (RFID) tag antenna for metallic and low-permittivity substances. This tag design is based on a leaf-shaped radiator, two shorting stubs and slots etched on F4B substrate. Initially, the tag antenna is designed using characteristics mode analysis (CMA) by analyzing the first six CM modes and characteristic angles. The width of orthogonal slots is varied to get the resonance of CM modes in the required US RFID band. Moreover, the edges are blended to get orthogonal current distribution, which is necessary for circular polarization. Additionally, the proposed tag design is optimized further using CST Microwave studio and an RFID chip is exploited as a capacitive coupling element (CCE) to run CM modes with the orthogonal current pattern. This tag can also be tunable to European RFID (EU) band (866 – 868 MHz) by changing the length of shorter diagonal slot. The tag design offers a read range of 7 m and 4.5 m on 100 × 100 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> metals plate and low-permittivity substrates, respectively (for 902 – 928 MHz band). In EU band, the corresponding read ranges are 5.7 m and 3.5 m above metal and low-permittivity objects, respectively. This circularly polarized tag antenna is advantageous in terms of cost, circular polarization feature, and ease of fabrication due to the absence of vias, shorting pins, and matching circuits. Therefore, this tag design is suitable for labeling various low-permittivity objects, industrial conveyer belt applications, baggage handling systems, and IoT applications.

Systematic design and prototyping of a low‐cost passive UHF‐RFID transponder

AbstractThis paper presents a methodical design and prototyping of a passive European ultra‐high frequency (UHF) band radio frequency identification (RFID) transponder. The transponder has a 70 × 17 × 0.3 mm3 copper antenna whose design is based on the folded dipole architecture and utilizes techniques such as meandering and end loading to match a Texas Instruments (TI) UHF‐RFID chip through a T‐match feeding network. The tag's simulated and measured performances indicate good coverage of the entire UHF band with a return loss better than 10 dB. The transponder was then fabricated using inexpensive off‐the‐shelf materials and its performance was tested. The proposed tag achieved good gain, read range, and cost efficiency when compared with current folded dipole antennas and can be easily adapted for various applications such as supply chain, access or security, and vehicle identification.

A universal UHF near‐field RFID reader antenna with wide bandwidth and adjustable reading area

AbstractA universal ultrahigh‐frequency (UHF) near‐field radio‐frequency identification (RFID) reader antenna with wide bandwidth and adjustable reading area is proposed in this letter. The antenna consists of an inverting power splitter base on double‐sided parallel stripline and adjustable traveling‐wave near‐field radiation units, which consists of two symmetrical meander microstrips and a complementary open resonant ring loaded on the ground plane. A design example with three radiation units is simulated, fabricated, and tested for verification. The result indicates that the proposed antenna has the 10‐dB impedance bandwidth of 128%, which completely covers the universal UHF RFID band from 840 to 960 MHz. The 100% read–write rate is achieved within the read–write distance of 10 mm according to the reading test. The reading area of 731 × 120 mm2 can be obtained for increasing the number of radiation units to 10. Moreover, the antenna features low far‐field gain, low‐cost, strong and uniform magnetic field distribution. Therefore, the proposed antenna and design method have good application prospects in the Internet of Things.

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.

Design and analysis of broadband circularly polarized compact planar antennas for 2.45 GHz RFID handheld reader applications

AbstractIn 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.

An RFID-Based Wireless Vibration and Physical-Shock Sensing System Using Edge Processing

This article presents energy-efficient edge processing for an ultrahigh-frequency (UHF) band radio-frequency identification (RFID)-based vibration frequency/ physical shock sensing system. This system is especially useful for long-term measurements. In this edge processing system, an RFID reader has a standby mode operating at a low duty cycle and an active mode operating at a high duty cycle. With these modes, an RFID reader achieves both energy-efficient operations and accurate sensing performance. The standby mode is useful for reducing energy consumption, preventing overheating, and reducing greenhouse gas emissions because a low duty cycle leads to a short radio wave irradiation time. Reducing the heat generation of the RFID reader, especially for long-term measurements, the standby mode makes the RFID reader durable. If vibration/physical shocks are applied to the RFID sensor tag, then the standby mode triggers the active mode. The standby mode samples the presence of the RFID sensor tags within an experimentally determined sampling period to detect the beginning of vibration/physical shocks. A high-duty cycle in the active mode results in an increased number of RFID sensor tag readings. Because the proposed edge processing keeps measured data only for the active mode, the amount of data uploaded to the Internet-of-Things (IoT) cloud is reduced. The proposed method was experimentally evaluated by monitoring walking behaviors and a refrigerator. The vibration sensing capability was mainly validated by monitoring a refrigerator, and the physical shock sensing capability was evaluated by monitoring walking behaviors by a human examinee.

A Loop Antenna Array With an Enlarged Near-Field Interrogation Zone for UHF RFID Near-Field and Far-Field Applications

This letter presents a loop antenna array for ultrahigh frequency near-field and far-field radio frequency identification (RFID) reader applications. The antenna array consists of several microstrip collinear loop antennas, and each loop antenna is composed of several periodic radiating units. By deploying microstrip collinear radiating units, a novel loop antenna with in-phase radiating currents is realized, which generates a strong and uniform magnetic field over a large interrogation area and a horizontally polarized omnidirectional radiation. By configuring the array antenna, the magnetic fields distribute on the entire antenna array and create an enlarged near-field reading area. The far-field coverage is enlarged by the superposition of omnidirectional radiation. The antenna array is simulated and validated with a four-element prototype made on FR-4 substrates. The antenna array is measured to have a −10 dB impedance bandwidth from 802 to 963 MHz with an enlarged near-field reading volume of 280 × 280 × 540 mm and a far-field gain of 6.66 dBi at the UK RFID band.

Compact circularly polarized cross dipole antenna for RFID handheld readers/IoT applications

The radio frequency identification (RFID) and global positioning system (GPS) are employed for indoor and outdoor tracking scenarios. This paper presents an amalgamated identification mechanism for sensing and tracking in an Internet of things (IoT) network. A low-profile, compact, multi-functional antenna configuration is proposed for the amalgamation application. The antenna operates in the 915 MHz (UHF), 2.45 GHz, and 5.8 GHz RFID bands, along with the 1.575 GHz GPS L1 band. The presented antenna is a cross dipole configuration consisting of three pairs of dipole elements printed on both sides of the dielectric substrate. The first and third dipole pairs are larger and smaller metal strips with half-arrow shaped ends that excite the 915 MHz and 5.8 GHz bands, respectively. The second dipole pair is an asymmetric triangular-shaped radiator that excites the 1.575 GHz and 2.45 GHz bands. Using quarter wavelength ring delay lines, circular polarization is obtained in each band. The GPS band, in combination with the RFID bands, improves the efficiency and accuracy of the reader tracking device. The proposed multiband antenna prototype is fabricated on the 45° rotated substrate material, resulting in a compact size of 0.21λ0 × 0.21λ0 × 0.004λ0. The antenna simulation and measurement results are in close agreement.

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.

Graphene-Based RFID Tag Antenna for Vehicular Smart Border Passings

Globalization has opened practically every country in the globe to tourism and commerce today. In every region, the volume of vehicles traveling through border crossings has increased significantly. Smartcards and radio frequency identification (RFID) have been proposed as a new method of identifying and authenticating passengers, products, and vehicles. However, the usage of smartcards and RFID tag cards for vehicular border crossings continues to suffer security and flexibility challenges. Providing a vehicle's driver a smartcard or RFID tag card may result in theft, loss, counterfeit, imitation, or vehicle transmutation. RFID sticker tags would replace RFID tags as vehicle border passes to solve the mentioned problem. The RFID sticker tag adheres to the windscreen, side screen, dash, hood, or door of the vehicle, or any other acceptable location. Any damage or stripping from the installed location may cause data corruption and cannot be reused. Overall, these sticker tags will make the border crossings more secure and efficient. This article focuses on designing a rectangular-shaped RFID sticker tag antenna made of graphene sheets as a possible solution for smart border crossings. The proposed antenna is mathematically designed and analyzed with CST software to determine the optimum parameters. The design parameters are then used to create an antenna on a prepared graphene sheet. The performance results are carried out with CST software and a network analyzer. The designed RFID antenna stick on a car windscreen offers approximately 900 MHz bandwidth over the frequency range from 1.8 GHz to 2.7 GHz with an average gain of 1.23 dBi at the frequency to be used of 2.4 GHz microwave RFID band. The radiation is an omnidirectional pattern. The proposed graphene-sheet rectangular-shape monopole antenna is compact, low-cost, and bendable to fit into the windscreen of a car while retaining excellent wave propagation capabilities. These findings illustrate the suggested antenna's potential as an RFID tag antenna in a vehicular smart border pass system.

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.

Stretchable Textile Yarn Based on UHF RFID Helical Tag

In the context of wearable technology, several techniques have been used for the fabrication of radio frequency identification (RFID) tags such as 3D printing, inkjet printing, and even embroidery. In contrast to these methods where the tag is attached to the object by using sewing or simple sticking, the E-Thread® technology is a novel assembling method allowing for the integration of the RFID tag into a textile yarn and thus makes it embeddable into the object at the fabrication stage. The current E-Thread® yarn uses a RFID tag in which the antenna is a straight half-wave dipole that makes the solution vulnerable to mechanical strains (i.e., elongation). In this paper, we propose an alternative to the current RFID yarn solution with the use of an antenna having a helical geometry that answers to the mechanical issues and keeps quite similar electrical and radiative properties with respect to the present solution. The RFID helical tag was designed and simulated taking into consideration the constraints of the manufacturing process. The helical RFID tag was then fabricated using the E-Thread® technology and experimental characterization showed that the obtained structure exhibited good performance with 10.6 m of read range in the ultra high frequency (UHF) RFID band and 10% of tolerance in terms of elongation.

UHF RFID Conductive Fabric Tag Design Optimization.

This paper presents the design of a 920 MHz Ultra High Frequency (UHF) band radio frequency identification (RFID) conductive fabric tag antenna. The DC (Direct Current) resistance and impedance of the conductive fabric are measured by a DC multimeter and by a network analyzer at a UHF frequency band. The conductivities of the fabrics are calculated with their measured DC resistance and impedance values, respectively. The conductivities of the fabric are inserted into the CST simulation program to simulate the fabric tag antenna designs, and the results of the tag designs with two conductivities are compared. Two fabric UHF RFID tag antennas with a T-Matching structure, one with the name-tag size of 80 × 40 mm, and another with 40 × 23 are simulated and measured the characteristics of tag antennas. The simulated and measured results are compared by reflection coefficient S11, radar cross-section and reading range. The reading range of the 80 × 40 mm fabric tag antenna is about 4 m and 0.5 m for the 40 × 23 size tag. These fabric tags can be easily applied to an entrance control system as they can be attached to other fabrics and clothes.

Compact Dual-Band Circularly Polarized Stacked Patch Antenna for Microwave-Radio-Frequency Identification Multiple-Input-Multiple-Output Application

A compact, low-profile, two-port dual-band circularly polarized (CP) stacked patch antenna for radio-frequency identification (RFID) multiple-input-multiple-output (MIMO) readers is proposed, which employs the shared-aperture technique. The proposed antenna adopts a 1.524 mm thickness Rogers Ro4350b substrate with relative permittivity of 3.48. Two pairs of isolated ports are working at two microwave- (MW-) RFID bands (2.4–2.485 GHz and 5.725–5.875 GHz) with high port isolation of 25 dB and 30 dB, respectively. A shared metal slot layer is designed to separate two feeding structures of the lower band and upper band for port isolation enhancement as well as saving space. Corner-truncated square slot and patch configurations have been designed to obtain CP modes. In the lower and upper MW-RFID bands, the relative impedance bandwidths are 12.2% and 5.7%, and the maximum realized gains are higher than 7.3 dBic. Moreover, two-element configurations have been combined for an RFID MIMO system that occupies a dimension of 119 mm × 119 mm × 12.9 mm. The MIMO antenna performance of envelope correlation coefficient (ECC) is lower than 0.03, and diversity gain is close to 10 dB.

A UPF-PS SLAM Algorithm for Indoor Mobile Robot With NonGaussian Detection Model

In this article, we propose a simultaneous localization and mapping (SLAM) framework that combines the methods of the unscented particle filter (UPF) and particle smoothers (PS). The UPF is used to estimate the position and orientation of the mobile robot and PS are used to update the locations of landmarks. We show that UPF is capable of estimating the pose of the robot more consistently and accurately than generic particle filter and unscented Kalman filter (UKF) do, especially when the dynamic models of the robot are highly nonlinear or noises are nonGaussian. Then, the proposed SLAM framework is applied to high-frequency (HF) band radio-frequency identification (RFID) system. Since detection model of the HF band RFID system is highly nonGaussian, the traditional SLAM frameworks with the Gaussian assumption are not suitable and the proposed UPF-PS framework presents the superior performance. The proposed SLAM framework is evaluated through simulated experiments with an HF band RFID system and a range and bearing sensor. The comparisons between the proposed SLAM framework and four other SLAM frameworks, i.e., FastSLAM, UFastSLAM, and P-SLAM 1.0 and 2.0 are also given. Finally, the proposed SLAM framework is verified in a real experimental environment. The experimental results validate the effectiveness and superiority of the proposed SLAM framework.

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.