Ultra High Frequency Radio Frequency Identification Applications Research Articles

Circular Polarized Antenna with Rotationally Positioned Microstrip Structures For UHF RFID Applications

With the use of wireless communication and the industry 4.0 revolution, RFID technology integration in production has increased. The large-scale preference of RFID systems is both cost-effective and significantly increasing production. It is an innovation that provides convenience for large production facilities such as product control, in-plant tracking, storage, inventory operations. In this paper, a compact circularly polarized (CP) reader antenna is presented for ultra-high frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna consists of a circularly slotted ground plane and folded plus-shaped structures with vertical and horizontal positions. Microstrip line feeding technique is used in the vertically folded plus-shaped structure positioned on the front surface. The antenna has a 10 dB return loss bandwidth of 80 MHz (840-920) and a 3 dB axial ratio bandwidth of 20 MHz (855-875). Theproposed antenna has dimensions of 75 × 75 × 1.6 mm3 . The size advantage of the single-layer and singlefed structure enables its applicability in portable systems.

High Gain Passive UHF RFID Reader Antenna Using Novel FSS for Longer Read Range

Frequency Selective Surface (FSS) is widely used to enhance the gain of antenna & reduces Electromagnetic Interference (EMI). In this work, a novel Frequency Selective Surface (FSS) is designed, analyzed, and fabricated along with passive Radio Frequency Identification (RFID) reader antenna operating at global Ultra-High Frequency (UHF) for wireless RFID applications. The antenna & FSS sheet is fabricated on less costly FR4 substrate with resonant bandwidth of 860–960 MHz. The Fabry–Perot arrangement of FSS sheet with antenna increases the gain & directivity without modifying the antenna profile or increasing radiation patch size. The maximum measured gain is 9.8 dB & 7.2 dB with the Reflection coefficient (S11) of −35 dB & −15 dB at 910 MHz & 950 MHz respectively. The proposed antenna of dimension 40 mm by 40 mm is fabricated & tested for further experimental validation with measured read range longer than 8 m. The novelty in proposed work is integration of FSS with passive UHF RFID technology which can be effectively used in wireless RFID applications for improved read range, higher gain, lower power consumption & better immunity within the resonating band. The proposed antenna effectively isolates out-of-band frequencies from in-band frequencies over a required bandwidth reducing Electromagnetic Interference (EMI) for UHF RFID applications.

A Novel RFID Localization Approach to Smart Self-Service Borrowing and Returning System

The misreading problem of a passive ultra-high-frequency (UHF) radio frequency identification (RFID) tag is a frequent problem arising in the field of librarianship. Unfortunately, existing solutions are something inefficient, e.g., extra resource requirement, inaccuracy, and empiricism. To this end, under comprehensive analysis on the passive UHF RFID application in the librarianship scenario, a novel and judicious approach based on RFID localization is proposed to address such a misreading problem. Extensive simulation results show that the proposed approach can outperform the existing ones and can be an attractive candidate in practice.

A Fully Integrated Passive Self-Jamming Cancellation Architecture with Fast Settling Time for UHF RFID Reader

This paper presents a fully integrated passive self-jamming cancellation (SJC) circuit in 0.18 µm Complementary Metal Oxide Semiconductor (CMOS) technology for ultra-high frequency (UHF) radio frequency identification (RFID) applications. Based on the active amplitude and phase control, a novel passive variable capacitor array and signal combiner are adopted instead of a traditional variable amplifier/attenuator and a phase shifter to reduce the circuit complexity and thus achieve higher linearity and low noise. We use an improved cancellation algorithm based on the local search method to quickly and accurately find the cancellation point that minimizes the self-jamming signal power. The simulation and measurement results are constant, and a suppression of 38 dB can be achieved in the working frequency of 860–960 MHz. The cancellation algorithm can be finished within 0.5 ms. These results indicate that the designed SJC circuit can be a promising candidate for UHF RFID applications.

Frequency Reconfigurable Smart Antenna With Integrated Electroactive Polymer for Far-Field Communication

For the first time, the ionic polymer metal composite (IPMC) actuator is integrated with a radio frequency identification (RFID) tag antenna for achieving frequency reconfiguration in the ultrahigh-frequency (UHF) band. Here, the IPMC movable flap serves as an actuator that can effectively tune the tag resonant frequency. By applying a two-layer-crenelated structure and employing a surface patterned electrode for restraining back relaxation, the deflection of the IPMC actuator can be significantly improved. The IPMC actuator can move in two directions, enabling two-degree frequency tuning. Numerical and experimental data confirm that the tip displacement of the IPMC actuator can be enhanced up to 266% with the use of the two-layer-crenelated structure. The IPMC actuator allows the resonant frequency of the tag antenna to be tuned back by as much as 35 MHz, after deviating due to placing on an unintended object. UHF RFID application is also performed using a portable commercial RFID reader. Good frequency reconfiguration and broad tuning range, along with far read distances, have been achieved with our tunable UHF RFID tag antenna.

Planar hexagonal broadband near‐field antenna for UHF RFID application

In the design of ultra-high-frequency (UHF) radio frequency identification (RFID) near-field antennas, realising an antenna with electrically large size, wide frequency band, and far read range has always been a challenge. To solve these problems, a planar hexagonal broadband near-field antenna for UHF RFID applications is proposed and investigated. The antenna structure is composed of six dipoles (resembles three sets of double-arrow structures) that are printed on the top and bottom surfaces of an FR4 substrate, forming a dual-layer (inner and outer layers) broken hexagonal loop. The 10 dB return loss bandwidth of the proposed antenna can reach up to 20.8% (856–1055 MHz), thus able to cover the entire European Telecommunication Standards Institute and Federal Communication Commission system operating bands. Since the current distribution along the loop is kept in a single direction and the length of each dipole is ∼1/2 wavelength (λ), strong and uniform z-component magnetic field distribution with an 18 cm read range can be obtained in the near-field zone of the antenna. As the proposed near-field antenna has a planar size of 175 mm × 175 mm, it is suitable for multi-system and wide-range RFID applications.

RFID over low cost VCSEL‐based MMF links: experimental demonstration and distortion study

Radio-over-fibre (RoF) distributed antenna system (DAS) technology has been investigated for the distribution of ultra-high frequency (UHF) radio frequency identification (RFID) signals. RoF DAS allows for reduced number of readers and centralised placement of readers which facilitates easy system maintenance, but it is important to find a low-cost solution that can achieve comparable performance to a conventional RFID system. In this work, a low-cost vertical-cavity surface-emitting laser (VCSEL)-based multimode fibre (MMF) link has been developed and demonstrated for passive UHF RFID applications. The reported results show almost the same performance when compared with a conventional RFID system. In addition, simple spatial antenna diversity schemes are tested, with improved performance reported in comparison with an RFID-RoF system without diversity. Also, an investigation of RFID over fibre with RoF non-linearity is carried out showing that phase-reversal amplitude shift keying (PR-ASK) RFID modulation allows for higher levels of RF carrier and modulated signal power than the ASK RFID, for low levels of non-linearity.

Standards for Passive UHF RFID

Passive ultra-high frequency (UHF) radio frequency identification (RFID) technology has been widely adopted by retail and other industries for serialized item-level identification and data sharing. This article introduces the standards that support and define all procedures in various passive UHF RFID applications. Electronic Product Code (EPC) Radio-Frequency Identity Protocols Generation-2 UHF RFID Standard, or C1G2, is a foundational standard that defines the format, encoding, and procedures within the air interfaces of RFID systems. Low Level Reader Protocol provides a standard and portable interface between different applications and RFID readers from different vendors. The format and encoding of the EPC information are defined by the EPC Tag Data Standard, which enables each tag to be uniquely identified (e.g., item-level identity of many goods in a warehouse). Additional protocols, such as Discovery, Configuration and Initialization and Reader Management, specify and clarify more processes (e.g., the management of many readers) that can be deployed in various business applications. We provide a general introduction of passive UHF RFID technology standards and review each protocol's features and procedures.

Novel Miniaturized Folded Line Antenna for Passive UHF RFID Tags

RFID (Radio Frequency IDentification) in UHF (Ultra High Frequency) has received considerable attention due to the different advantages offered in various fields. The tags in this technology must be attached to small objects. Therefore, the antennas size needs to be miniaturized without significant degradation. In this paper, a novel miniaturized tag antenna for UHF RFID applications is presented. The miniaturized antenna is composed of a folded line and an inductively coupled feeding loop: the antenna line is folded to reduce the antenna size, and the inductively coupled loop is used to match the antenna impedance to the chip to maximize power transfer. The miniaturized antenna is designed to operate in the USA band at around 915 MHz, and printed on a polyester substrate with a thickness of 50 µm. The performances of the proposed antenna regarding impedance, reading distance, return loss and antenna gain are evaluated using a 3D electromagnetic simulators HFSS (High Frequency Structure Simulator) and CST-MWS (Computer Simulation Technology-MicroWaves Studio) and are compared to those achieved by the conventional dipole antenna with an inductively coupled loop.

Multiple‐port reader antenna with three modes for UHF RFID applications

A multiple-port reader antenna for ultra-high frequency (UHF) radio-frequency identification (RFID) near-field and far-field applications which has three modes is proposed and studied. Three fed-ports are designed into the structure, which provide different radiation properties. Specially, far-field radiation for two orthogonal polarisations and near-field operation based on magnetic field coupling can be modified by feeding different corresponding port. The RFID reader antenna can work at three different operations within 820–880 MHz, including European UHF (865–868 MHz) and Chinese UHF (840–845 MHz) bands. Design details, simulation, and measured results are also presented.

Multiobjective Optimization Design for Electrically Large Coverage: Fragment-Type Near-Field\/Far-Field UHF RFID Reader Antenna Design

The design of an ultrahigh-frequency (UHF) radio-frequency identification (RFID) reader antenna covering an electrically large near-field area is challenging for near-field UHF RFID applications. In such a design, magnetic field distribution on a large coverage area is required to be as uniform as possible. For some specific UHF near-field RFID applications, given radiation pattern characteristics are expected. A fragment-type wire structure is quite suitable for these demands because uniform magnetic field distribution and given patterns could be generated through optimizing the fragmented wires in a designated electrically large area to obtain corresponding current distribution. In this article, the concept of a fragment-type structure as well as some design guidelines are reviewed and summarized. Then, two omnidirectional fragment-type wire antennas with different cell size and two directional fragment-type wire antennas are designed. Both simulation and experiment results show that there is no reading null within an electrically large near-field zone having a perimeter of four operating wavelengths at 915 MHz (i.e., 320 mm x 320 mm). The omnidirectional designs are promising in the applications of UHF near-field RFID tag detection in self-confined volumes, and the directional designs are potential in the systems of UHF near-field/far-field RFID.

Wideband high gain circularly polarized UHF RFID reader microstrip antenna and array

This paper presents a wideband and high gain circularly polarized ultra-high- frequency (UHF) radio frequency identification (RFID) reader microstrip antenna and array. Such antenna unit is composed of one main radiation patch and one parasitic radiation patch with air as the dielectric spacer. Two feeding lines connect to the main radiation patch with 90deg phase difference. Numerical optimizations and experimental demonstrations are performed to investigate the performances of the proposed antenna unit and good agreements are obtained. This antenna unit can cover the whole UHF band (860–960MHz) with gain of 9.7dBi. Then two antenna arrays of 1×4 and 2×2 based on previously demonstrated antenna unit are numerically investigated. The array performances, including the gain, beam scanning and low side-lobe are discussed. The obtained results in this paper indicate that the proposed antenna and array are suitable for the universal UHF RFID applications.

Planar Compact Square-Ring Tag Antenna With Circular Polarization for UHF RFID Applications

This paper describes a novel compact design of a planar circularly polarized (CP) tag antenna for use in a ultrahigh frequency (UHF) radio frequency identification (RFID) system. Introducing the meander strip into the right-arm of the square-ring structure enables the measured half-power bandwidth of the proposed CP tag antenna to exceed 100 MHz (860-960 MHz), which includes the entire operating bandwidth of the global UHF RFID system. A 3-dB axial-ratio bandwidth of approximately 36 MHz (902-938 MHz) can be obtained, which is suitable for American (902-928 MHz), European (918-926 MHz), and Taiwanese UHF RFID (922-928 MHz) applications. Since the overall antenna dimensions are only 54 × 54 mm 2 , the proposed tag antenna can be operated with a size that is 64% smaller than that of the tag antennas attached on the safety glass. With a bidirectional reading pattern, the measured reading distance is about 8.3 m. Favorable tag sensitivity is obtained across the desired frequency band.

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.

Selectable sectoral antenna array using a quadruple feeding network for item‐level tagging in UHF RFID applications

ABSTRACTFor avoiding a dead zone where the tag cannot be detected in the ultrahigh‐frequency (UHF) radio frequency identification (RFID), a SELECTABLE SECTORAL ANTENNA ARRAY USING a QUADRUPLE FEEDING NETWORK FOR ITEM‐LEVEL TAGGING IN UHF RFID APPLICATIONS is presented. The proposed antenna array consists of a 2 × 2 circular polarized quadrifilar spiral antenna array and a quadruple feeding network for multiple beams. It generates single, dual, and quad beams with a hemispheric coverage by a beam switching, and its maximum gain and 3 dB beamwidth are approximately 7.8 dBic and 60°, respectively. Compared with the conventional antennas, the proposed antenna array provides the improved tag identification with the dead zone avoidance in the reading range. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1523–1526, 2015

A circular patch antenna with parasitic element for UHF RFID applications

This article initially proposes a directly-fed circular patch antenna with L-shaped ground plane for Radio Frequency Identification (RFID) applications in the 900 MHz (902−928 MHz) ultrahigh frequency (UHF) band. To achieve circularly polarized (CP) radiation, two arc-shaped notches are loaded into the main patch. To enhance the CP bandwidth so that the proposed antenna can also cover the UHF RFID band for Europe (866−869 MHz), a parasitic element is printed besides the main patch. Experimental measurements show that the 10-dB return loss bandwidth of the proposed antenna was 30.95% (833−1138 MHz) and its corresponding 3-dB axial ratio bandwidth was 8.95% (865−946 MHz). Good gain and radiation efficiency of more than 7 dBic and 90%, respectively, were also exhibited across the two desired UHF RFID bands. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:681–687, 2015.

A Novel Circularly Polarized Antenna With Coin-Shaped Patches and a Ring-Shaped Strip for Worldwide UHF RFID Applications

A circularly polarized radio frequency identification (RFID) reader antenna is presented for worldwide ultra- high frequency (UHF) applications. The antenna is composed of two coin-shaped patches, a ring-shaped strip, and a suspended feeding strip with open-circuited termination. The measurements show that the antenna has an impedance bandwidth ( ${ S}_{11} ) of 22.4% (768–962 MHz) and a stable gain with a peak value of 9.8 dBic. Moreover, it is immune to polarization mismatch with a 3-dB axial-ratio (AR) bandwidth of 15.9% (816–957 MHz) and a 3-dB AR beamwidth of more than 66 $^\circ $ . The proposed antenna can be a candidate for universal RFID readers at the UHF band of 840–955 MHz. Due to the fact that the square holes in the center of the coin-shaped patches can embed one additional small antenna, the proposed antenna has the potential to be a dual- or tri-band combined RFID reader antenna, spanning both the conventional UHF and the ISM band of 2.45 or 5.8 GHz.

Equilateral triangular patch antenna for UHF RFID applications

This article proposes an equilateral triangule-shaped patch antenna for radio frequency identification (RFID) applications in the 900 MHz (902–928 MHz) ultra high frequency (UHF) band. To achieve optimal impedance matching and 10-dB operating bandwidth at the desired band, the L-shaped probe-feed technique was used as the feeding structure of the proposed antenna. Furthermore, a near semicircular notch was also loaded into the patch so that good circularly polarized (CP) radiation can be generated from the proposed patch antenna. By simply shifting the position or radius of this notch, the CP frequency can be varied with ease. Here, 10-dB impedance bandwidth and 3-dB axial ratio bandwidth of 25 and 3% were achieved. Furthermore, stable gain variation of approximately 6 dBi was also exhibited across the RFID UHF band. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:580–586, 2014.

Complementary metal-oxide-semiconductor humidity sensor design for passive ultra-high frequency radio-frequency identification application

This paper presents a low-cost low-power humidity sensor for applications of ultra-high frequency radio frequency identification sensing tag. The humidity sensor element, based on standard SMIC 0.35 μm complementary metal-oxide-semiconductor technology, utilizes polyimide as sensing material and fabricates the interdigitated electrodes in top metal layer without any further post-processing. The humidity sensor interface, based on phase-locked loop theory, employs fully-digital architecture and achieves direct capacitance-to-digital conversion, which allows the supply voltage to be close to threshold voltage. The measurements at 25 ℃ show that the proposed humidity sensor achieves a sensitivity of 36.5 fF%RH, maximum hysteresis error of 7%, response time of 20 ms, and 2.1 μW power dissipation at 0.6 V supply voltage.

Wearable Quarter-Wave Folded Microstrip Antenna for Passive UHF RFID Applications

A wearable low-profile inset-fed quarter-wave folded microstrip patch antenna for noninvasive activity monitoring of elderly is presented. The proposed antenna is embedded with a sensor-enabled passive radio-frequency identification (RFID) tag operating in the ultra-high frequency (UHF) industrial-scientific-medical (ISM) band around 900 MHz. The device exhibits a low and narrow profile based on a planar folded quarter-wave length patch structure and is integrated on a flexible substrate to maximise comfort to the wearer. An extended ground plane made from silver fabric successfully minimises the impact of the human body on the antenna performance. Measurements on a prototype demonstrate a reflection coefficient (S11) of −30 dB at resonance and a −10 dB bandwidth from 920 MHz to 926 MHz. Simulation results predict a maximum gain of 2.8 dBi. This is confirmed by tag measurements where a 4-meter read range is achieved using a transmit power of 30 dBm, for the case where the passive wearable tag antenna is mounted on a body in a practical setting. This represents an almost 40% increase in read range over an existing dipole antenna placed over a 10 mm isolator layer on a human subject.