Tag Antenna Performance Research Articles

Effect of Stitch Structure on the Reading Performance of Fabric-Based Embroidered UHF RFID Tags

As the demand for low-cost rapid preparation techniques for RFID (Radio Frequency Identification) fabric tags is increasing, embroidery technologists have attempted to fabricate tag antennas. However, the effects of stitch structures on the performance of tag antennas have rarely been studied. Since the structure of an embroidered stitch is related to the embroidering process parameters and embroidery thread, this study chose a common stitch trace type to prepare two sets of UHF RFID tag antennae by changing the embroidery thread structure and stitch length, and then the electrical and gain properties of these antennas were analyzed. And again, the reading performance of the corresponding tag was evaluated. The results showed that the antennas embroidered with copper/PET wrapped yarns have higher energy transfer efficiency than those with single copper wire yarns. When the stitch length increases from 0.9 to 5 mm, the read range of the embroidered tag firstly increases and then decreases, due to the large embroidering process deviation of the tag antenna geometry, and the optimal stitch length for the read range is 1.7 mm, where the read range is 12.95 m. When the stitch length is 5 mm, the read range is minimum – 9.56 m. In summary, this study determined the embroidered thread structure and the process design of the stitch length in terms of the performance of a fabric-based embroidery antenna for an RFID tag as well as the read range.

Omega-Shaped Tag Antenna with Inductively-Coupled Feeding Using U-Shaped Stepped-Impedance Resonators for RFID Applications

This study proposes a new omega-shaped tag antenna with inductively-coupled feeding (ICF) using U-shaped stepped- impedance resonators (SIRs). It aims at improving the performance of the tag antennas for Radio Frequency Identification (RFID) applications. The radiating body of the antenna is fed using two mirroring symmetrical U-shaped SIRs. This antenna is a simpler alternative for the existing antennas that match the impedance of the antenna to the chip impedance effectively applying varied reinforcement of the equivalent inductance of the radiating structure. In addition to the use of an omega-shaped structure, the proposed feeding technique boosts performance of the antenna impedance, dimensions, and peak gain. The measured size of the antenna was 50×55.55×1.6 mm3. It attains a peak gain of 1.8 dBi and radiation efficiency higher than 85% at its operating frequency. The experimental results revealed that this tag antenna has the characteristic of good impedance matching within the frequency range of 900-940 MHz, corresponding to a better power reflection coefficient of -3 dB. Comparison between the measured and simulated results verified that the proposed feeding method is capable to improve overall performance of RFID tag antennas.

Design of UHF Tag Antenna Based on Internet of Things

This paper presents a detailed study of UHF RFID system on tag antenna design and performance measure methods based on antenna design knowledge and electromagnetic theory. The paper analyzes the characteristics of UHF tag antenna. The paper provides the compact UHF antenna that covers 840MHz∼965MHz. The impedance of the antenna is easy to adjust. The tag antenna has a good performance which satisfies the design requirements. The paper studies the effect of the metallic ground on the tag antenna performance and designs a low-profile anti-metal UHF tag antenna. An antenna with a pair of F-slots is proposed. The antenna can achieve the good complex impedance matching between the antenna and chip. The simulation results show the anti-metal antenna has good working bandwidth from 840MHz to 965MHz and return loss S11<-10dB.

A novel reverse design method of tag antenna based on image analysis

Since the working efficiency of the entire radio frequency identification system depends on the performance of the radio frequency identification tag antenna, the research and design of the tag antenna have received attention, especially for radio frequency identification tags applied to special scenes. We mainly studied the effect of antenna bending on the performance of ultra-high frequency radio frequency identification systems, and combined the bent antenna with the impedance matching loop to achieve impedance matching between the chip and the antenna in the ultra-high frequency band. We analyzed the variation of tag antenna performance with antenna parameters by the simulation software High Frequency Structure Simulator (HFSS). At the same time, we propose a novel antenna reverse design method. Through the analysis of the antenna-specific absorption rate image, the antenna performance intensity is visually reflected. According to the image analysis result, the antenna parameters are corrected to improve the antenna matching performance. This design method is simpler and faster than other methods.

A novel compact circularly polarized tag antenna with differential‐RFIC for EU UHF RFID applications

AbstractIn this paper, a novel compact ultra‐high frequency (UHF) tag antenna for radio frequency identification is presented. This tag uses the Monza‐X from Impinj as a differential radio frequency integrated circuit. A wideband circular polarization was achieved. The frequency range covered for an axial ratio (AR) &lt; 3 dB is from 830 to 903 MHz. The designed antenna is simulated by using the electromagnetic software ansys high frequency structure simulator. The tag antenna is printed on 50 × 50 mm2 of Roger 4350B substrate with a dielectric constant (Ԑr) of 3.66 and thickness of 1.52 mm. The manufactured tag antenna performance has been tested by measuring the reading distance. The measurement results show good values of reading range (RR) especially in the EU Radio Frequency IDentification band. The tag has a maximum RR of about 13.3 m at 865 MHz with an Effective Isotropic Radiated Power of 2 W.

UHR RFID ring resonator-based tag antenna with photonic bandgap structure for metallic objects

Several recent works highlighted that metamaterial-based antennas are capable to function similar to large printed antennas. This paper presents a novel split-ring resonator-based UHF RFID tag antenna with photonic bandgap structure on metallic objects for high gain, which consists of two symmetrical C-shaped resonators with outer strip lines to feed split-ring resonator structure through implementing an inductively coupled feed approach placed on the top surface of Polytetrafluoroethylene substrate. The simulation results were verified by the presented method via enhancing the performance of tag antennas for metallic object.

A compact implantable RFID tag antenna dedicated to wireless health care

Implantable tag antennas are an integral component of contemporary pervasive patient monitoring setups envisioned to reduce the medical errors and improve the quality of health care facilities. These tags, embedded into the human body, transmit critical patient information to the external equipment via a wireless communication link. This research article presents an implantable compact folded dipole antenna of size 10 mm × 15 mm × 2 mm, designed to operate in the industrial-scientific-medical band (2.4-2.48GHz). A three-layered phantom representing the human arm is used to evaluate the subcutaneous antenna performance. The tag antenna embedded in the middle of the fat layer offers a maximum gain of −16.3 dBi. The tag antenna performance as a function of implant position and phantom dimensions is analyzed. Link budget calculations show that with the achieved antenna gain the link power exceeds the required power by 38.37 dBm, and hence wireless communication is viable.

U-Shaped Inductively Coupled Feed Radio Frequency Identification Tag Antennas for Gain Enhancement

An inductively coupled feed novel technique is proposed to enhance the performance of radio frequency identification tag antennas. The applied feeding concept is comprised of two opposing symmetrical U-shaped structures to feed a radiating body. It is a simple alternative to effectively match the antenna impedance with the chip impedance from the flexible augmentation of equivalent inductance to the radiating body. The proposed feeding method offers better expectation of performance among antenna size, impedance, and gain at the size of 50 × 70 × 1.6 mm3. The peak gain of the proposed tag antenna is 2.5 dBi at its operating frequency, which is higher among conventional tag antennas. Measured results indicated that this tag antenna has a good impedance matching characteristic at 904–937 MHz (power reflection coefficient lower than −3 dB). The comparison between the simulation and measurement results verified the proposed technique's capability to improve overall performance of the tag antennas.

Radiation Efficiency Measurement Method for Passive UHF RFID Dipole Tag Antennas

Concurrently with the continuously developing radio frequency identification (RFID) technology, new types of tag antenna materials and structures are emerging to fulfill the requirements encountered within the new application areas. In this work, a radiation efficiency measurement method is developed and verified for passive ultra-high frequency (UHF) RFID dipole tag antennas. In addition, the measurement method is applied to measure the radiation efficiency of sewed dipole tag antennas for wearable body-centric wireless communication applications. The acquired information from measurements can be used to characterize tag antenna material structures losses and to further both improve and optimize tag antenna performance and reliability.

Effects of Sewing Pattern on the Performance of Embroidered Dipole-Type RFID Tag Antennas

Embroidered tag antennas can be used in on-body applications, such as access control, human monitoring, and sensor tag antennas. The objective of this letter is to investigate the performance of dipole-type tag antennas sewed with different thread densities and with two different sewing patterns. This letter shows that the performance of sewed dipole-type tag antennas improves if the sewing pattern consists of sewed lines along the direction of current flow in the antenna. The sewed simple dipole, which consists of sewed lines along the length of the dipole, achieved up to 7.5 m read range in free space, which is comparable to the performance of the corresponding copper dipole.

Curved Dual - Band Dielectric Resonator Tag Antenna for RFID Applications

This paper presents a new application of dielectric resonator antenna in radio frequency identification system. A curved dual-band dielectric resonator antenna for RFID applications is proposed. The tag antenna is designed to operate at 2.45 GHz (2.25– 2.55 GHz) and 5.8 GHz (5.65– 5.95 GHz) bands. The radiation characteristics of the tag antenna in free space are investigated. The radar cross sections under different loads are obtained. The effect of curvature on the tag antenna performance is explained. Two examples are considered. In the first example, the tag antenna is mounted on cylindrical bottle filled with the Polyethylene material. The effect of the object properties on the radiation characteristics and the radar cross section is investigated. In the second example, the tag antenna is mounted on spherical bottle filled with the Polyethylene material. The radiation and backscattering characteristics are calculated. The Finite Element Method (FEM) is used for simulation and the Finite Integration Technique (FIT) is used to verify the simulated results.

Inkjet-printed passive UHF RFID tags: review and performance evaluation

In this paper, the performance and the feasibility of inkjet-printed dipole RFID tag antennas are experimentally studied in the implementation of identifying objects with different electromagnetic properties. To estimate the performance quality, we compare our results to those obtained using traditional etched copper dipole tag antennas. We first examine the performance characteristics, i.e. the read range and the radiation patterns, of tags in free space. Then we attach the tags directly to target objects and compare the optimum performance on target objects to that of the tag in free space. The obtained results provide information about the behaviour of inkjet-printed tag antennas on different objects. This information can be used to optimize the inkjet-printed tag antenna performance for use on objects with different characteristics.

Characterization of UHF RFID tags fabricated directly on convex surfaces by pad printing

The possibility of pad printing in RFID tag antenna manufacturing is investigated. Passive UHF RFID tags were printed on flat and on convex surfaces with two different polymer thick-film silver inks. The effect of the ink and substrate material properties on tag antenna performance was examined. The goal was to provide information which is needed in adapting the pad-printing technique in RFID tag manufacture. The results show that pad printing is suitable for tag manufacturing on flat and on convex surfaces. The curvature of the substrate did not significantly affect the tag performance. It was more important to take into consideration other substrate properties, ink characteristics, morphology, and printing parameters. The best practice is to take these matters into consideration in the initial tag design process to ensure proper tag performance at the desired frequency.

Geometric and Compaction Dependence of Printed Polymer-Based RFID Tag Antenna Performance

Radio frequency identification (RFID) tags with printed antennas are lower in cost but have lower performance than those with metal antennas. Printed antennas can replace metal ones if the performance is increased without raising cost. The performance of printed antennas can be increased if the series resistance in the antennas is lowered. The resistance is dependent on the line thickness and the resistivity of the conductive ink. Printed antennas with different line thicknesses were fabricated to investigate the effect of compaction and thickness on the resistance. The resistance of the printed antenna coils decreased by more than 40% after compaction, while the inductance and the parasitic capacitance were unchanged. RFIDs with compacted printed antennas were found to have significantly increased read range. RFIDs with thick printed antennas were fabricated and tested. These RFIDs were shown to have read ranges comparable to the RFIDs with copper wire antennas. Moreover, a geometry-independent plateau for the read range was found. The presence of a plateau is valuable for thick-line printed antenna since the plateau will enable the usage of low precision printing techniques to lower tag fabrication cost.

UHF 대역 RFID 태그 안테나의 RCS(Radar Cross Sections) 분석 및 측정

In the RFID system, one of the important criteria of tag antenna performance is the detection distance. The most important factor determining the detection distance of the tag antenna is the Radar Cross Sections(RCS). In this paper, we propose a method to simply measure the RCS of the RFID tag antenna using two reader antennas(Tx and Rx) and a network analyzer. We estimate RCS` from the RCS equation based on the measured using the network analyzer. We compare the measured values with the calculated values and the simulated values using EM simulator. The used tag antennas are two kinds of dipole-type, metal-type, and an inductively-coupled type ones. In case of the dipole type, the measured, simulated and calculated values of the RCS are almost the same. In case of other types, we obtain the measured RCS values with a difference of about 3 dB.

Effects of size and shape of metallic objects on performance of passive radio frequency identification

Passive ultra high frequency (UHF) spectrum radio frequency identification (RFID) systems have numerous applications. Continuous research and development of RFID systems is carried out to study solutions for different challenging cases of identification. Metallic objects set challenges for identification due to the behavior of electromagnetic waves on conductive boundaries. Therefore, novel tag designs have been developed for identification of metallic objects. This article presents a performance comparison of two different metal-mountable tag antennas, which are printed inverted-F antenna (IFA) and microstrip patch antenna with photonic band gap (PBG) ground plane and with regular ground plane. The effects of size and shape of metallic objects on tag antenna performance are studied with read range measurements and compared between the tag antenna types.

Effects of metallic plate size on the performance of microstrip patch-type tag antennas for passive RFID

Metallic objects are challenging for passive ultra high frequency (UHF) spectrum radio frequency identification (RFID) systems due to the effects of conductive materials on tag antenna performance. In this letter, we analyze the effects of metallic plate size on the performance of microstrip patch-type tag antennas. Microstrip patch antennas with regular ground plane and electromagnetic band gap (EBG) ground plane are studied attached to two differently sized metallic plates. Analysis is based on finite element method (FEM) simulations and practical read-range measurements.