UHF RFID antenna tag design and analysis for antenna miniaturization

This paper proposes four designs of UHF RFID antenna tag with two different radiating element, copper and aluminum, for antenna miniaturization. The main contribution of this work is the unique design that involves a meander line traced in a variety shape of a bowtie antenna. The UHF RFID band is achieved by reshaping a 900 MHz straight line dipole antenna into the form of a bowtie, thus reducing the size of the antenna significantly while maintaining the operating frequency. The effectiveness of the method is tested in multiple steps. First, the antenna tag designs are run through CST software simulations and optimized to achieve desired outcome. Next, the designs are transferred to Silhouette Studio software to be fabricated using a cutting machine, and finally measured using a vector network analyzer. The comparison between the measurement result of the reflection coefficient and the radiation pattern to their respective simulation results shows that they have a good agreement between each other. With further research and improvements, the size of the antenna tag could be further reduced while maintaining or even improving the performance of the antenna tag

Performance assessment of a novel miniaturized RFID tag for inventorying and tracking metallic tools

This contribution proposes a novel radio frequency identification tag antenna operating in the EU UHF band (865-868 MHz). Miniaturization techniques have been used to achieve a reduced volume (20 × 2.56 × 3 mm 3 ) in order to make it suitable for labeling metallic tools. Simulations are used to assess the tag performance when operating on tools of different sizes. These simulations are validated through measurements in a reference scenario (anechoic chamber). Finally, a real scenario (tool hanging board) is considered in order to evaluate tag performance when interacting with other tags and tools

Design of a small-size, low-profile, and low-cost normal-mode helical antenna for UHF RFID wristbands

Emerging RFID applications in the UHF band in some cases require very specific antenna solutions. This letter considers the identification and tracking of patients inside hospital facilities using wristbands, which impose strict tag size and cost limitations. We propose a solution for passive tags based on a normal-mode helical antenna as an alternative to bulky and/or expensive solutions that can be found in the literature. The robustness of the resulting wristband will be assessed in a particular implementation by measuring the maximum read range for a variety of subjects with different physical constitutions

Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags: the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique

Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices demonstrate performances which achieve wireless communication requirements having a forward transmission scattering parameter, S21, depth greater than ?20 dB at 13 GHz. Printed and plasma sintered RFID tags on transfer paper, which are capable of being mounted on skin, improved read distances compared to previously reported single layer transfer RFID tags fabricated by conventional thermal sintering

A Miniaturized Patch Antenna Designed and Manufactured Using Slot's Technique for RFID UHF Mobile Applications

In this research work, a novel compact antenna with rectangular slots is presented for radio frequency identification (RFID) handled applications in the ultrahigh frequency (UHF) band that can be manufactured and integrated into RFID readers without difficult. A prototype demonstrating the aforementioned features was constructed and measured. The proposed antenna is fed by 50-Ω coaxial cable and printed on a 1.6mm thick FR4 substrate which has a small size and occupies a volume of 68×66 ×1.6mm3. The patch, the feed-line and ground plane are made of PEC (Perfect Electric Conductor) with a thickness of 0.035 mm. Measured results indicate that the proposed antenna has a good impedance matching characteristic ranging from 889 to 939MHz, which covers the USA RFID-band (902–928MHz), the Chinese RFID-operating-band (920–924.5MHz), and the Korea and Japan RFID-band (917–923.5MHz). These results were achieved by the insertion of slots in the compact structure of the antenna. The electromagnetic simulators HFSS (High Frequency structure simulator) and CST (Computer Simulation Technology) microwave studio were used for the design, modeling and simulation of the antenna. The focus of the study of our antenna was on the parameters of return loss, bandwidth, Voltage Standing Wave Ratio (VSWR), input impedance and gain

Target Read Operation of Passive Ultra High Frequency RFID Tag in a Multiple Tags Environment

Passive ultra-high frequency (UHF) radio frequency Identification (RFID) has emerged as a promising solution for many industrial applications. Passive UHF systems are relatively inexpensive to implement and monitor, as no line of sight is required for the communication. There are several advantages to using a passive RFID system. For example, no internal power source is required to activate the tags, and lower labor costs and efficient multitasking operations are expected in a long term scenario. However, due to factors such as tag-to-tag interference and inaccurate localization, RFID tags that are closely spaced together are difficult to detect and program accurately with unique identifiers. This thesis investigates two main ways to enable and improve multi-tag operations: physical tag placement and design of the near-field RFID reader antenna. First, several factors that affect the ability to encode a specific tag with unique information in the presence of other tags are investigated, such as reader power level, tag-to-antenna distance, tag-to-tag distance and tag orientation. A Full Factorial Design is carried out to study the effects of each of the factors and factor interactions. Results suggest a preliminary minimum tag-to-tag spacing which enables the maximum number of tagged items to be uniquely encoded without interference. In order to individually read each tag in a multi-tag form, an experimental device is built to enable controlled movement and positioning of the reader’s antenna to the location of each of the tags. The experimental device is also designed to test other mechanical means of isolating the tags, such as shielding and mechanical isolation of the tagged media. Furthermore, to test a second method of improving the efficacy of programming tags uniquely in a multi-tag environment, the reader’s antenna is redesigned to confine the electromagnetic field distribution to reduce the probability of activating non-targeted tags in the surrounding. Using the commercial software package ANSYS High Frequency Structural Solver (HFSS), the coupling interaction between the reader’s antenna and RFID tags was simulated to investigate the relative voltage induced in the target tag relative to each of the proximal tags. The new antenna is then fabricated and validated with the simulation results. With a better antenna design and ideals tag placement, the read operation of multiple tags can be improved and made more reliable. These findings can potentially expedite the process of field programming in item-level tagging and increase the throughput rate of unique tag encoding

2-SR-based electrically small antenna for RFID applications

In this work, the 2-turn spiral resonator (2-SR) is proposed as an electrically small antenna for passive radio frequency identification (RFID) tags at the European ultra-high frequency (UHF) band. The radiation properties are studied in order to explore the viability of the 2-SR applied to tag antenna design. Based on analytical calculations, the radiation pattern is found to provide a cancelation of the radiation nulls. This results in a mitigation of the blind spots in the read range, which are present in typical UHF-RFID tags as an undesired feature. As a proof of concept, a passive tag of size 35 mm × 40 mm (λ₀/10 × λ₀/9) based on the 2-SR antenna is designed and fabricated. Good radiation efficiency (75 %) and a quasi-isotropic radiation pattern are obtained. The experimental tag read range for different directions is in good agreement with the simulation results. The measured read range exhibits maximum and minimum values of 6.7 and 3.5 m, respectively