Design and modeling of embedded 13.56 MHz RFID antennas (original) (raw)

Effect of added resonators in RFID system at 13.56 MHz

IET Microwaves, Antennas & Propagation, 2018

In this study, a reader antenna including resonators is proposed to improve detection of a small moving tag in the case of tracking a radiofrequency identification (RFID) system. The near-field RFID technology is based on load modulation, the input impedance on the reader coil and the mutual inductance between the reader and tag coils are the main parameters for performing detection. They are calculated from the impedance matrix parameters. The added resonators change all the parameters of the impedance matrix consequently the input impedance and mutual inductance are also changed. In this study, analytical formulation defining the equivalent impedance matrix parameters is developed. These formulae are used to evaluate the performance of the proposed design according to the tag misalignment (lateral and angular). From the calculation and simulation results, a frequency shift in the equivalent input impedance is found. To avoid this problem, optimising the positioning of the resonators on the reader coil is performed. This study is confirmed by measures of RFID detection for a reader prototype (with and without resonators) and a small commercial tag. Both the surface and volume of detection of the small moving tag (lateral and angular misalignment) are improved by the principle of added resonators.

Development of compact inductive coupled meander line RFID tag for near-field applications

International Journal of Microwave and Wireless Technologies, 2016

The development of compact radio frequency identification (RFID) tag is the key requirement for wireless tracking of precious small size goods/packages in transport. A design of compact meander line tag antenna having inductive coupling feed is presented for RFID system operating at ultra high frequency band of865–867 MHz. The size of the proposed tag antenna is43 mm × 10 mm, and is designed using Higgs 4 IC chip (made Alien Technology, USA) having impedance of20.55− j191.45 Ωat centre frequency866 MHz.The antenna characteristics such as impedance, radiation pattern, bandwidth, and effect of ground on gain and tag size are analyzed and found to closely match with the simulated values. The observed value of reading range varies from87.5 to 35 cmsdepending on mounting on non-metal and metal packages, respectively.

Impedance matching for RFID tag antennas

2011

Passive UHF RFID tag consists of a microchip attached to an antenna. Proper impedance match between the antenna and the chip is crucial in RFID tag design. It directly influences RFID tag performance characteristics such as the read range. It is known that an RFID microchip is a nonlinear load whose complex impedance varies with the frequency and the input power. We investigate the effect of using constant chip impedance while designing UHF RFID tags for specific frequencies. Commercial Avery Dennison AD-220 tag was simulated by Ansoft HFSS software. Afterwards, the read range of the tag was obtained numerically and compared with the measured values using the Voyantic Tagformance RFID measurements system.

Energy Scavenging for Inductively Coupled Passive RFID Systems

IEEE Transactions on Instrumentation and Measurement, 2007

Deployment of passive radio-frequency identification (RFID) systems or RFID-enhanced sensor networks requires good understanding of the energy scavenging principles. This paper focuses on the energy scavenging design considerations of inductively coupled passive HF RFID systems. The theoretical estimation of the power by a loop antenna is derived, and the effect of the design parameters on the harvested power is investigated. It is shown that the power delivery performance is largely affected by the tag load at the reader. An adaptive matching circuit at the reader is proposed for achieving optimum power delivery performance when the reader has a variable load. Experimental studies confirm analytical derivations.

A High-Gain Passive UHF-RFID Tag with Increased Read Range

Sensors, 2016

In this work, a passive ultra-high frequency radio-frequency identification UHF-RFID tag based on a 1.25 wavelengths thin dipole antenna is presented for the first time. The length of the antenna is properly chosen in order to maximize the tag read range, while maintaining a reasonable tag size and radiation pattern. The antenna is matched to the RFID chip by means of a very simple matching network based on a shunt inductance. A tag prototype, based on the Alien Higgs-3 chip, is designed and fabricated. The overall dimensions are 400 mmˆ14.6 mm, but the tag width for most of its length is delimited by the wire diameter (0.8 mm). The measured read range exhibits a maximum value of 17.5 m at the 902-928 MHz frequency band. This represents an important improvement over state-of-the-art passive UHF-RFID tags.

RFID tag antenna with a meandered dipole and inductively coupled feed

This paper presents tag antennas with an inductively coupled feed structure for the RFID application in the UHF band. The designed antennas consist of the rectangular loop for feeding and meandered dipole. We estimate the maximum bandwidth of the designed antenna using the approximate calculation and the calculated results are verified by measuring the read range of the tag antennas as a function of frequency. The read range of the designed RFID tag is approximately from 2.5m to 4m in air.

Design and Experimental Evaluation of Modified Square Loop Feeding for UHF RFID Tags

PLOS ONE, 2015

This paper addresses the performance evaluation of a modified square loop antenna design for UHF RFID applications that is excited through a narrow feed line connected to a square loop, an impedance matching network. The square loop dimensions are modified to reach a conjugate impedance matching. A gap is fixed between the feed-lines to link the chip. To achieve impedance matching, the structures of the feed-line are optimized accordingly. In addition, the antenna consists of a straightforward geometry. An 11.9-meter maximum read range is achieved using a compact size of 80 × 44 mm 2 and 3.2 W for the effective isotropic radiated power. Additional findings reveal that the proposed tag antenna is able to provide a stable resonance response in the near field of a large metallic surface.

Electromagnetic analysis of UHF near-field RFID tag antenna

General Assembly and Scientific Symposium, 2011

In this paper, the performance of Near-Field UHF RFID systems is investigated by means of electromagnetic analyses. A novel antenna is presented for ultra high frequency (UHF) near-field radio frequency identification (RFID) applications. The reactance component of tag antenna considered chip impedance (-193j) is conjugated and matched for maximum power transmission. The antenna is fabricated by using Polyester (PET) dielectric