Circularly Polarized Tag Antenna Research Articles

Design of 2.45GHz Circularly Polarized Tag Antenna

This paper presents the design and development of a circularly polarized (CP) tag antenna to overcome the polarization mismatch between the reader antenna and the tag antenna in RFID systems. This CP antenna is designed at 2.4 GHz for radio frequency identification (RFID) applications. It consists of a simple square loop loaded with an open gap, two feeding strips, and a matching stub. The antenna is fabricated on an FR4 substrate with a dielectric constant of 4.4, a dielectric loss tangent of 0.02, and a thickness of 0.8mm. In order to achieve conjugate matching between the circular tag antenna and the tag chip, the technique of loading a matching short line on the tag chip was used. Additionally, the radiation of circular polarization (CP) was achieved by placing an open gap and two feeding strips on the square loop. Through electromagnetic simulation analysis, the antenna performance is evaluated. The reflection coefficient (S11) at 2.45 GHz is measured to be - 17.16db, indicating good impedance matching. The 3 dB axial ratio bandwidth is 0.19 GHz (7.7%), covering the frequency range of 2.34 GHz to 2.53 GHz. The 10db power reflection bandwidth is approximately 8.9% (2.33 GHz to 2.55 GHz), ensuring broad operational bandwidth. The antenna also exhibits a favorable antenna gain of 2.29dBi. This study successfully demonstrates the design and performance evaluation of a CP tag antenna for RFID applications

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) < 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.

Planar circularly polarized tag antenna with compact operation for UHF RFID application

A novel compact design of planar circularly polarized (CP) tag antenna for UHF RFID system is proposed. By introducing the Y-shaped slit as the feed structure, the measured half-power bandwidth of the proposed CP tag antenna can be more than 135 MHz (860–1000 MHz), which includes the entire operating bandwidth for worldwide UHF RFID system. The obtained 3 dB axial-ratio (AR) bandwidth can be about 10 MHz suitable for Taiwan UHF RFID applications. The proposed tag antenna reduces the antenna size by at least 30% since the antenna size is only 40 × 40 × π mm2. The simulated peak gain and antenna efficiency are approximately 0.4 dBic and 91% for Taiwan UHF RFID band. Meanwhile, with omnidirectional reading pattern, the measured reading distance is about 7.2 m. Good tag sensitivity was obtained across the desired frequency band.

Design of a Circularly Polarized Tag Antenna for Increased Reading Range

We introduce a novel circularly polarized tag antenna, consisting of a truncated patch, a shorting plate, and a ground plane, to increase the reading range while remaining in compliance with EIRP regulations. The reading range of the proposed tag is twice that of linearly polarized tags, due to the decreased polarization mismatch between the reader and tag antennas. An additional parasitic patch is loaded onto the structure to boost the reading range in the UHF RFID band. As a result, an average reading range of 8 m is achieved between 860 MHz and 960 MHz, compared to a range of about 3 m with conventional dipole tags.