Passive RFID Tag Antenna Research Articles

A Novel Antenna Design of Compact HF and UHF Passive RFID Tags with Interconnected Structure for Energy Harvesting and Tracking Systems

We propose a new dual-band passive RFID tag antenna design by combining a rectangular spiral coil and patch-meander-line dipole with an interconnected structure. This design enables operation in high-frequency (HF) and ultra-high-frequency (UHF) RFID systems, suitable for energy harvesting and tracking applications. The simulations by the CST full-wave software demonstrate conjugate impedance matching between the tag antenna and two RFID tag chips. At 13.56 MHz (HF), the tag antenna exhibits an inductive reactance of 422.79 Ω, while at 922.5 MHz (UHF), it presents an impedance of 9.41+j174.96 Ω. The antenna generates a maximum magnetic field intensity of 0.5 A/m and omnidirectional electromagnetic fields with an antenna realized gain of -4.26 dBi at 922.5 MHz. We also analyze the impact of the tag antenna combination using numerical software. Furthermore, we fabricate a prototype tag antenna and validate its performance with RFID readers. The proposed tag antenna achieves the maximum read ranges of 11 cm and 6.9 m for the HF (13.56 MHz) and UHF (920-925 MHz) bands, respectively, accompanied by the energy harvesting of 1.48 volts at the HF band by the coupling magnetic field received by the HF antenna to the chip ST25DV04K at the output voltage pin.

Spiral resonator loaded S‐shaped folded dipole dual band UHF RFID tag antenna

AbstractA miniaturized UHF dual‐band passive RFID tag antenna operating in the 866‐869 and 950‐956 MHz bands is proposed. It consists of an S‐shaped Folded Dipole Antenna (FDA) resonating at 912 MHz, which is intermediary between the two required frequencies. To obtain dual‐band response perturbation method is employed. The electrical length of the FDA changes on loading a 2‐turn spiral resonator (2‐SR) to it. The 2‐SR splits the tag resonance at 912 MHz into two resonance frequencies (867 and 956 MHz). The proposed design is simulated using HFSS and then fabricated. Measured reflection coefficients at 867 and 956 MHz are −13.25 and −13.34 dB, respectively, exhibiting a 10 dB bandwidth of 11 MHz from 859 to 869 MHz and a 5 MHz 10 dB bandwidth from 953 to 957 MHz. Maximum read ranges of 5 m in 866‐869 MHz and 3.3 m in 950‐956 MHz band have been measured.

Dual-band RFID Tag Antenna Applicable for RF Power Harvester System

In this paper, a dual-band antenna is proposed for the RF power harvester system as well as RFID tag. The proposed antenna operates as the passive and active RFID tag antenna in the UHF and microwave band, respectively. In addition, to charge the battery of an active RFID tag in the microwave band, it harvest the RF signal for tagging from the passive RFID tag antenna in the UHF band. The proposed antenna operates in the UHF band (917~923.5 MHz) and microwave band (2.4~2.45 GHz). In order to obtain the dual-band operation, the dipole structure and meander parasitic elements are proposed as the and dipole antenna, respectively. The radiating dipole structure in the microwave band acts as the coupled feed for the meander parasitic elements in the UHF band. The impedance bandwidth (VSWR

Design of an Ultra-Compact UHF Passive RFID Tag Antenna for a Medical Sample Tube

In this letter, a small-sized ultra-high frequency (UHF) RFID tag antenna for a medical sample tube is proposed. The RFID tag antenna is designed and fabricated based on the circular loop antenna used in the UHF band (Korea standard, 917 MHz to 923.5 MHz). The tag antenna size is reduced using a circular meander stub. The antenna has a physical size of 8 mm, which is about λ/40 in electrical length. The proposed tag antenna is molded into a medical sample and multitag identification is performed.

Coupling-Feed Circularly Polarized RFID Tag Antenna Mountable on Metallic Surface

A square patch passive RFID tag antenna designed for UHF band is presented in this article. To achieve compact size and circular polarization (CP) radiation, the square patch is embedded with a cross slot, while an L-shaped open-end microstrip line linked to a tag-chip and terminated by a shorting pin is capacitively coupled to the patch. By selecting an appropriate length for the microstrip line and its coupling distance with the radiating element, easy control on the input impedance of the proposed tag antenna which leads to excellent impedance matching is achieved. The measured 10-dB return-loss bandwidth of the tag antenna is 50 MHz (904-954 MHz), while its 3-dB axial-ratio bandwidth is 6 MHz (922-928 MHz). Further experiment shows that the tag antenna can provide better reading range when mounted on a metallic surface.

A Passive RFID Tag Antenna Installed in a Recessed Cavity in a Metallic Platform

A passive RFID tag antenna in a recessed cavity in metallic objects such as vehicles, air craft, and metallic containers, and an impedance matching technique for this configuration are proposed. The proposed tag antenna can be considered as a cavity-backed antenna and it is comprised of a bowtie antenna installed in a recessed cubic volume in a large metallic object, and the input impedance of the bowtie antenna can be easily matched by adjusting the coupling effect between the tag antenna and the cavity. Main parameters affecting the coupling are the dimensions of the cavity and the location of the bowtie antenna inside the cavity. For more practical analysis of the impedance matching process, an equivalent-circuit model consisting of several lumped elements is introduced and each element is optimized using a genetic algorithm (GA). Experimental results show that the maximum reading distance of the proposed tag antenna with optimized dimensions can be improved about 3.2 times compared to a commercial RFID tag.

Broadband microstrip antenna with U and T slots for 2.45/2.41 GHz RFID tag

A novel single-layer passive RFID tag antenna for the resonant frequency 2.45/2.41 GHz using a square microstrip patch with a pair of U and T slots is proposed, which is suitable for attaching to metallic objects. The proposed antenna was fabricated with a thin copper layer printed on a thin lossy FR4 substrate for low-cost production. The dimensions of the proposed antenna are around 35×35 mm. The antenna shows near-linear phase characteristics, 250 MHz bandwidth under the condition of voltage standing-wave ratio less than 2 and it covers all RFID microwave bands. The gain of the proposed antenna is 2.0–2.2 dBi for worldwide RFID microwave bands. Half-power bandwidth is about 108°.

Broadband RFID tag antenna with quasi-isotropic radiation pattern

A passive RFID tag antenna in the UHF band using two bent dipoles and a modified double T-matching network is proposed. The antenna was fabricated with a thin copper layer printed on a 50 µm-thick PET substrate for low-cost production. The proposed antenna provided a quasi-isotropic radiation pattern and a fairly broad bandwidth S11<−10 dB, 8.5%) for conjugate-matching with a commercial tag chip. The efficiency of the antenna was about 90% in the operating frequency band. The measured readable range was between 170 –240 cm for an arbitrary rotation angle of the tag.