Physical relationship between resonant frequency and structure parameters of a normal mode helix dipole antenna for an ultra-high frequency radio frequency identification tag thread

Abstract

The thread-based ultra-high frequency radio frequency identification (UHF RFID) tag with a normal mode helix dipole antenna (NMHDA) shows great potential in anti-theft and implant wireless sensors; for the engineered and digitized design of the high-performance tag, it is necessary to know the physical relationship between the resonant frequency and structure parameters of the NMHDA. Previous work for the design of the NMHDA structure is based on the self-resonant principle, that is, zero port reactance, while the port impedance of the NMHDA in the UHF RFID tag thread at resonant frequency is ideally conjugate matching to the chip. Under the requirement of conjugate matching, this study built the physical relationship between the resonant frequency and structural parameters of the NMHDA (helical radius, helical pitch, and single arm length) by linking the chip impedance with the NMHDA impedance. Meanwhile, the reported equivalent impedance model of the NMHDA, consisted of a lumped inductor and a linear dipole antenna, was utilized and modified by considering the distributed capacitance deviation from the NMHDA geometry simplification as part of the lumped inductor. Finally, the physical relationship was put into practice for the design of an UHF RFID tag thread with expected resonant frequency, and the long reading range of the prototype (over 14 m) demonstrated the rationality of the modification. In addition, the discussion on the structure parameter of the NMHDA clarified the efficiency of our proposed method. Generally, the built physical relationship explicitly gives the physical effects of the structural parameters and provides a parametric method for the structure design of a NMHDA for the UHF RFID tag thread.

The influence of structure uniformity on resonant frequency of ultra-high frequency radio frequency identification tag thread With normal mode helix dipole antenna

“…In optimizing the NMHDA structure to obtain the expected resonant frequency of UHF RFID tag thread, previous work ignored the ununiform structure of NMHDA. 11 Obviously, this work indicates that the influence of structural uniformity on the resonant frequency cannot be ignored in the designing of NMHDA structure for UHF RFID tag thread as well as its manufacturing processes.…”

“…Helical pitch. According to the geometric size of the common UHF RFID tag thread with NMHDA, 10,11 the helical radius was set to 0.615 mm. The helical pitches were randomly generated by the normal distribution.…”

“…1. Furthermore, based on the geometric dimensions of prototype, 11 the NMHDA with the conductor radius of 0.045 mm, the single arm length of 43.0 mm, the helical radius of 0.615 mm, and the helical pitch of 1.0 mm was constructed as shown in Figure 3.

Figure 3.Geometric model: (a) Front view; (b) Left view; (c) Top view.

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The Interconnecting Process and Sensing Performance of Stretchable Hybrid Electronic Yarn for Body Temperature Monitoring

“…Two-component copper ICA was chosen as the conductive adhesive for interconnecting the thermistor and electronic wires in surface mount technology [ 13 , 17 ]. The NTC thermistor was securely positioned in a customized groove mold, with its two contactors connected to the enameled copper wires using a drop of DB2011, a two-component copper ICA.…”

“…Therefore, new interconnection structures and encapsulating methods need to be developed in order to improve the durability and maintain sensing accuracy for this kind of hybrid electronic yarn. Previous work has also shown that the helix structure is a common strategy for achieving the good stretchability of metal wire [ 13 , 14 , 15 ] while bonding technology with a conductive adhesive is a mature and applicable interconnection technology for producing printed flexible hybrid electronics [ 16 ]. In this way, the strategy combining the helix wire structure with bonding technology could potentially enable high mechanical durability and large-scale manufacturing for hybrid electronic yarn and then improve human motion flexibility, the working performance stability, and the service lifetime of smart garments or fabrics.…”