Search Results (3)

The aim of this paper is to demonstrate progress in textronic UHF RFID transponder (RFIDtex tag) technology. The fundamental idea behind the RFIDtex tag design involves galvanic separation between circuits of the sewn antenna and the chip, which are electromagnetically coupled through a system of inductive loops. To advance the development of this concept, it is crucial to detect factors affecting the performance of the transponders. To achieve this goal, a mathematical model of the textronic UHF RFID transponder was developed. It involves relationships that describe the impedance of each element, the mutual inductance of the loops, and the chip voltage, and it enables the exploration of the influence of these variables on general parameters such as impedance matching and read range. Various analytical and numerical approaches were considered to obtain the value of the mutual inductance of the loops. The dimensions and geometry of the antenna, as well as the matching circuit in the microelectronic module, were taken into account. Based on the mathematical model, it was determined that mutual inductance strongly affects the chip voltage for frequencies higher than 800 MHz. The calculations from the mathematical model were compared with numerical simulations. Experimental studies were also conducted to investigate how the transponder performance is affected by either the distance between the centers of the loops or the conductivity of the threads used to embroider the antenna. The measurement results allowed us to conclude that even small imperfections in the manufacturing of the transponder, which slightly increase the vertical or horizontal distance between the centers of the loops, cause a dramatic decrease in the mutual inductance and coupling coefficient, significantly impacting the transponder’s performance. Full article

The idea of novel antennas and matching circuits, developed for radio frequency identification (RFID) passive transponders, and made on textile substrates, is presented in this paper. By manufacturing an RFID transponder by the means used in every clothing factory, we developed the concept of RFIDtex tags, which, as textronic devices, make a new significant contribution to the Internet of Textile Things (IoTT). The main feature of the device consists of the use of an uncommon inductively coupled system as the antenna feed element. The antenna is sewn/embroidered with a conductive thread, and the microelectronic module with an RFID chip is made in the form of a bead, using standard electronic technology. Finally, the construction of the RFIDtex tag is developed for easy implementation in production lines in the garment industry. The proposed inductive coupling scheme has not been considered anywhere, so far. The developed transponder is dedicated to operating in RFID systems of the ultra-high frequency band (UHF). The numerical calculations confirmed by the experimental results clearly indicate that the proposed coupling system between the antenna and the microelectronic module works properly and the RFIDtex device can operate correctly within a distance of several meters. The proposed design is based on the authors’ patent on the textronic RFID transponder (patent no PL 231291 B1). Full article

In order to respond the growing interest towards radio frequency identification textile transponders, the authors propose a new approach to design radio frequency identification (RFID) devices by introducing the RFIDtex concept. The coupling system of inductive loops is implemented in the textronic structure with the RFID interface in order to split the transponder into two independently manufactured components. Then both modules can be easily integrated into the RFIDtex tag. The presented simulation and measurement results prove the concept of manufacturing a relatively small antenna in the form of a meandered dipole sewn in with a single thread, and further, that can be connected to the RFID chip through the coupling system without galvanic junctions. The achieved parameters clearly indicate that the tag can correctly communicate with the read/write device as well as the coupling between its both parts works properly, and the impedance matching is possible in this case. The possibility of confectioning products with electronic identification tags at the textile factory site and improved resistance to the impact of environmental conditions are the main advantage of the proposed approach to the RFID devices designing. The RFIDtex transponder idea proposed by the authors was restricted in the patent no PL 231291 B1. Full article