Open AccessNumerical analysis of wireless power transfer in near-field UHF-RFID systems
Author(s) -
Alice Buffi,
A. Michel,
Paolo Nepa,
Giuliano Manara
Publication year - 2017
Publication title -
wireless power transfer
Language(s) - English
Resource type - Journals
ISSN - 2052-8418
DOI - 10.1017/wpt.2017.16
Subject(s) - antenna (radio) , ultra high frequency , radio frequency identification , maximum power transfer theorem , input impedance , computer science , acoustics , electrical impedance , electronic engineering , electrical engineering , power (physics) , engineering , telecommunications , physics , computer security , quantum mechanics
A preliminary numerical analysis of the power transfer efficiency (PTE) for the forward link of near-field (NF) ultra high frequency (UHF)-radio frequency identification (RFID) systems is addressed in this paper, by resorting to an impedance matrix approach where the matrix entries are determined through full-wave simulations. The paper is aimed to quantify the NF-coupling effects on the PTE, as a function of the distance between the reader and tag antennas. To allow for a PTE comparison between different reader and tag antenna pairs, a benchmarking tag-loading condition has been assumed, where the tag antenna is loaded with the impedance that maximizes the PTE. In a more realistic loading condition, the load impedance is assumed as equal to the conjugate of the tag antenna input impedance. Full-wave simulations use accurate antenna models of commercial UHF-RFID passive tags and reader antennas. Finally, a “shape-matched antenna” configuration has been selected, where the reader antenna is assumed as identical to the tag antenna. It is shown that the above configuration could be a valuable compact solution, at least for those systems where the relative orientation/position between the tag and reader antennas can be controlled, and their separation is of the order of a few centimeters or less