Differential Transmission Line Loop for RFID Reactive Near-Field Coupling
Artikel i vetenskaplig tidskrift, 2018

The differential transmission line loop (DTLL) as an efficient reactive near-field coupling element for programming of radio frequency identification (RFID) inlays is proposed. It is validated, with simulations and measurements, that the differential excitation and the presence of a ground plane are fundamental properties for high performance in coupling while providing high electromagnetic isolation. As a proof of concept, super elliptical loop geometries as coupling elements are investigated for a number of commercially available inlay geometries. From simulations of the DTLL and inlay antenna, coupling efficiencies higher than 80% are predicted. Measurements of the \Delta \Gamma -value indicate a nonlinear input impedance with power, and verify the high values of simulated coupling efficiency. The threshold power levels read from interrogator are below 5 dBm, which are considered as very low in inlay encoding, and hence show that the DTLL is a promising candidate for efficient RFID programming in the reactive near field.

power gain

reactive near field (RNF)

ultrahigh frequency (UHF)

radio frequency identification (RFID)

differential transmission line loop (DTLL)


RFID inlay


Markus Frank

SATO Techno Lab Europe

Mattias Thorsell


Peter Enoksson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Elektronikmaterial och system

IEEE Transactions on Microwave Theory and Techniques

0018-9480 (ISSN)

Vol. 66 2141-2153


Teknisk mekanik

Strömningsmekanik och akustik

Annan elektroteknik och elektronik