A tuning transformer for the automatic adjustment of resonant loop antennas in RFID systems

Author

Steiner, Gerald ; Zangl, Hubert ; Fulmek, Paul ; Brasseur, Georg

Author_Institution

Inst. of Electr. Meas. & Meas. Signal Process., Graz Univ., Austria

Volume

2

fYear

2004

Firstpage

912

Abstract

Radio frequency identification (RFID) systems allow contactless communication between a small portable tag and a reader device. In this paper, we address the problem of performance degradations due to the detuning of resonant reader antennas in the widely used 13.56 MHz frequency band. A novel design of a tuning transformer for the adjustment of the center frequency of resonant loop antennas is proposed. The ferrite core of the transformer is premagnetized using an additional DC winding. The HF and DC windings are decoupled by an iron core. Besides the tuning, the transformer may also be used for impedance matching and for balancing an unbalanced signal. The function of the device was proven by network measurements. Key Words: Loop antenna, resonance tuning, RFID, tunable inductance.

Keywords

ferrites; impedance matching; inductance; loop antennas; radiofrequency identification; transformer cores; transformer windings; transformers; tuning; DC winding; RFID system; Radio frequency identification system; automatic adjustment; contactless communication; ferrite core; impedance matching; iron core; network measurement; portable tag; premagnetization; reader device; resonant loop antenna; tunable inductance; tuning transformer; Degradation; Ferrites; Frequency locked loops; Impedance matching; Iron; Radiofrequency identification; Resonance; Resonant frequency; Transformer cores; Tuning;

fLanguage

English

Publisher

ieee

Conference_Titel

Industrial Technology, 2004. IEEE ICIT '04. 2004 IEEE International Conference on

Print_ISBN

0-7803-8662-0

Type

conf

DOI

10.1109/ICIT.2004.1490196

Filename

1490196