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Maximization of the Operating Volume using HF RFID
Loop Antennas
Kevin D’hoe
1
, Nobby Stevens
1
, Jean-Pierre Goemaere
1
, Lieven De Strycker
1
and Bart Nauwelaers
2
1
DraMCo research group, Catholic University College Ghent, Association K. U. Leuven
Gebroeders Desmetstraat 1, 9000 Ghent, Belgium
2
Department of Electrical Engineering, ESAT, K. U. Leuven
Kasteelpark Arenberg 10, 3001 Leuven, Belgium
Abstract. This article describes how a passive radio frequency identification
(RFID) system is optimized. Our attention focuses on the operating volume of a
circular loop antenna. Hereby the design of loop antennas is given a new approach
to establish a maximum operating volume. Therefore, the off-axis magnetic field
is investigated. This is done for a circular loop in free space and in the vicinity
of a metal plane. A numerical approach is given towards the maximization of the
operating volume. The goal is to provide new insights into the design of a loop
antenna and enhance the reliability of the RFID system.
1 Introduction
Within the domain of industrial applications, Radio Frequency Identification (RFID)
has become a popular technology. Particularly when it comes to tracking and tracing
of objects, passive RFID technologies have been found to provide a suitable solution.
This technology is based on the principle of inductive coupling between two loop an-
tennas, namely a reader loop antenna and a transponder loop antenna. Although this
technology is well known, many problems occur when it is used in industrial environ-
ments. The presence of metals in the vicinity of the RFID loop antenna often causes
readout reliability issues. For this reason, the design of the reader loop antenna should
be optimal to achieve a maximum volume where a transponder is detected. This vol-
ume is called the operating volume. The research is based on previous work where the
optimal diameter [1] of a circular loop antenna was examined for ideal and non-ideal
conditions, e.g., the presence of a conducting plate in the vicinity of a loop antenna. In
that work [1], the magnetic field at the symmetry axis of a circular loop antenna is con-
sidered. Within this paper, we will focus on the investigation of the off-axis magnetic
field which will finally lead to new insights towards the design of a loop antenna. Two
specific cases were handled, namely a loop antenna in free space and a loop antenna
near a conducting plate. We will discuss how the operating volume is maximized and
which parameters should be taken into account. This approach will lead to the design
of reliable RFID systems.
D’hoe K., Stevens N., Goemaere J., De Strycker L. and Nauwelaers B.
Maximization of the Operating Volume using HF RFID Loop Antennas.
DOI: 10.5220/0003026000230029
In Proceedings of the 4th International Workshop on RFID Technology - Concepts, Applications, Challenges (ICEIS 2010), page
ISBN: 978-989-8425-11-9
Copyright
c
2010 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved