Abstract
Radio frequency identification (RFID) is an asymmetric
radio protocol, where uplink communication (from
transponder to reader) is implemented with backscattering
modulation. The idea was first demonstrated in the
1940's. One of the first consumer applications of RFID
was access control, and key cards based on an inductive
near field coupling are widely used even today. The
introduction of Schottky diodes to CMOS processes enabled
passive RFID, i.e. transponders without a battery, at
ultra high frequencies (UHF) with reasonable cost and
read range in the end of 1990's. This has opened up new
applications and inspired new research on RFID.
This thesis studies the radio frequency (RF) components
and general RF phenomena in RFID at UHF and millimetre
waves. The theoretical analysis of the radio path reveals
that the read range of a passive UHF system is ideally
limited by the downlink, i.e. the power transfer from
reader to the transponder. However, the architecture of
the reader RF front end is critical, because the
transmitted signal may couple a significant amount of
noise to the receiver, overpowering the faint reflection
from the transponder. In the thesis, two adaptive RF
front ends are introduced to eliminate the noise coupling
from the transmitter.
One of the most critical problems with UHF RFID has been
the detuning of transponder antennas on different
mounting platforms. The detuning may significantly
diminish the read range of the transponder, especially on
metal surfaces. In this thesis, two backscattering-based
measurement techniques for the transponder antennas are
presented. The detuning effect has been studied using
these measurement techniques, and a platform
tolerantantenna is introduced.
RFID at millimetre waves enables miniaturisation of the
reader antenna, and widening the data bandwidth over
short distances. This could be used to access wirelessly
mass memories with wide data bandwidth. A semipassive or
active transponder could communicate, e.g., with
automotive radars. The millimetre wave identification
(MMID) has been theoretically studied and experimentally
verified at 60 GHz.
Original language | English |
---|---|
Qualification | Doctor Degree |
Awarding Institution |
|
Supervisors/Advisors |
|
Award date | 30 Jan 2009 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 978-951-38-7133-8 |
Electronic ISBNs | 978-951-38-7134-5 |
Publication status | Published - 2008 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- radio frequency identification
- RFID
- ultra high frequency
- UHF
- millimetre
- waves
- millimetre wave identification
- MMID
- antenna
- scattering
- backscattering modulation
- scattering measurement
- reader device
- adaptive rf front end