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fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JRFID.2018.2845669, IEEE Journal
of Radio Frequency Identification
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Read Range/Rate Improvement of LF RFID-

Based Tracking Systems

Chokri Jebali, Member, IEEE, Ammar B. Kouki, Senior, IEEE


Abstract—The mechanical vibration of metal structures has a current to supply the tag-chip with the needed power to operate
great effect on Low Frequency (LF) Radio Frequency [10]. The required power is typically between 10 µW and 1 mW
Identification (RFID). The return signal link established from the depending on the tag type, and the response of the tag is an
tag to the reader is affected by induced current caused by magnetic
analog modulated signal [1]. Limited research efforts have
coupling. The interference affects the performance of the RFID
reader by distorting the binary information transmitted by the tag. assessed the acoustic and mechanical interference effect on
This paper presents a new practical technique that avoids the RFID reader performance [10]. Many in-lab tests prove that the
coupling interference, and improves the reading range. The RFID RFID system is liable to mechanical interference such as
system was analyzed at LF level to provide a new solution that random vibration with short duration and high intensity. Several
complies with ISO standards to satisfy the industrial application suggestions and studies tried to improve the RFID reader
requirements. Measurements and experimental results show the
performance for both near field and far field operations based
validity of the proposed solution and show a significant
enhancement in performance. on antenna size [11-17]. Others proposed new methods of
circuit design performance to extend the read range of the RFID
Index Terms—Tracking System, Electromagnetic coupling, reader [18-21].
induced current, RFID System, passive Tag. The paper is organized as follows: Section II introduces the
technical problem and focuses on the sensitivity of LF RFID
readers to mechanical vibration. In section III, a circuit design
I. INTRODUCTION architecture is analyzed and compared. Section III presents a

T he tracking of food products is an important factor in the

food industry to guarantee food safety. This is noticeable in
efforts to enhance the tracking code systems for beef cattle. The
detailed explanation of the solution to overcome the mechanical
vibration effect. Section IV includes measurement results to
validate the presented solution. Finally, the conclusion and
main role of the tracking system is to guarantee the quality and future work are introduced.
safety of the end product by using RFID systems [1]. The RFID
system tracks the animal through the different phases of the
supply chain. RFID applications using handheld technology are II. RESEARCH PROBLEM: ELECTROMAGNETIC INTERFERENCE
also involved in many industrial applications [2-6]. Over an CAUSED BY MECHANICAL VIBRATION
acceptable distance, RFID is used for identification purposes As a general rule, the communication model used by standard
without contact and without direct physical vision (e.g., animal LF RFID systems is based on the Reader Talk First (RTF)
identification, industrial monitoring, and inventory systems) [7, principle. The RTF communication starts from the reader to the
8]. A large set of unique identification can be supported by tag, by transmitting a signal that powers the tag remotely. The
RFID tags. Because the reading range of the RFID reader is an reader passes an AC current through the antenna (i.e., coil) to
important factor in providing forward power, several factors radiate an electromagnetic wave in free space. The radius of the
can act to reduce the distance at which the reader is able to coverage area depends on the coil size, and the excitation’s
power up the passive tag. This tag has a long operational life current. Thus, when a tag enters the covered area, it is
because it is battery-less, which makes it an appealing choice automatically illuminated by the incident electromagnetic
for different applications. The reader is a transceiver that wave; it absorbs the received power and re-radiates part of it.
generates power to communicate with the tag. Several The tag is made to absorb the maximum power in order to
approaches have been suggested in the literature to improve the provide a high remote power supply leading to the highest
reading range of RFID readers [9]. The power radiated from the possible operating distance. The RFID reader used for the
reader is captured by the tag coil and generates an induced traceability of animals and their identification follows the

This work was supported by the Natural Science and Engineering Council C. Jebali and A. B. Kouki are with the Department of Electrical Engineering,
of Canada (NSERC), Agri-Traçabilité Québec (ATQ) and Epsilia Inc. École de Technologie Supérieure, Montreal, QC H3C 1K3, Canada (e-mail:
Chokri.jebali@lacime.etsmtl.ca; ammar.kouki@etsmtl.ca ).

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occur. This mechanical vibration and the induced current inside

the trailer produce electromagnetic waves with random
frequencies. These waves cause interference to the signal sent
from the tag at 4 kHz to the reader, and the transmitted data are
distorted. This leads to degradation in reader performance, and
sometimes absence of detection.
The tag is able to communicate only in the period when the
Fig. 1. Block diagram of the entire LF RFID setup. The reader coil antenna reader is transmitting; the existence of the induced waves
transfers the electromagnetic wave to the tag and recovers the backscattered generated by the induced current in the metallic trailer causes
signal to the reader.
interference. This interference produced by the trailer which
standards given by ISO 11784/11785 to support the different behaves as a huge tag is superimposed on the backscattered
types of tags. The reader communicates with two types of tags signal of the tag. This phenomenon is the main source of poor
in two operating modes; Full-Duplex (FDX) mode, and Half- detection of the tag in reading range and rate. As shown in Fig.
Duplex (HDX) mode. The reader starts by communicating in 3(a), the main observation is that the LF RFID reader is very
FDX mode; if the tag supports FDX, it will be able to reply in sensitive to the mechanical vibration produced by the metallic
FDX mode; otherwise, if it supports HDX, it will wait until the trailer, especially, in the metallic area close to the reader
FDX signal ends, then it responds by HDX signal. antenna. Depending on the magnitude of the mechanical
This study focuses only on the FDX tag because it is the most vibration applied by the trailer, the generated interference
widely used in among all the ISO Conformant tags [25] and the waves can exceed the acceptable threshold causing deformation
one sensitive to the problem of in-band interference. In the of the received signal. To identify the source of the problem,
remainder of the paper, we will refer to FDX tags as simply simulation was performed using a 3D electromagnetic field
‘tag’. The tag intercepts the electromagnetic wave from the simulator provided by EMS software [22]. The simulator is
antenna and uses it to generate its own power. This power is based on the finite elements method. The simulation results
used to generate a sufficient current in the coil to transmit data provide remarkable insight to the induced current distribution
using analog modulation [1]. This mechanism is illustrated in in the conductor material of the trailer, which is very significant
Fig. 1. and can reach up to 1445 Amp/m2 [23].
Using ASK modulation depends on several factors such as: The vibration problem is related to the FDX tags. The LF
data transfer rate, number of ID bits, and additional redundancy reader continuously transmits a carrier at 134.2 kHz for 80 ms.
bits. The redundancy bits are placed in the code to help then the reader stops sending for 20 ms to listen to the HDX tag.
removing the bit errors introduced by communication channel The backscattered response from the FDX tag is demodulated
noise. These bits carry no information, but which are added to with a signal centered at 4 kHz. The most important finding was
observed when a set of random mechanical forces was applied
the information carrying bits of a tag identity to determine its
to the metallic structure.
accuracy. The tag’s device modulates the value of the load
The results are consistent with the electromagnetic
impedance of the tag coil at the rate of the amplitude shift simulation showing that an induced current density distribution
keying (ASK) corresponding to the transmitted logical data. is present around the reader antenna as given in Fig. 2. The re-
The impedance mismatch between the tag coil and the load radiated random signal covers the same frequency as the real
produces a standing wave. The amount of power re-radiated in tag (i.e., 4 kHz), but with a higher magnitude level because the
the space will be modified. This amount represents the trailer behaves like a huge coil when it receives power from the
significance of binary information, indicating the presence of a electromagnetic fields radiated from the reader antenna. The
tag. mechanical vibrations change the impedance of the coil. The
At the beginning, no cattle were used for tests since these total current passing through the reader antenna changes due to
were carried out in the research laboratory. We used tags that the superposition of the backscattered current of the virtual coil.
crossed the antenna in a metal structure that behaved practically These finding help to understand why the detection rate is low.
like the trailer. Then, we used cattle during the tests with our After several measurements, no significant differences were
RFID reader and our antenna fixed to the trailer’s frame in a found between the waveform of the FDX tag and the
cattle farm. The use of livestock adds more realism to the tests;
it also introduces other variable factors such as speed, the
orientation of the transponder (Tag) and difficulties in the
repetition of the same test.
The RFID reader antenna is installed in a transport trailer’s
door; each animal wearing a tag will be detected while entering
or exiting the trailer. In normal conditions, as the beef
approaches the antenna, its tag is detected and the
corresponding tag ID is stored in the reader’s memory. The
electromagnetic waves generated by the reader cut the metallic (a) (b)
structure of the trailer producing an induced current inside it. Fig. 2. Total magnetic field of the reader antenna (a) of the metallic structure,
As the beef moves inside the trailer, mechanical vibrations (b) the induced current density distribution in the cross-sectional view of the
metallic structure.

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(a) Without vibration

(a)

(b) With vibration

Fig. 4. Spectrum of a demodulated signal reflected from a tag after the

activation by the LF reader carrier, (a) backscattered signal without vibration,
(b) backscattered signal with vibration

phase noise and Allan variance analysis [24].

This study clarifies how the oscillator instability affects
(b) reader precision and how the frequency interval variation can
Fig. 3. Comparison between the vibration’s impact of the metal structure degrade the read rate of the RFID reader. The three oscillators
(trailer) on the response of the antenna and the impact of the vibration are; a CMOS MEMS programmable oscillator Si501 with a
measured by an accelerometer sensor
frequency range from 32 kHz to 100 MHz), a Crystal oscillator
Si510 with a frequency varying from 100 kHz to 250 MHz and
backscattered waveform issued from the trailer. Therefore, the
amount of backscattered current increased as high strength a port programmable oscillator LTC6903 starting from 1 kHz
vibration is applied to the trailer. We measured the vibration to 68 MHz. A programmable card with 16 bit microchip
effects with two tools; a 20 GS/s digital oscilloscope and an microcontroller is used to program the LTC6903 oscillator and
accelerometer, as shown in Fig. 3(b). The accelerometer generate an output signal with a predefined frequency. All the
provides clear harmony of the mechanical vibrations coming oscillators were set to generate a signal of 134.2 kHz for the LF
from the trailer compared to the signal provided from the reader as shown in Fig. 5. Each device’s output will be
oscilloscope. The signal shown in the scope is the envelope connected separately to the input of the amplification stage,
deformation of the received signal by the antenna reader. then to the antenna of the reader.
As mentioned, the current waveform behavior of the The output of an oscillator is expressed as
vibrating trailer matches the behavior of the FDX tag. Overall,
no significant differences were found between them, especially,
if their amplitudes are close to each other. The most surprising vt    A  A (t ) sin2f clk t   (t )  (1)
aspect of the measured results is the significant correlation
between the two waveforms, which gives rise to a similar tag’s Where  (t ) is a random process denoting the phase noise
response without ID information. This combination of findings and A (t ) is the amplitude noise.
provides some support for the conceptual premise that helps to The positive zero crossings occur at
develop a solution for this correlation. Fig. 4 gives an overview
of the spectrum reflected from an FDX Tag with no vibration
n  (t )
and with vibration. To resolve the problem, we suggest a t   n (2)
solution with two parts, one part improves the read range, and f clk 2f clk
the second part improves the read rate of the reader.
The second part of (2) is called the zero-crossing error,
III. CIRCUIT DESIGN ARCHITECTURE
which depends only on the phase error  (t ) . The intuitive
The proposed RFID system is designed to provide a
method to define jitter is to measure the RMS value of the
complete chip-level FDX and HDX, board-level authentication,
timing error. However, the phase noise is typically a non-
and traceability. In this section, we analyze the main sources of
stationary process, i.e., the variance of clock jitter approaches
signal instability, which affect RFID system efficiency. Three
infinity. Another metric tool for clock jitter is cycle-jitter. Cycle
commercial oscillators are implemented and tested for the jitter has the jitter of a single clock cycle, which is the difference
stability precision of the RFID reader. Most of the time, the of time error between two consecutive clock edges as expressed
instability characterization of an oscillator is given through by:

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 (t n )    (t n 1 )   IV. IMPROVING READ RATES FOR AN RFID SYSTEM WITH

    E  
2

 c2  E t   t n
2 
  (3) MECHANICAL VIBRATION
n 1
 2f clk  
This section describes a solution to overcome the vibration
causing an error in ID detection by altering the tag’s signal. Two
technical solutions are proposed after a characterization
To avoid any problem related to characterizing a Wiener procedure. To analyze the vibration effect, a set of random
process, it is recommended to use the technique of measuring forces is applied to the metallic structure, while the
the difference [24]. backscattered signals emanating from the tag are digitally
The three different jitter metrics of the commercial recorded during a period of time. As shown in Fig. 9, the
oscillators are illustrated in Fig. 6. The crystal oscillator in Fig. measurement of these signals showed that the vibration affects
6(a) has the least frequency instability compared to the MEMS the envelope of the received signal. The first solution reduces
and the programmable oscillators as shown in Fig. 6(b), (c). The the power level from the reader to the tag and ensures that the
impropriety period of the generated output signal of the tag’s load is perfectly matched to reduce the amplitude of the
oscillators gives an idea about the signal quality to be induced magnetic field in the metal structure which is
transmitted to the antenna after amplification. The instability proportional to the incident power. In addition, digital signal
criteria are expressed by the zero crossing error of each processing based on the average calculation of a set of frames
oscillator as: during the active period of the reader will be used.
Then, the signal envelope is re-calculated to ensure the
extraction of the tag ID. However, if the transmission power is
 12 t   22 t   32 t (4) decreased by changing the excitation current from 1100 mA to
600 mA the problem is not resolved. With low excitation
This frequency instability is one of the most significant current, the read range of the reader is shortened due to channel
factors limiting the read range of the RFID reader. Before conditions such as path-loss, wave absorption and reflection.
circuit design, the choice of the appropriate oscillator for the LF The required distance to detect a tag is significantly reduced.
RFID reader is based on zero crossing error level and the read The induced current of the metallic structure is still present. To
range of the tag. overcome this limit, a current detector is installed in the PCB
board of the reader to control the over limit of the desired
For each oscillator, the output power Vs frequency is
measured around the fundamental frequency 134.2 kHz as t(n-1) t(n) t(n+1) t(…) t(n+k)
shown in Fig. 7. The crystal oscillator has the highest power
around the fundamental frequency compared to the two other
oscillators. The programmed oscillator provides neither good 12t 12c
stability nor high output power. Depending on the performance
of each oscillator, a set of measurements was taken to assess the
efficiency of the reader read range as illustrated in Fig. 8. The
number of detected tags confirms the performance of each
(a)
oscillator rather than the frequency instability. The Crystal
oscillator has high read range detection Vs distance compared
to the MEMS and the programmable oscillators. t(n-1) t(n) t(n+1) t(…) t(n+k)

22t = E[t(n)2] 22c = E[(t(n+1) - t(n))2]

(b)

t(n-1) t(n) t(n+1) t(…) t(n+k)

32t 32c

(c)
Fig. 6. Clock jitter metrics of three oscillators, (a) Crystal, (b) MEMS, (c)
Fig. 5. PCB board of the oscillators and PCB board of the Programmable.
amplification stage with MOSFET devices.

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current, which is 750 mA in this case. This detector adjusts the

current in the hardware part of the reader to avoid exceeding the
desired current, especially when the metallic structure vibrates.
These applied vibrations change the impedance of the coil
(structure), and consequently, affect the current of the LF reader
coil to reach in some cases 1590 mA.
There is other evidence of the read range limit; this is seen
in the case of the coupling between the transmitter and receiver
hardware blocks, as they are in the same PCB board. The
impedance mismatch of the transmitter antenna, and the other
passive components of the receiver, result in leakage of some
transmitted power into the receiver. This reveals the significant
effect of leakage, which may critically degrade the performance
of tag detection; because it is much more intense than the
backscattered signal, when the tag used was further away from
Fig. 7. Output power comparison between the commercial oscillators tested in
the LF reader. To reduce current leakage, the PCB of the reader the RFID reader.
must be grounded to the metallic structure. This connection
creates an electrical separation of the receiver and the
transmitter blocks to neutralize the leakage current. Following
this treatment, an improved solution consists of keeping the
same power level and cancelling the vibration signal followed
by digital signal processing applied to the signal’s envelope. As
shown in Fig. 10, all samples with voltage level higher than a
given threshold, caused by the mechanical vibrations are
suppressed and replaced by a null signal. The average of the
resulting signal during the active period of the reader is
processed to decrease the probability of the reading error.

V. VALIDATION OF VIBRATION EFFECT REDUCING

TECHNIQUE
The solutions presented in the previous section were Fig. 8. Number of detections of the RFID reader based on each oscillator’s
device versus distance.
implemented and compared based on real measurements. Fig.
11, shows the experimental setup used for tag detection, and for shows the decreased performance of reader detection. This
the magnetic field measurements. The LF reader contains an processing increases the reader rate detection to 95% of the
embedded PCB board providing a carrier at 134.2 kHz, with an previous problem and helps to overcome the vibration problem.
envelope detector block, an LNA, a high amplification stage, The read range decrease described in the previous section is
and an analog-digital converter (ADC) as described in [23]. improved by an electronic solution since the effect of the
In this measurement, a commercial electromagnetic field leakage is much more intense than the backscatter signal of the
strength meter device (wave control SMP2) is equipped with a tag from such a distance. The transceiver block of the reader
field probe to sweep the frequency range from 1 Hz to 400 kHz. behaves as a second RFID tag, which conveys an intense signal
This device measures the magnetic field (Tesla: T) of the to the receiver part of the reader. This signal is added to the
antenna reader versus distance. This set up is used to assess the backscattered one of the RFID tag and affects the envelope to
tag identification rate before and after the tests of the proposed be identified. As the amplitude of the tag’s envelope decreases
solution, for improving the read range and the read rate of the compared to the amplitude of the leakage’s effect, the detection
LF reader. of the tag fails. This low detection is produced by the distance
After implementation of the first solution, the measured of the tag relative to the reader coil antenna.
envelope is still distorted, which gives an erroneous tag’s ID as To evaluate the reading range improvement of the LF RFID
shown with red color in fig. 11. Therefore, an improved signal reader, compared with the ordinary approach under the same
processing algorithm is applied to the affected envelope. The average power, the receiver block of the reader which generates
algorithm’s goal is to cancel the high noise levels in the the leakage effect is connected to the ground of the trailer to
envelope signal produced by vibrations as shown in Fig. 10. attenuate the undesirable intense signal. This connection
Then, the mean value of all recorded samples of the tag is transforms the impedance mismatch between the transmitter
applied. In Fig. 11, the average results of improved tag antenna, and the passive components of the receiver, which
detection are shown by the green curve, which corresponds to causes current leakage to the ground. Thus, this approach
the improved filtered measurements. The green tag reading reduces the intensity of the unwanted effect. The recovered
process is proven to fit well with the measured original signal from the tag becomes more intense compared to the
envelope without vibration, and becomes less sensitive to leakage’s effects for a range of distance. The results for the read
mechanical vibration effects, compared to the red one, which range improvement are summarized in Table 1, which gives the

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measured results obtained for both setups, groundless and Reader

Coil antenna
Structure

grounded reader PCB, versus distance. Instead of evaluating the

tag response for the detection using a GUI, and an oscilloscope, EM Probe

the magnetic field is also quantified for different tag positions.

A high rate of tag detection was reached with the new condition LF RFID Reader
(grounded) of the reader compared to the old condition (ground-
less). With different magnetic field intensities, and as the
distance between the tag and the reader antenna increases, the EM Reader

read rate varies, but the detection is improved with the proposed PC Scope

idea.

VI. CONCLUSION
This paper proposed a fortified traceability system based on
RFID technology. In the RFID system, the identification of
traceability units is based on reading the animal ear tag codes. Fig. 9. Electromagnetic field (EM) measurement using Wave control SMP2
However, at low frequency, the reader is more sensitive to system for the test detection of the RFID reader.
environmental conditions. The detection precision of an animal
4
ear tag is directly affected by the N-cycle jitter of the reference Signal envelope with vibration
oscillator, which reduces the long-term accuracy of the RFID 3 Signal envelope filtered
reader. To overcome this problem, three commercial oscillators 2

Voltage[Volt]
are tested. A signal processing algorithm is applied to increase
1
the read rate of the system; an experimental setup is used for tag
detection with different circuit designs to reach a high read -1
range level. -2

-3

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-5
0 5,000 10,000 15,000 20,000
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Distributed Diameter Reader Coil," IEEE Antennas and Wireless of Tunis, Tunisia, in 2004, and the M.Sc. and Ph.D.
Propagation Letters, vol. 15, pp. 1943-1946, 2016. degrees in electrical engineering from the University
[13] A. Farswan, A. K. Gautam, B. K. Kanaujia, and K. Rambabu, "Design of Tunis El-Manar, in 2006 and 2011, respectively. He
of Koch Fractal Circularly Polarized Antenna for Handheld UHF RFID served as a lecturer and as an assistant professor at
Reader Applications," IEEE Transactions on Antennas and Propagation, Tunis Carthage University from 2007 to 2013. After
vol. 64, pp. 771-775, 2016. his Ph.D. degree, he was a member of the High
[14] X. Liu, Y. Liu, and M. M. Tentzeris, "A Novel Circularly Polarized Frequency Electronics Circuits and Systems Laboratory, University of Tunis
Antenna With Coin-Shaped Patches and a Ring-Shaped Strip for El-Manar. He has been with the École de Technologie Superieure (ETS),
Worldwide UHF RFID Applications," IEEE Antennas and Wireless Montreal, QC, Canada, as a Post-Doctoral Fellow in the LACIME Laboratory
Propagation Letters, vol. 14, pp. 707-710, 2015. since 2013. He served as an expert-consultant in Focus Microwaves Inc., and
[15] A. Michel and P. Nepa, "UHF-RFID Desktop Reader Antennas: other Wireless industrial companies. He has authored and co-authored
Performance Analysis in the Near-Field Region," IEEE Antennas and numerous peer-reviewed journal and conference articles and one book. His
Wireless Propagation Letters, vol. 15, pp. 1430-1433, 2016. current research interests include RFID systems, the characterization,
[16] J. K. Pakkathillam, M. Kanagasabai, and M. G. N. Alsath, "Compact behavioral modeling, and linearization of radiofrequency power amplifiers and
Multiservice UHF RFID Reader Antenna for Near-Field and Far-Field transmitters and wireless power transfer system for healthcare.
Operations," IEEE Antennas and Wireless Propagation Letters, vol. 16,
pp. 149-152, 2017. Ammar B. Kouki (S’88, M’92, SM’01) received the
[17] H. Wegleiter, B. Schweighofer, C. Deinhammer, G. Holler, and P. B.S. (Hons) and M.S. degrees in engineering science
Fulmek, "Automatic Antenna Tuning Unit to Improve RFID System from Pennsylvania State University, University park,
Performance," IEEE Transactions on Instrumentation and in 1985 and 1987, respectively of Illinois at Urbana-
Measurement, vol. 60, pp. 2797-2803, 2011. Champaign, Urbana, in 1991, he was a consultant
[18] A. J. S. Boaventura and N. Carvalho, "Extending Reading Range of with the National Center for Supercomputing
Commercial RFID Readers," IEEE Transactions on Microwave Theory Applications. From 1991 to 1993, he was a Post-
and Techniques, vol. 61, pp. 633-640, 2013. doctoral fellow with the Microwave Research
[19] R. Chakraborty, S. Roy, and V. Jandhyala, "Revisiting RFID Link laboratory, École Polytechnique de Montréal, Montréal, QC, Canada. From
Budgets for Technology Scaling: Range Maximization of RFID Tags," 1994 to 1998, he was a senior Microwave Engineer with the Microwave
IEEE Transactions on Microwave Theory and Techniques, vol. 59, pp. Research Laboratory, where he was involved with power amplifier linearization
496-503, 2011. technique. In 1998, he cofounded AmpliX Inc., a company that specialized in
[20] B. J. Jang and H. Yoon, "Range Correlation Effect on the Phase Noise of RF linearizers for wireless and SatCom applications. In 1998, he joined the
an UHF RFID Reader," IEEE Microwave and Wireless Components faculty of the École de Technologie Supérieure (ETS), Montréal, QC, Canada,
Letters, vol. 18, pp. 827-829, 2008. where he is currently a full professor of Electrical Engineering, the Director of
[21] S. C. Jung, M. S. Kim, and Y. Yang, "Baseband Noise Reduction Method the LACIME Laboratory, the founding Director of the LTCC@ETS laboratory,
Using Captured TX Signal for UHF RFID Reader Applications," IEEE and one of the co-founders of ISR Technologies, a software-defined radio
Transactions on Industrial Electronics, vol. 59, pp. 592-598, 2012. company. He has authored or co-authored aver 190 peer-reviewed publications
[22] EMWorks. www.emworks.com. and hold six patents, with an additional three under review. He has diversified
[23] C. Jebali, R. Essaadali, K. Saidi, M. A. Séguin, and A. Kouki, research interests that cover the areas of radio communication and navigation
"Improving RFID tag detection in the presence of mechanical vibration," with focus on devices, intelligent, and efficient RF front-end/transceiver
in 2015 IEEE 16th Annual Wireless and Microwave Technology architectures, circuit and package integration in LTCC, and antenna and
Conference (WAMICON), 2015, pp. 1-3. propagation. He works on active device modeling and characterization, power-
[24] P. Keränen and J. Kostamovaara, "Oscillator Instability Effects in Time amplifier design, linearization, and efficient enhancement techniques. He is also
Interval Measurement," IEEE Transactions on Circuits and Systems I: involved in research on computational electromagnetic techniques for the
Regular Papers, vol. 60, pp. 1776-1786, 2013. modeling and design of passive-microwave structures.
[25] R. E. Floyd, "RFID in Animal-Tracking Applications", IEEE Potentials,
vol. 36, no. 5, pp.32-33, 2015.

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