Marjorie Grzeskowiak

Pebbles Tracking Thanks to RFID LF Multi-Loops Inductively Coupled Reader

The Radio Frequency IDentification (RFID) Low Frequency (LF) serial loops structure is proposed to improve TAGs detection when a TAG coil-antenna rotates by any angle, due to the tagged pebble moving. The detection zones of two types of TAGs (the token and glass TAG) and two types of reader coils, in function of the TAG size, TAG orientation and shape of the reader coils are tested. The effect of the proposed multi-coil inductively coupled is confirmed by measurement using a commercial LF RFID system.

A Multilayered Coil Antenna for Ingestible Capsule: Near-Field Magnetic Induction Link

A compact multilayered stacked ingestible coil antenna is investigated for medical systems. The inductive link, comprising a 5-layer transmitter coil antenna and a 3-turn receiver spiral coil, is modeled through a tissue-simulating liquid modeling the human body. The diameter and the thickness of the transmitter coil are respectively equal to 1 cm and 5 mm, while the dimensions of the receiver coil are equal to 7 × 8 cm2. The variations of the position and the orientation of the capsule antenna are taken into account to evaluate the coupling response between the two magnetically coupled coils. We found that the inductive link presents an attractive option for improving the lifetime of ingestible capsules.

Link Budget of Magnetic Antennas for Ingestible Capsule at 40 MHz

Magnetic antennas are suitable in short range medical in-body applications because they are less perturbed in the presence of the human tissues comparing to electrical antennas. After a preliminary study on magnetic antennas designed separately at 40 MHz with a matching system, a link budget between a spiral coil ingestible capsule transmitter antenna and a square coil onbody receiver antenna has been established in the presence of the human body. The efficiency (ratio of received power to transmitted power) of the magnetic induction link through a homogeneous human body (muscle) is equal to 0.6 % when the TX (transmitter) capsule is in front of the RX (receiver) antenna. If the transmission channel is a three-layered human body (muscle / fat / skin) the performances of the inductive link can be enhanced and the efficiency reaches 0.8 %. These performances can be improved (up to 1 %) when the dimensions of the receiver antenna increase. Consequently, the power consumption can be reduced and hence the battery life of the wireless capsule increases. Additionally, when the TX antenna is located randomly at an arbitrary orientation and position, the efficiency of the magnetic induction link can be improved by orienting the RX antenna parallel and perpendicularly to the human body surface.

Improvement of HF RFID Tag Detection With a Distributed Diameter Reader Coil

This letter focuses on 13.56 MHz high-frequency radio frequency identification (RFID) in the case of small tags detection, with an effective area below 1 cm2. In such an identification system, based on load modulation principle, the magnetic coupling coefficient k and quality factor of the RFID reader coil are the key parameters. The main goal of this letter is to improve the detection of small tags over a given surface of 10 × 10 cm2 by modifying the reader coil structure, and consequently the coupling coefficient k. Several coil designs are compared experimentally by distributing the diameters of their turns among three possible values. The design of the coils is based on empirical formulas that are in good agreement with experimental measurements. Electromagnetic simulations are performed to confirm the magnetic field distribution of the different designs. The results show that distributed diameter coil (DDC) as RFID reader coil is clearly efficient in this context of the RFID detection. The DDC structures determine the k factor, and, as k is low, the quality factor Q is a second parameter that can improve, in a second step, the RFID detection performances in function of the tag position and orientation.

Improving LF reader antenna volume of detection for RFID token tag thanks to Identical Coaxial Loops (ICLs) and in/out-of phase multiple-loops structures

This work concerns the prototyping of a low cost PCB based multiple loops antenna for LF 125 kHz RFID application. The multiple loops structure is considered for the context of small tags traceability, for example token tags such as circular HitagS (1-2 cm of diameter). The targeted volume is 20×20×10 cm3 for the moment. The position of the tag can be parallel or orthogonal to the reader antenna plane, with a variation of the angle position, and is moving inside the volume of detection (small objects in a storage basket in practice). The dedicated conception of a reader antenna is necessary because the application targets a volume of detection rather than maximum range detection. Additionally, the position of the tag is not known. The design considerations are based on a combination of Identical Coaxial Loops (ICL) and in/out-of phase loops structures whose advantages are discussed in terms of mutual inductance in the simulation part. An optimum diameter of 7,5 cm is noticed for square loops case. The realization of this structure shows qualitatively good results for our objectives and emphasizes a tradeoff between the two effects of coupling due to the two structures combined. As the tag is moving inside the volume, with an orientation (tag position test) unknown, our observations drive to the conclusion that the detection will be effective. Some perspectives are also clearly identified to improve the structure in the future.

Detecting range and coupling coefficient tradeoff with a multiple loops reader antenna for small size RFID LF tags

This paper summarizes some tests with Low Frequency (LF, 125 kHz) RFID tags of two types: Card and Token. These tests were done in order to evaluate the feasibility of an identification/traceability of tags which size is constrained and supposed to be detected inside a delimited volume of 40×40×10 cm3. As the size of the antenna tag is supposed to be very small, we improve the detection range and volume of definition by designing different reader antennas. Reader antennas presented are of two types whether they are based on single (SL) or multiple loops (ML). Detection range was evaluated for planar antennas (3 SL and one ML). Volume of definition for the detection was estimated by designing two-level prototypes of ML antennas. Results are discussed about the optimization possibility of detection range and volume thanks to ML.

Magnetic loop antenna for wireless capsule endoscopy inside the human body operating at 315 MHz: Near field behavior

In ingestible systems, the antenna suffers from deterioration of performances due to surrounding dissipative tissues. A small circular magnetic loop antenna, whose diameter is equal to 1 cm and thickness is equal to 0.5 mm operating at the frequency of 315 MHz in the ISM band, is proposed to limit this degradation. The electric properties of the human body, having a high dielectric constant and low impedance, are considered to design and simulate the loop antenna. We found that the magnetic field is less attenuated than the electric field in the human body that improves the signal level received by near field magnetic coupling.

3D HF RFID reader antenna for tag detection in different angular orientations

Herein, a 3D 13, 56 MHz (HF) RFID reader antenna is proposed in order to optimize detection performance whatever the tag angular positioning. The design is made of a multi-loop structure, based on serial complementary antennas, as said “twisted” antennas. The RFID tag detection is optimized by two factors which rely on the modifications of the magnetic field (i) vectorial distribution and (ii) magnitude density. The reader antenna design is analyzed with electromagnetic simulation under HFSS (High Frequency Electromagnetic Field Simulation), and validated by detection measurements, in coplanar mode. A multi-loop structure, composed by 4 sub-loops, is then conformed onto a tube surface to provide the 3D structure. The goal of this improvement is to provide tag detection for any angular positions. At the center of the tube (3D reader structure), the detection of the tag is performed whatever its angular orientation, that is to say for any radial orientation.

Study of Lateral Scaling Impact on the Frequency Performance of SiGe Heterojunction Bipolar Phototransistor

The influence of the lateral scaling such as emitter width and length on the frequency behavior of SiGe bipolar transistor is experimentally studied. Electrical transistors of different emitter sizes are designed and fabricated by using a commercial bipolar transistor technology. The effect of peripheral current and collector current spreading on electrical bipolar transistor performances are analyzed in regards to the state of the art. Furthermore, the lateral scaling effect on SiGe phototransistor electrical and opto-microwave frequency behavior is studied. The impact of the lateral flow of photo-generated carriers toward the optical opening in phototransistor structure is investigated. Moreover, the 2-D carrier flow effect on the opto-microwave frequency behavior of the phototransistor is characterized through opto-microwave scanning near-field optical microscopy measurements, in the course of which the intrinsic parameters, such as transit time and junction capacitances are extracted over the surface of the phototransistor. An intrinsic optical transition frequency of 6.5 GHz is measured for

Sub-coil in reader antenna for HF RFID volume detection improvment

10\times 10\,\,\mu \text {m}^{2}