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Applications involving superconductors generate an increasing interest nowadays in various fields (medical imaging, motors/generators, particle accelerators, shielding, etc.). Measuring the local magnetic flux density around the whole superconducting structure is a key element towards the improvement of these applications. The context of this master’s thesis is the need to measure and understand the details of the 3D spatial distribution of the flux density at cryogenic temperature (77 K). However, 3-axis Hall probes operating at cryogenic temperature for a flux density above the mT range are not commercialized anymore. The goal of this master’s thesis is to design, build and characterize experimentally a 3-axis cryogenic magnetic field sensor operating at several tens of mT. 

In the first part of this work, guidelines are established in order to build an experimental chamber able to keep a region of space at room temperature while it is immersed into liquid nitrogen. This way, a commercial Hall probe suited for room temperature measurements can artificially be used in a cryogenic environment. The resulting device (experimental chamber with the probe) should be usable to measure the magnetic flux density over superconducting structures. As a result, the experimental chamber should be of minimal size and the Hall probe should be placed as close as possible to these structures. A first analytical model is developed, before validating the results experimentally.

In the second part, printed circuit boards are developed to interface and calibrate the 3-axis Hall probe to be placed in the experimental chamber. The probe shows a linear range of more than ~155 mT in each direction and a typical noise level of a few hundreds of µT. Additionally, the sensitivity and the offset are shown to be almost temperature independent between 5°C and 65°C.

In the last part, the final experimental chamber is assembled. The chamber outer diameter is 20 mm and the active region of the Hall probe is determined to be located at 2.2 ± 0.25 mm from the bottom end. A proportional integral (PI) temperature controller is implemented to ensure that the Hall probe stays around 25°C with few variations, irrespective of the possibly cryogenic environment. The resulting device is used to perform two experiments on superconducting structures; the measurement data are compared to both analytical and finite element models. As a result, the device can perform reliable and accurate measurements in cryogenic conditions (77 K) as soon as the flux density exceeds ~0.5 mT.

3-axis Hall probe --- magnetic measurements --- cryogenic --- superconductors --- experimental realization --- magnetic sensor --- Ingénierie, informatique & technologie > Ingénierie électrique & électronique

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This Special Issue focuses on the state-of-the-art results from the definition and design of filters for low- and high-frequency applications and systems. Different technologies and solutions are commonly adopted for filter definition, from electrical to electromechanical and mechanical solutions, from passive to active devices, and from hybrid to integrated designs. Aspects related to both theoretical and experimental research in filter design, CAD modeling and novel technologies and applications, as well as filter fabrication, characterization and testing, are covered. The proposed research articles deal with different topics as follows: Modeling, design and simulation of filters; Processes and fabrication technologies for filters; Automated characterization and test of filters; Voltage and current mode filters; Integrated and discrete filters; Passive and active filters; Variable filters, characterization and tunability.

History of engineering & technology --- analogue-to-digital conversion --- ATHOS soft X-ray beamline --- broadband noise --- Hall probe --- offset fluctuation and drift --- three-axis teslameter --- undulator --- power line communication (PLC) --- conducted disturbances --- anti-interference filter --- smart home --- low-pass filter (LPF) --- stepped impedance resonator (SIR) --- hairpin resonator --- internal coupling --- defected ground structure (DGS) --- current mode --- universal filter --- VCII --- voltage conveyor --- SIMO filter --- microwave dielectric ceramics --- filter --- additive manufacturing --- digital light processing --- post annealing --- dielectric properties --- wideband --- bandpass filter --- quarter wavelength --- stepped-impedance resonator (SIR) --- ultra-wideband --- stub-loaded --- stepped impedance resonator --- active filters --- anti-aliasing filters --- HBT --- inductorless --- low-pass filters --- SiGe --- switched-capacitor filters --- low-voltage --- finFET --- operational amplifier --- voltage-controlled oscillator --- unity-gain bandwidth --- varactor --- total harmonic distortion --- phase noise --- active inductor --- MMIC --- tunable filters

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Electromagnetic (EM) waves carry energy through propagation in space. This radiation associates with entangled electric and magnetic fields which must exist simultaneously. Although all EM waves travel at the speed of light in vacuum, they cover a wide range of frequencies called the EM spectrum. The various portions of the EM spectrum are referred to by various names based on their different attributes in the emission, transmission, and absorption of the corresponding waves and also based on their different practical applications. There are no certain boundaries separating these various portions, and the ranges tend to overlap. Overall, the EM spectrum, from the lowest to the highest frequency (longest to shortest wavelength) contains the following waves: radio frequency (RF), microwaves, millimeter waves, terahertz, infrared, visible light, ultraviolet, X-rays, and gamma rays. This Special Issue consists of sixteen papers covering a broad range of topics related to the applications of EM waves, from the design of filters and antennas for wireless communications to biomedical imaging and sensing and beyond.

History of engineering & technology --- bonding wire --- S parameters --- electromagnetic simulation --- port embedding --- balanced bandpass filter --- common mode suppression --- spurline --- source-load coupling --- stepped impedance resonator (SIR) --- open-ended waveguide --- slow-wave --- endfire --- radiation --- dispersion --- gain --- energy verification --- Hall probe --- dipole --- movable slit --- Goubau line --- non-invasive blood glucose measurement --- Acu-check --- lancet --- leaky waves --- surface waves --- ultra-wideband --- THz absorber --- high absorption --- polarization independent --- holography --- microwave imaging --- microwave measurement system --- nondestructive testing --- electromagnetic compatibility --- protection of information --- electromagnetic emissions --- computers and information processing --- data acquisition --- image recognition --- pattern recognition --- image processing --- graphic information --- LED array --- laser printer --- compromising emanations --- electromagnetic infiltration --- reconstruction --- non-invasive data acquisition --- Fourier series expansion --- nanorod --- multimode --- propagation characteristics --- guided wave --- bandpass filter --- half-wavelength resonator --- insertion loss --- phantom measurement system --- bone lesion detection --- ground penetrating radar --- reverse time migration --- Tibetan Plateau --- permafrost active layer --- internal structure --- Chebyshev filter --- cavity --- metamaterial --- waveguide --- X-band --- meta-resonator --- machine learning --- material identification --- microwave sensor array --- microwave waveguide --- dipole and horn antennas --- carbon-composite material --- graphene --- antenna measurements --- electromagnetic waves --- bonding wire --- S parameters --- electromagnetic simulation --- port embedding --- balanced bandpass filter --- common mode suppression --- spurline --- source-load coupling --- stepped impedance resonator (SIR) --- open-ended waveguide --- slow-wave --- endfire --- radiation --- dispersion --- gain --- energy verification --- Hall probe --- dipole --- movable slit --- Goubau line --- non-invasive blood glucose measurement --- Acu-check --- lancet --- leaky waves --- surface waves --- ultra-wideband --- THz absorber --- high absorption --- polarization independent --- holography --- microwave imaging --- microwave measurement system --- nondestructive testing --- electromagnetic compatibility --- protection of information --- electromagnetic emissions --- computers and information processing --- data acquisition --- image recognition --- pattern recognition --- image processing --- graphic information --- LED array --- laser printer --- compromising emanations --- electromagnetic infiltration --- reconstruction --- non-invasive data acquisition --- Fourier series expansion --- nanorod --- multimode --- propagation characteristics --- guided wave --- bandpass filter --- half-wavelength resonator --- insertion loss --- phantom measurement system --- bone lesion detection --- ground penetrating radar --- reverse time migration --- Tibetan Plateau --- permafrost active layer --- internal structure --- Chebyshev filter --- cavity --- metamaterial --- waveguide --- X-band --- meta-resonator --- machine learning --- material identification --- microwave sensor array --- microwave waveguide --- dipole and horn antennas --- carbon-composite material --- graphene --- antenna measurements --- electromagnetic waves

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Electromagnetic (EM) waves carry energy through propagation in space. This radiation associates with entangled electric and magnetic fields which must exist simultaneously. Although all EM waves travel at the speed of light in vacuum, they cover a wide range of frequencies called the EM spectrum. The various portions of the EM spectrum are referred to by various names based on their different attributes in the emission, transmission, and absorption of the corresponding waves and also based on their different practical applications. There are no certain boundaries separating these various portions, and the ranges tend to overlap. Overall, the EM spectrum, from the lowest to the highest frequency (longest to shortest wavelength) contains the following waves: radio frequency (RF), microwaves, millimeter waves, terahertz, infrared, visible light, ultraviolet, X-rays, and gamma rays. This Special Issue consists of sixteen papers covering a broad range of topics related to the applications of EM waves, from the design of filters and antennas for wireless communications to biomedical imaging and sensing and beyond.

bonding wire --- S parameters --- electromagnetic simulation --- port embedding --- balanced bandpass filter --- common mode suppression --- spurline --- source–load coupling --- stepped impedance resonator (SIR) --- open-ended waveguide --- slow-wave --- endfire --- radiation --- dispersion --- gain --- energy verification --- Hall probe --- dipole --- movable slit --- Goubau line --- non-invasive blood glucose measurement --- Acu-check --- lancet --- leaky waves --- surface waves --- ultra-wideband --- THz absorber --- high absorption --- polarization independent --- holography --- microwave imaging --- microwave measurement system --- nondestructive testing --- electromagnetic compatibility --- protection of information --- electromagnetic emissions --- computers and information processing --- data acquisition --- image recognition --- pattern recognition --- image processing --- graphic information --- LED array --- laser printer --- compromising emanations --- electromagnetic infiltration --- reconstruction --- non-invasive data acquisition --- Fourier series expansion --- nanorod --- multimode --- propagation characteristics --- guided wave --- bandpass filter --- half-wavelength resonator --- insertion loss --- phantom measurement system --- bone lesion detection --- ground penetrating radar --- reverse time migration --- Tibetan Plateau --- permafrost active layer --- internal structure --- Chebyshev filter --- cavity --- metamaterial --- waveguide --- X-band --- meta-resonator --- machine learning --- material identification --- microwave sensor array --- microwave waveguide --- dipole and horn antennas --- carbon-composite material --- graphene --- antenna measurements --- electromagnetic waves --- n/a --- source-load coupling