A printed array composed of 4 bow-tie slot antennas is designed on Alumina substrate to operate i... more A printed array composed of 4 bow-tie slot antennas is designed on Alumina substrate to operate in the Ka-band. The reported design is suitable for the integration in microwave systems used in radar or radio astronomy detection. The array uses aperture coupling between the CPW feed lines and a parasitic patch, made on Arlon 25N, with the substrates layers in a hi-lo configuration. In order to feed the array, a combination of Wilkinson power dividers with microstrip to CPW transitions is designed to complete the feeding network. Two hemispherical lenses made of low-permittivity materials, Plexiglas and Teflon, joined to the array, enhance its performance. Simulation results exhibit a frequency range of operation from 24 to 40 GHz with a maximum impedance bandwidth of 25% achieved for-10 dB return loss. The radiation patterns show a maximum gain of around 15 dB with HPBW (half power bandwidth) of ± 8º in both E and H planes, and whose first side lobes are more than 15 dB below the main lobe. The presented results of this array will be considered as a feasibility study to the phase II of the experiment called QUIJOTE, which is designed to study the polarization of the Cosmic Microwave Background (CMB).
Observations that require large physical instrument dimensions and/or a considerable amount of cr... more Observations that require large physical instrument dimensions and/or a considerable amount of cryogens, as it is for example the case for high spatial resolution far infrared astronomy, currently still face technological limits for their execution from space. The high cost and finality of space missions furthermore call for a very low risk approach and entail long development times. For certain spectral regions, prominently including the mid- to far-infrared as well as parts of the ultraviolet, stratospheric balloons offer a flexible and affordable complement to space telescopes, with short development times and comparatively good observing conditions. Yet, the entry burden to use balloon-borne telescopes is high, with research groups typically having to shoulder part of the infrastructure development as well. Aiming to ease access to balloon-based observations, we present the efforts towards a community-accessible balloon-based observatory, the European Stratospheric Balloon Obser...
In this paper, we propose the implementation of a small refractor telescope inside a 2U-cubesat. ... more In this paper, we propose the implementation of a small refractor telescope inside a 2U-cubesat. The satellite will carry out photometric studies of nearby bright stars aiming the monitoring of exoplanet transits. The telescope consists of an achromatic 80mm-diameter lens working at f/5 coupled to a 1600 × 1220 CCD camera. Resulting images will be sent to the ground using an FM transmitter, operating at a frequency of 437.465MHz and at a rate of 9600 bps. The 2U-cubesat includes an attitude control system which consists of a 3-axis mechanical gyroscope in turn composed of 6 engines acting as reaction wheels. The maximum power consumption of the full system is around 15 Watts. A GPS installed in the communication system will provide the satellite location coordinates. In addition, an optical 8-inch telescope, with f/10 focal ratio, will be used for tracking the satellite from ground.
4 paginas, 7 figuras.-- Trabajo presentado al 25 Simposium Nacional de la Union Cientifica Intern... more 4 paginas, 7 figuras.-- Trabajo presentado al 25 Simposium Nacional de la Union Cientifica Internacional de Radio (URSI) en la sesion III: Antenas III, celebrado en Bilbao (Espana) del 15 al 17 de septiembre de 2010.
Los cansat son conocidos en casi todo el mundo. Su principal objetivo es transmitir a los estudia... more Los cansat son conocidos en casi todo el mundo. Su principal objetivo es transmitir a los estudiantes universitarios los conceptos basicos de diseno y construccion de satelites artificiales. La mayoria de las universidades mas importantes de diversos paises que cuentan con una facultad de ingenieria y ciencias exactas han construido al menos uno de estos dispositivos como actividad extraescolar para sus alumnos, mediante cursos, talleres o a traves de los programas de capacitacion que las agencias espaciales ofrecen para captar las futuras generaciones de ingenieros y cientificos en el area espacial (Walker et al., 2010).
Stratospheric balloons offer accessible and affordable platforms for observations in atmosphere-c... more Stratospheric balloons offer accessible and affordable platforms for observations in atmosphere-constrained wavelength ranges. At the same time, they can serve as an effective step for technology demonstration towards future space applications of instruments and other hardware. The Stratospheric UV Demonstrator of an Imaging Observatory (STUDIO) is a balloon-borne platform and mission carrying an imaging micro-channel plate (MCP) detector on a 0.5 m aperture telescope. STUDIO is currently planned to fly during the summer turnaround conditions over Esrange, Sweden, in the 2022 season. For details on the ultraviolet (UV) detector, see the contribution of Conti et al. to this symposium. 1 The scientific goal of the mission is to survey for variable hot compact stars and flaring M-dwarf stars within the galactic plane. At the same time, the mission acts as a demonstrator for a versatile and scalable astronomical balloon platform as well as for the aforementioned MCP instrument. The gondola is designed to allow the use of different instruments or telescopes. Furthermore, it is designed to serve for several, also longer, flights, which are envisioned under the European Stratospheric Balloon Observatory (ESBO) initiative. In this paper, we present the design and current status of manufacturing and testing of the STUDIO platform. We furthermore present the current plans for the flight and observations from Esrange. 1. STATE OF THE ART IN BALLOON-BORNE ASTRONOMY The idea of using stratospheric balloons to overcome the opacity of Earth's atmosphere for astronomical observations is not new. Historically, the advantages were obvious: spacecraft did not exist or were hardly available and capabilities of airplanes were limited, leaving balloons as the only option to move instruments above most of the atmosphere. Nowadays, the benefits do not seem as clear: both spacecraft and airplanes provide powerful observation platforms and ground-based telescopes invest large efforts into compensating atmospheric influences. However, even in the era of nano-and microsatellites, space observatories are intrinsically expensive and bear operational limitations: development times are long, updates or corrections of the instrumentation are usually not possible after launch, and consumables, such as cryogenic coolant fluids, cannot be refilled or replaced, as seen with the Herschel Space Observatory. Furthermore, rather conservative approaches towards new technologies are used to minimize risks of expensive failure. Ground-based and airborne telescopes, on the other hand, still suffer from fundamental limitations imposed by the atmosphere at certain wavelengths. On the other hand, technological advances have made balloon-borne telescopes more attractive over the last couple of years. These particularly include more reliable balloons and the opening of long-duration flight routes, allowing flight durations of 30 to 40 days on "conventional" long duration routes and promising 50 to 100 days on ultra long duration routes. Consequently, the last couple of years saw an increase of balloon-astronomy initiatives aiming at more regularly
International Journal of Antennas and Propagation, 2017
We propose a model of antenna-coupled microbolometer to be included in an array for receiving and... more We propose a model of antenna-coupled microbolometer to be included in an array for receiving and detecting long wave infrared (LWIR) electromagnetic radiation. The antenna is joined to microstrip bandpass filters thus forming a single metal structure to define the operation frequency band. The antenna and microstrip filters are modeled in aluminum thin film. The microbolometer is modeled with superconducting niobium, all together on a silicon nitride membrane. The squared pixel structure is designed on a support frame of 20 μm in size. Simulation results for this antenna exhibit a frequency range of operation from 27 to 35 THz and is configured for two arrays, one of 10×10 and the other one of 50×50 elements. The device has been simulated by means of the commercial electromagnetic software (HFSS), which is based on the finite elements method. The predicted values for the figures of merit of this microbolometer are as follows: τ=5.8 ns, Rv=5.3×103 V/W, and D⁎ = 2.07×1010 cmHz/W, res...
In this paper, we describe the process to construct a pico-satellite mounted in a bottle of polye... more In this paper, we describe the process to construct a pico-satellite mounted in a bottle of polyethylene terephthalate (PET) of 345 ml. The assembly and tests were made during the 6th CanSat Leader Training Program (CLTP-6) at University Hokkaido-Japan in the summer 2015. The pico-satellite was launched in the facilities of Uematsu Electric Co. Ltd. in Akabira-Japan by a paper model rocket, which achieved a height of approximately 100 m. The mission was designed to measure physical variables, such as temperature and humidity using electronic sensors. During the flight, we observed that the temperature inside the rocket was ∼0.5 • C higher than the temperature of the environment. We registered a humidity difference of ∼5%, measured between the maximum height and the landing point. The flight pattern was projected to a plane that covers an area of 50 m × 50 m by means the coordinates of a GPS.
This report presents two proposals of antenna designs suitable to be included in arrays for multi... more This report presents two proposals of antenna designs suitable to be included in arrays for multi-frequency operation in the ranges from ∼10 to ∼60 GHz and from ∼130 to 300 GHz, both aimed to be applied in Cosmic Microwave Background (CMB) experiments. The antennas exhibit small sizes and wide bandwidth approaching 131% and 79% respectively. The radiation characteristics for a single element and the total directivity for configurations of 5x5 and 15x15 elements array were simulated by means of HFSS (Ansoft) software.
We propose a pixel design, aimed to be included in an array, receiving and detecting simultaneous... more We propose a pixel design, aimed to be included in an array, receiving and detecting simultaneously two bands of the Cosmic Microwave Background (CMB). It is composed of a bowtie antenna, feeding a diplexer structure to separate the signal towards two bolometric detectors at 150 and 220 GHz. The diplexer makes use of differential transmission lines of Coplanar Striplines (CPS) and Broadside Coupled Lines (BCL) types, for filtering and separation purposes. The antenna and diplexer are planned to be fabricated in a superconductive niobium thin film deposited on a Silicon substrate, while NbSi bolometers will lie on a SiN membrane. The device has been simulated by means of ADS (Agilent), CST Microwave Studio and HFSS (Ansoft) softwares. Final dimensions that take into account the kinetic inductance of the superconducting lines are proposed. Promising computation results are found, with signal separation up to 20 dB.
We propose a bow-tie slot antenna fed by a microstrip to CPW transition to operate in the mm wave... more We propose a bow-tie slot antenna fed by a microstrip to CPW transition to operate in the mm wave-band from 29 to 45 GHz. The measured results exhibit a maximum impedance bandwidth of 43% for VSWR<2, and an average gain of 10 dB. The antenna is suitable for the integration with microstrip circuits and mm-wave MMIC. The antenna is mounted on a mechanical structure with a movable reflector plane which provides the adjustment for the return losses. The whole design facilitates the cooling process when this antenna is used in low temperature experiments.
This paper describes the impact of the Planck Low Frequency Instrument front end physical tempera... more This paper describes the impact of the Planck Low Frequency Instrument front end physical temperature fluctuations on the output signal. The origin of thermal instabilities in the instrument are discussed, and an analytical model of their propagation and impact on the receivers signal is described. The experimental test setup dedicated to evaluate these effects during the instrument ground calibration is reported together with data analysis methods. Finally, main results obtained are discussed and compared to the requirements.
Progress In Electromagnetics Research Letters, 2011
Measurements of the radiation patterns from a planar array of bow-tie slot antennas coupled throu... more Measurements of the radiation patterns from a planar array of bow-tie slot antennas coupled through an extended hemispherical lens are reported. The design operates over 10% bandwidth centred at 30 GHz with a return loss of 10 dB. A moderate directivity from the integrated lenses of 13 dB with half-power beamwidth (HPBW) of 10 • is achieved. The reduced size of this design is suitable for the integration with millimetre wave circuits.
This paper describes an experimental setup for the spectral calibration of bolometric detectors u... more This paper describes an experimental setup for the spectral calibration of bolometric detectors used in radioastronomy. The system is composed of a Martin-Puplett interferometer with two identical artificial blackbody sources operating in the vacuum mode at 77 K and 300 K simultaneously. One source is integrated into a liquid nitrogen cryostat, and the other one into a vacuum chamber at room temperature. The sources were designed with a combination of conical with cylindrical geometries thus forming an orthogonal configuration to match the internal optics of the interfermometer. With a simple mathematical model we estimated emissivities of ε $ 0:995 for each source.
ABSTRACT We carried out measurements of thermal conductance and thermal contact resistance of two... more ABSTRACT We carried out measurements of thermal conductance and thermal contact resistance of two materials commonly used in low temperature laboratories such as an Electro-Magnetic Interference (EMI) Filter and Stycast 2850 FT epoxy. Both samples were attached on a heat sink made of oxygen-free high thermal conductivity (OFHC) copper and characterized at temperatures between 0.3 K and 4.5 K, using a 3He refrigerator mounted on a pumped 4He cryostat. For the EMI filter we applied a varied input power from 0.25 up to 50 μW to the heater which is soldered to its central pin, whereas for a thin layer of Stycast sandwiched between a copper strap and the heat sink we applied an input power from 10 up to 810 μW. The temperature dependences obtained in each case were $K=3\,{\cdot}\,10^{-5}T^{2.3}~[\frac{\mathrm{W}}{\mathrm{K}}]$ , and $R_{K}=8.4\,{\cdot}\,10^{-3}T^{1.7}\ [\frac{\mathrm{W}}{\mathrm{cm}^{2}\,\mathrm{K}}]$ respectively.
We describe a simple and efficient improvement to the Martin-Puplett interferometer, built at the... more We describe a simple and efficient improvement to the Martin-Puplett interferometer, built at the Max-Planck Institute for Radioastronomy in Bonn. Interferograms with its corresponding spectra taken with the interferometer operating in the vacuum mode, have confirmed that the detector's signal increases up to $10% when the microwave foam absorbers used as radiation sources are replaced by blackbody cavities.
A printed array composed of 4 bow-tie slot antennas is designed on Alumina substrate to operate i... more A printed array composed of 4 bow-tie slot antennas is designed on Alumina substrate to operate in the Ka-band. The reported design is suitable for the integration in microwave systems used in radar or radio astronomy detection. The array uses aperture coupling between the CPW feed lines and a parasitic patch, made on Arlon 25N, with the substrates layers in a hi-lo configuration. In order to feed the array, a combination of Wilkinson power dividers with microstrip to CPW transitions is designed to complete the feeding network. Two hemispherical lenses made of low-permittivity materials, Plexiglas and Teflon, joined to the array, enhance its performance. Simulation results exhibit a frequency range of operation from 24 to 40 GHz with a maximum impedance bandwidth of 25% achieved for-10 dB return loss. The radiation patterns show a maximum gain of around 15 dB with HPBW (half power bandwidth) of ± 8º in both E and H planes, and whose first side lobes are more than 15 dB below the main lobe. The presented results of this array will be considered as a feasibility study to the phase II of the experiment called QUIJOTE, which is designed to study the polarization of the Cosmic Microwave Background (CMB).
Observations that require large physical instrument dimensions and/or a considerable amount of cr... more Observations that require large physical instrument dimensions and/or a considerable amount of cryogens, as it is for example the case for high spatial resolution far infrared astronomy, currently still face technological limits for their execution from space. The high cost and finality of space missions furthermore call for a very low risk approach and entail long development times. For certain spectral regions, prominently including the mid- to far-infrared as well as parts of the ultraviolet, stratospheric balloons offer a flexible and affordable complement to space telescopes, with short development times and comparatively good observing conditions. Yet, the entry burden to use balloon-borne telescopes is high, with research groups typically having to shoulder part of the infrastructure development as well. Aiming to ease access to balloon-based observations, we present the efforts towards a community-accessible balloon-based observatory, the European Stratospheric Balloon Obser...
In this paper, we propose the implementation of a small refractor telescope inside a 2U-cubesat. ... more In this paper, we propose the implementation of a small refractor telescope inside a 2U-cubesat. The satellite will carry out photometric studies of nearby bright stars aiming the monitoring of exoplanet transits. The telescope consists of an achromatic 80mm-diameter lens working at f/5 coupled to a 1600 × 1220 CCD camera. Resulting images will be sent to the ground using an FM transmitter, operating at a frequency of 437.465MHz and at a rate of 9600 bps. The 2U-cubesat includes an attitude control system which consists of a 3-axis mechanical gyroscope in turn composed of 6 engines acting as reaction wheels. The maximum power consumption of the full system is around 15 Watts. A GPS installed in the communication system will provide the satellite location coordinates. In addition, an optical 8-inch telescope, with f/10 focal ratio, will be used for tracking the satellite from ground.
4 paginas, 7 figuras.-- Trabajo presentado al 25 Simposium Nacional de la Union Cientifica Intern... more 4 paginas, 7 figuras.-- Trabajo presentado al 25 Simposium Nacional de la Union Cientifica Internacional de Radio (URSI) en la sesion III: Antenas III, celebrado en Bilbao (Espana) del 15 al 17 de septiembre de 2010.
Los cansat son conocidos en casi todo el mundo. Su principal objetivo es transmitir a los estudia... more Los cansat son conocidos en casi todo el mundo. Su principal objetivo es transmitir a los estudiantes universitarios los conceptos basicos de diseno y construccion de satelites artificiales. La mayoria de las universidades mas importantes de diversos paises que cuentan con una facultad de ingenieria y ciencias exactas han construido al menos uno de estos dispositivos como actividad extraescolar para sus alumnos, mediante cursos, talleres o a traves de los programas de capacitacion que las agencias espaciales ofrecen para captar las futuras generaciones de ingenieros y cientificos en el area espacial (Walker et al., 2010).
Stratospheric balloons offer accessible and affordable platforms for observations in atmosphere-c... more Stratospheric balloons offer accessible and affordable platforms for observations in atmosphere-constrained wavelength ranges. At the same time, they can serve as an effective step for technology demonstration towards future space applications of instruments and other hardware. The Stratospheric UV Demonstrator of an Imaging Observatory (STUDIO) is a balloon-borne platform and mission carrying an imaging micro-channel plate (MCP) detector on a 0.5 m aperture telescope. STUDIO is currently planned to fly during the summer turnaround conditions over Esrange, Sweden, in the 2022 season. For details on the ultraviolet (UV) detector, see the contribution of Conti et al. to this symposium. 1 The scientific goal of the mission is to survey for variable hot compact stars and flaring M-dwarf stars within the galactic plane. At the same time, the mission acts as a demonstrator for a versatile and scalable astronomical balloon platform as well as for the aforementioned MCP instrument. The gondola is designed to allow the use of different instruments or telescopes. Furthermore, it is designed to serve for several, also longer, flights, which are envisioned under the European Stratospheric Balloon Observatory (ESBO) initiative. In this paper, we present the design and current status of manufacturing and testing of the STUDIO platform. We furthermore present the current plans for the flight and observations from Esrange. 1. STATE OF THE ART IN BALLOON-BORNE ASTRONOMY The idea of using stratospheric balloons to overcome the opacity of Earth's atmosphere for astronomical observations is not new. Historically, the advantages were obvious: spacecraft did not exist or were hardly available and capabilities of airplanes were limited, leaving balloons as the only option to move instruments above most of the atmosphere. Nowadays, the benefits do not seem as clear: both spacecraft and airplanes provide powerful observation platforms and ground-based telescopes invest large efforts into compensating atmospheric influences. However, even in the era of nano-and microsatellites, space observatories are intrinsically expensive and bear operational limitations: development times are long, updates or corrections of the instrumentation are usually not possible after launch, and consumables, such as cryogenic coolant fluids, cannot be refilled or replaced, as seen with the Herschel Space Observatory. Furthermore, rather conservative approaches towards new technologies are used to minimize risks of expensive failure. Ground-based and airborne telescopes, on the other hand, still suffer from fundamental limitations imposed by the atmosphere at certain wavelengths. On the other hand, technological advances have made balloon-borne telescopes more attractive over the last couple of years. These particularly include more reliable balloons and the opening of long-duration flight routes, allowing flight durations of 30 to 40 days on "conventional" long duration routes and promising 50 to 100 days on ultra long duration routes. Consequently, the last couple of years saw an increase of balloon-astronomy initiatives aiming at more regularly
International Journal of Antennas and Propagation, 2017
We propose a model of antenna-coupled microbolometer to be included in an array for receiving and... more We propose a model of antenna-coupled microbolometer to be included in an array for receiving and detecting long wave infrared (LWIR) electromagnetic radiation. The antenna is joined to microstrip bandpass filters thus forming a single metal structure to define the operation frequency band. The antenna and microstrip filters are modeled in aluminum thin film. The microbolometer is modeled with superconducting niobium, all together on a silicon nitride membrane. The squared pixel structure is designed on a support frame of 20 μm in size. Simulation results for this antenna exhibit a frequency range of operation from 27 to 35 THz and is configured for two arrays, one of 10×10 and the other one of 50×50 elements. The device has been simulated by means of the commercial electromagnetic software (HFSS), which is based on the finite elements method. The predicted values for the figures of merit of this microbolometer are as follows: τ=5.8 ns, Rv=5.3×103 V/W, and D⁎ = 2.07×1010 cmHz/W, res...
In this paper, we describe the process to construct a pico-satellite mounted in a bottle of polye... more In this paper, we describe the process to construct a pico-satellite mounted in a bottle of polyethylene terephthalate (PET) of 345 ml. The assembly and tests were made during the 6th CanSat Leader Training Program (CLTP-6) at University Hokkaido-Japan in the summer 2015. The pico-satellite was launched in the facilities of Uematsu Electric Co. Ltd. in Akabira-Japan by a paper model rocket, which achieved a height of approximately 100 m. The mission was designed to measure physical variables, such as temperature and humidity using electronic sensors. During the flight, we observed that the temperature inside the rocket was ∼0.5 • C higher than the temperature of the environment. We registered a humidity difference of ∼5%, measured between the maximum height and the landing point. The flight pattern was projected to a plane that covers an area of 50 m × 50 m by means the coordinates of a GPS.
This report presents two proposals of antenna designs suitable to be included in arrays for multi... more This report presents two proposals of antenna designs suitable to be included in arrays for multi-frequency operation in the ranges from ∼10 to ∼60 GHz and from ∼130 to 300 GHz, both aimed to be applied in Cosmic Microwave Background (CMB) experiments. The antennas exhibit small sizes and wide bandwidth approaching 131% and 79% respectively. The radiation characteristics for a single element and the total directivity for configurations of 5x5 and 15x15 elements array were simulated by means of HFSS (Ansoft) software.
We propose a pixel design, aimed to be included in an array, receiving and detecting simultaneous... more We propose a pixel design, aimed to be included in an array, receiving and detecting simultaneously two bands of the Cosmic Microwave Background (CMB). It is composed of a bowtie antenna, feeding a diplexer structure to separate the signal towards two bolometric detectors at 150 and 220 GHz. The diplexer makes use of differential transmission lines of Coplanar Striplines (CPS) and Broadside Coupled Lines (BCL) types, for filtering and separation purposes. The antenna and diplexer are planned to be fabricated in a superconductive niobium thin film deposited on a Silicon substrate, while NbSi bolometers will lie on a SiN membrane. The device has been simulated by means of ADS (Agilent), CST Microwave Studio and HFSS (Ansoft) softwares. Final dimensions that take into account the kinetic inductance of the superconducting lines are proposed. Promising computation results are found, with signal separation up to 20 dB.
We propose a bow-tie slot antenna fed by a microstrip to CPW transition to operate in the mm wave... more We propose a bow-tie slot antenna fed by a microstrip to CPW transition to operate in the mm wave-band from 29 to 45 GHz. The measured results exhibit a maximum impedance bandwidth of 43% for VSWR<2, and an average gain of 10 dB. The antenna is suitable for the integration with microstrip circuits and mm-wave MMIC. The antenna is mounted on a mechanical structure with a movable reflector plane which provides the adjustment for the return losses. The whole design facilitates the cooling process when this antenna is used in low temperature experiments.
This paper describes the impact of the Planck Low Frequency Instrument front end physical tempera... more This paper describes the impact of the Planck Low Frequency Instrument front end physical temperature fluctuations on the output signal. The origin of thermal instabilities in the instrument are discussed, and an analytical model of their propagation and impact on the receivers signal is described. The experimental test setup dedicated to evaluate these effects during the instrument ground calibration is reported together with data analysis methods. Finally, main results obtained are discussed and compared to the requirements.
Progress In Electromagnetics Research Letters, 2011
Measurements of the radiation patterns from a planar array of bow-tie slot antennas coupled throu... more Measurements of the radiation patterns from a planar array of bow-tie slot antennas coupled through an extended hemispherical lens are reported. The design operates over 10% bandwidth centred at 30 GHz with a return loss of 10 dB. A moderate directivity from the integrated lenses of 13 dB with half-power beamwidth (HPBW) of 10 • is achieved. The reduced size of this design is suitable for the integration with millimetre wave circuits.
This paper describes an experimental setup for the spectral calibration of bolometric detectors u... more This paper describes an experimental setup for the spectral calibration of bolometric detectors used in radioastronomy. The system is composed of a Martin-Puplett interferometer with two identical artificial blackbody sources operating in the vacuum mode at 77 K and 300 K simultaneously. One source is integrated into a liquid nitrogen cryostat, and the other one into a vacuum chamber at room temperature. The sources were designed with a combination of conical with cylindrical geometries thus forming an orthogonal configuration to match the internal optics of the interfermometer. With a simple mathematical model we estimated emissivities of ε $ 0:995 for each source.
ABSTRACT We carried out measurements of thermal conductance and thermal contact resistance of two... more ABSTRACT We carried out measurements of thermal conductance and thermal contact resistance of two materials commonly used in low temperature laboratories such as an Electro-Magnetic Interference (EMI) Filter and Stycast 2850 FT epoxy. Both samples were attached on a heat sink made of oxygen-free high thermal conductivity (OFHC) copper and characterized at temperatures between 0.3 K and 4.5 K, using a 3He refrigerator mounted on a pumped 4He cryostat. For the EMI filter we applied a varied input power from 0.25 up to 50 μW to the heater which is soldered to its central pin, whereas for a thin layer of Stycast sandwiched between a copper strap and the heat sink we applied an input power from 10 up to 810 μW. The temperature dependences obtained in each case were $K=3\,{\cdot}\,10^{-5}T^{2.3}~[\frac{\mathrm{W}}{\mathrm{K}}]$ , and $R_{K}=8.4\,{\cdot}\,10^{-3}T^{1.7}\ [\frac{\mathrm{W}}{\mathrm{cm}^{2}\,\mathrm{K}}]$ respectively.
We describe a simple and efficient improvement to the Martin-Puplett interferometer, built at the... more We describe a simple and efficient improvement to the Martin-Puplett interferometer, built at the Max-Planck Institute for Radioastronomy in Bonn. Interferograms with its corresponding spectra taken with the interferometer operating in the vacuum mode, have confirmed that the detector's signal increases up to $10% when the microwave foam absorbers used as radiation sources are replaced by blackbody cavities.
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Papers by Angel Colin