A 380 GHz SIS receiver using Nb/AlO(x)/Nb junctions for a radioastronomical balloon-borne experiment: PRONAOS

The superheterodyne detection technique used for the spectrometer instrument of the PRONAOS project will provide a very high spectral resolution (delta nu/nu = 10(exp -6)). The most critical components are those located at the front-end of the receiver: their contribution dominates the total noise of the receiver. Therefore, it is important to perform accurate studies for specific components, such as mixers and multipliers working in the submillimeter wave range. Difficulties in generating enough local oscillator (LO) power at high frequencies make SIS mixers very desirable for operation above 300 GHz. The low LO power requirements and the low noise temperature of these mixers are the primary reason for building an SIS receiver. This paper reports the successful fabrication of small (less than or equal to 1 sq micron) Nb/Al-O(x)/Nb junctions and arrays with excellent I-V characteristics and very good reliability, resulting in a low noise receiver performance measured in the 368/380 GHz frequency range

Radiomètre en ondes millimétriques pour l'étude de l'atmosphère. Utilisation d'éléments quasi-optiques

Nous présentons un système radiométrique en ondes millimétriques pour l'étude des raies atmosphériques de l'oxygène et de la vapeur d'eau situées entre 100 et 200 GHz. Après une description du principe du radiosondage, les divers éléments du récepteur sont exposés. L'accent est porté sur les tehniques quasi-optiques utilisées : filtre, interféromètre, rotateur de polarisation

Radiomètre en ondes millimétriques pour l'étude de l'atmosphère. Utilisation d'éléments quasi-optiques

We present a millimeter-wave radiometric system to study oxygen and water vapor atmospheric lines between 100 and 200 GHz. After a description of the remote sensing principle, we describe some elements of the receiver. The quasi-optical part of the receiver is emphasized : filter, interferometer, polarization rotator.Nous présentons un système radiométrique en ondes millimétriques pour l'étude des raies atmosphériques de l'oxygène et de la vapeur d'eau situées entre 100 et 200 GHz. Après une description du principe du radiosondage, les divers éléments du récepteur sont exposés. L'accent est porté sur les tehniques quasi-optiques utilisées : filtre, interféromètre, rotateur de polarisation

Laboratory dielectric constant determination for planetary surface characterization

EPSC-DPS2011-1083-1A program of dielectric constant determination on various analogues, over a large range of frequencies and porosities, is under development in relation with the interpretation of Rosetta spacecraft observations. The analogues are meteoritic samples (compact and powdered), likely to be representative of the asteroids that have already been flown-by and of the cometary nucleus that is to be encountered. First results have already been obtained for asteroid Steins

Laboratory measurements of dielectric properties of compact and granular materials, in relation with Rosetta mission.

The European Rosetta spacecraft (s/c), launched in 2004, will be the first s/c to orbit a comet and place a lander module on its surface. In 2014, the s/c will rendezvous with the comet 67P/Churyumov-Gerasimenko and place the lander on its surface thereby allowing in situ and remote sensing of the comet nucleus. Two radio experiments, one passive (MIRO [1]) and one active (CONSERT [2]), are aboard the Rosetta s/c. MIRO, composed of two radiometers, with center band frequencies at 190 GHz and at 563 GHz to determine the brightness temperatures of the target surfaces and sub-surfaces, has already observed asteroids (2867) Steins [3] and (21) Lutetia [4]. CONSERT will investigate the deep interior of the nucleus using 90 MHz radio-waves transmitted from the orbiter through the nucleus and returned to the orbiter from the lander. To support interpretations of MIRO and CONSERT observations, a program of dielectric properties measurements is under development on a large range of frequencies encompassing those of the above-mentioned experiments. Several instruments for dielectric constant determination are available at IMS laboratory (Bordeaux, France): impedance analyzer, coaxial sensor, resonant cavities (measuring respectively at 100 MHz, 0.5-6 GHz, 1.2-13.4 GHz). Millimeter benches are available at both IMS and LERMA laboratories (measuring respectively at 30-110 GHz and 70-230 GHz). Taking into account the possible presence of regolith layers on the surface of asteroids or nuclei and the very low density of cometary nuclei [5], the dependence of the dielectric constant on the structure and porosity of given granular materials needs also to be investigated (while the thermal and hygrometric conditions are carefully monitored). We have already reported measurements obtained on various meteorites, possibly representative of some asteroid surfaces [6, 7]. We will also report systematic measurements obtained on a large sample of pyroclastic deposits from Etna, providing different sizes distributions (i.e. surface to volume ratios), and possibly porosities. Dielectric constant determination at 190 GHz typically suggests that the real part of dielectric constant slowly increases with grain size: 2.86 ± 0.06, 2.96 ± 0.02 and 3.13 ± 0.05 for sizes respectively lower than 50 µm, between 50 and 160 µm and between 160 and 355 µm. Additional series of measurements on compact and granular samples of meteoritic analogues, such as carbonaceous chondrites are also to take place

Laboratory measurements of dielectric properties of compact and granular materials, in relation with Rosetta mission.

The European Rosetta spacecraft (s/c), launched in 2004, will be the first s/c to orbit a comet and place a lander module on its surface. In 2014, the s/c will rendezvous with the comet 67P/Churyumov-Gerasimenko and place the lander on its surface thereby allowing in situ and remote sensing of the comet nucleus. Two radio experiments, one passive (MIRO [1]) and one active (CONSERT [2]), are aboard the Rosetta s/c. MIRO, composed of two radiometers, with center band frequencies at 190 GHz and at 563 GHz to determine the brightness temperatures of the target surfaces and sub-surfaces, has already observed asteroids (2867) Steins [3] and (21) Lutetia [4]. CONSERT will investigate the deep interior of the nucleus using 90 MHz radio-waves transmitted from the orbiter through the nucleus and returned to the orbiter from the lander. To support interpretations of MIRO and CONSERT observations, a program of dielectric properties measurements is under development on a large range of frequencies encompassing those of the above-mentioned experiments. Several instruments for dielectric constant determination are available at IMS laboratory (Bordeaux, France): impedance analyzer, coaxial sensor, resonant cavities (measuring respectively at 100 MHz, 0.5-6 GHz, 1.2-13.4 GHz). Millimeter benches are available at both IMS and LERMA laboratories (measuring respectively at 30-110 GHz and 70-230 GHz). Taking into account the possible presence of regolith layers on the surface of asteroids or nuclei and the very low density of cometary nuclei [5], the dependence of the dielectric constant on the structure and porosity of given granular materials needs also to be investigated (while the thermal and hygrometric conditions are carefully monitored). We have already reported measurements obtained on various meteorites, possibly representative of some asteroid surfaces [6, 7]. We will also report systematic measurements obtained on a large sample of pyroclastic deposits from Etna, providing different sizes distributions (i.e. surface to volume ratios), and possibly porosities. Dielectric constant determination at 190 GHz typically suggests that the real part of dielectric constant slowly increases with grain size: 2.86 ± 0.06, 2.96 ± 0.02 and 3.13 ± 0.05 for sizes respectively lower than 50 µm, between 50 and 160 µm and between 160 and 355 µm. Additional series of measurements on compact and granular samples of meteoritic analogues, such as carbonaceous chondrites are also to take place

Coherent subterahertz radiation from femtosecond infrared filaments in air

International audienceWe report on what is believed to be the first observation of coherent subterahertz (sub-THz) emission from a 1-m string in the atmosphere. The sub-THz pulse emitted by the filamentary structure from an intense IR femtosecond laser pulse is detected perpendicularly to the laser propagation axis by use of two heterodyne detectors at 94±1 and 118±1GHz . We describe the characteristics of this emission and show evidence of constructive interference between two separate strings

Microwave Sounding Of The Martian Atmosphere With Mambo

International audienc

Microwave Sounding Of The Martian Atmosphere With Mambo

International audienc

Microwave Sounding Of The Martian Atmosphere With Mambo

International audienc