Demonstration of a 25% bandwidth 520-680 GHz Schottky receiver front-end for planetary science and remote sensing

International audiencePlanetary atmospheres are rich in molecular species with spectral rotational and vibrational signatures in the millimeter and submillimeter frequency range. In particular, the 520-680 GHz frequency ranges offers access to a various amount of minor and major constituents of the atmosphere, including water vapour (H2O), carbon monoxide (CO), hydrogen cyanide (HCN), carbon monosulfide (CS) and their isotopes to derive temperature and wind velocities [1] or surface emissivity [2]. Recently, we have developed and manufactured the 560 GHz subharmonic mixer, showing the excellent performances in the 525-625 GHz frequency region with mixer noise temperature of about 870 K, around 30hf/kB [3]. In this paper we present an update and extensive measurement showing that the mixer's RF bandwidth can be extended up to 25% keeping the excellent performances. Assessment study of the radiometer modelling and Schottky junction parameter deviations will be presented. A best fit of the junction I/V allows to derive the main diode DC parameters retrofitted to analytical models such as [4]. We discuss efforts on implementation of large bandwidth receiver system, including solutions for local power across large bandwidth [5] or in complex systems using simultaneous molecular line observations [6]

Effects of UMTS cellular phones on human hearing: results of the European project EMFnEAR

The European project EMFnEAR was undertaken to assess potential changes in human auditory function after a short-term exposure to radiofrequency (RF) radiation produced by UMTS (Universal Mobile Telecommunication System) mobile phones. Participants were healthy young adults with no hearing or ear disorders. Auditory function was assessed immediately before and after exposure to radiofrequency radiation, and only the exposed ear was tested. Tests for the assessment of auditory function were hearing threshold level (HTL), distortion product otoacoustic emissions (DPOAE), contralateral suppression of transiently evoked otoacoustic emission (CAS effect on TEOAE), and auditory evoked potentials (AEP). The exposure consisted of speech at a typical conversational level delivered via an earphone to one ear, plus genuine or sham RF-radiation exposure produced by a commercial phone controlled by a personal computer. Results from 134 participants did not show any consistent pattern of effects on the auditory system after a 20-min UMTS exposure at the maximum output of the phone with 69 mW/kg SAR in the cochlea region in a double blind comparison of genuine and sham exposure. An isolated effect on the hearing threshold at high frequencies was identified, but this was statistically nonsignificant after correction for multiple comparisons. It is concluded that UMTS short-term exposure at the maximum output of consumer mobile phones does not cause measurable immediate effects on the human auditory syste