Physics, Astronomy and Electronics Work Bench Callisto Spectrum Measurements in Via Mala, Switzerland

Abstract. This report documents part of a planned measurement campaign in which spectrum measurements were done at different locations in the mountains in Switzerland. The results of a study in Via Mala Gorge carried out in August 2007 are presented and compared with Bleien observatory. The spectrum measured in a Gorge are expected to have reduced low frequency RFI due to refraction around the high gorge walls, and Via Mala was chosen as a test site as it is easily accessible. Measurements were carried out with a broadband omni-directional antenna connected to a Callisto spectrometer designed and built in ETH Zurich (Benz, 2004). This study indicates that the interference in the gorge is not significantly lower than otherwise in the frequency range below 1GHz (λ>30cm), thus Via Mala is not ideal for broadband spectroscopic solar radio astronomy observations. It also suggests that the reduction of interference within natural cavities in general is not very significant. Key words. Callisto, spectrum, cross modulation, inter-ference reduction