In order to track particles within snow avalanches using a high resolution radar, an electronically amplifying radar reflector, known as Active Target (AT), is developed and characterized. The AT, in conjunction with additional in-flow sensors, allows to analyze the flow dynamics of snow avalanches at the particle level. All measurements took place
at the Nordkette mountain range above Innsbruck. The AT is analyzed and characterized including antenna aperture as well as the AT signal intensity change with radar range. Therefore calibration measurements of the static AT with different orientations at known locations were taken directly in the field of view of the mGEODAR radar. Initial tests for the moving AT scenario include roll measurements before the AT was directly placed into the avalanche. In addition to its primary function, the AT is used to calibrate the mGEODAR radar system itself by providing a known reference target to investigate ghost targets in the radar data due to internal hardware problems. The study confirms the functionality of the newly developed AT in combination with the radar device. However, the AT antenna’s polarization and aperture require alignment of the AT with the radar beam. The signal intensity of the AT is at 40 dB for larger ranges than 200m, indicating that the compensation of the geometric signal attenuation of the
radar works as expected. For lower ranges, the target appears with increasing intensities that causes widening of the normally discrete target peak in the radar data. This is of minor importance for the avalanche measurements at typical distances between 300m and 750m. Furthermore, those high intensity targets cause ghost targets at 207m and 412m in addition to the true target range. However, a comprehensive check of multiple radar settings does not reduce those mirror effects and the origin of ghost targets can not be identified.
