Helicopter collision avoidance sensors require all weather and day and night performance. Radar fulfills these conditions. To be able to see also cables and other small scale structures, millimeter wave radar is a favourite candidate for this task. To be able to develop adequate collision avoidance algorithms, a data base of relevant background signatures has to be available. Measurements with a 94 GHz high resolution radar have been conducted over wooded and rocky terrain. The paper describes the measurement set-up and gives representative results.
