| （英） |
We have been developing a small transmitting power 76 GHz millimeter-wave radar system for helicopter obstacle detection. The purpose of the on-board radar is to detect and avoid obstacles such as high-voltage power lines and pylons that may affect flight safety. This paper studies the detection performance of the 76 GHz millimeter-wave radar system in rainfall conditions. We discuss the capability of our helicopter obstacle detection system during bad weather conditions. First, we show estimated rain attenuations in 76 GHz based on ITU-R document. Second, we discuss the detection performance of the 76 GHz millimeter-wave radar system in several rain conditions. From the results, we can see that the estimated maximum detection range for 0.25 mm/h (Drizzle), 2.5 mm/h (Light rain) and 5.0 mm/h (Medium rain) are 2300 m, 1950 m, and1700 m, respectively. As helicopters are operated with visual flight rules (VFR), this radar system is practically used under drizzle or light rain conditions only. Therefore, our fabricated millimeter-wave radar system has about 2 km detection range in the practical conditions. Finally, we show the estimated radar plan position indicator (PPI) scope based on field experiment data. While there are many reflections visible from terrestrial objects, such as trees and buildings, the positions of the power pylons and lines are visible even in medium rain conditions at 840 m. |