Hi @HaoyuMa Sorry to get to this post late.
The TraceTreeDepth parameter in the RTX Radar configuration (as shown in the tutorial) directly controls the number of ray bounces. Setting "TraceTreeDepth": 1 in your radar configuration is the intended method to achieve one-bounce reflections.
I also noticed that you posted this topic as well: How to RTX ray tracing in isaac sim and I think it is already answered there.