Can a helicopter mask itself from radar? I have read somewhere that if a helicopter is traveling under 100 km/h and below 5 meters AGL then most radars will ignore it. From what I understand of this process, the radars can pick up things like cars and vehicles driving on the ground and thus need to ignore certain signals if they are traveling below a certain speed and height.

Is this actually the case, though? Does this also apply to military-grade radars?



Edit: This is not asking if a helicopter can fly under the radars coverage, but whether the helicopter can using techniques to notch its signal from being displayed as a contact on a radar operator's screen.
Note that for advanced radar systems, moving helicopters might always be distinguishable from cars and other objects, due to the fact that helicopters have moving rotors.

While I have no information on military systems, I know the systems by robinradar can separate drones from birds by using doppler shift techniques.

Doing this on an actual, full-size helicopter without rotor guards should be a lot easier than on a drone.

This means avoiding detection by moving slow and staying low might not work, unless you can stay out of the line of sight of the radar system.