below the radar
In a position in which someone or something will remain unnoticed or undetected. With so many different amendments to the bill being made, some appropriations slipped below the radar. I plan to stay below the radar until this controversy blows over.
below/under the ˈradar (screen)
if something is below/under the radar, people are not aware of it: The conflict has slipped below the radar screens of the mass media.Experts say a lot of corporate crime stays under the radar.