under the radar

under (the/one's) radar

Without being noticed, detected, or addressed. A: "Have you heard this band's latest album?" B: "I didn't even know it was out, it must have flown under my radar." Every year, the government promises to do something about the homelessness problem, yet every year it seems to slip under the radar again.
See also: radar

under 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 under the radar. I plan to stay under the radar until this controversy blows over.
See also: radar
Farlex Dictionary of Idioms.

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.
See also: below, radar
Farlex Partner Idioms Dictionary

under the radar

Describing an action that cannot be detected. The term comes from aviation during World War II, where a plane is flying too low to be detected by the enemy’s radar. It soon was transferred to other situations, as in “I don’t want anyone to know I’m looking for another job, so keep my applications under the radar.” John Lescroart used it in A Plague of Secrets (2010), “Now I know . . . it hasn’t been the subject of much police concern so far . . . So up to now you’re all under the radar.”
See also: radar
The Dictionary of Clichés by Christine Ammer
See also:
  • fly beneath (the/someone's) radar
  • fly under (the/someone's) radar
  • under (the/one's) radar
  • beneath (the/someone's) radar
  • catch the eye
  • out of place
  • one-day wonder
  • a one-day wonder
  • a seven-day wonder
  • seven-day wonder