under (the/someone's) radar(redirected from under their radar)
under (the/someone'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