radar
noun [ C ]
uk/ˈreɪdɑːr/ usbelow/under the radar (also below/under the radar screen)
if something is below or under the radar, people are not aware of it:
They were operating under the radar, selling their Web wares from some garage in Bakersfield.
Many private treatment centres are slipping under the radar screen of the medical authorities.
on/off the radar (also on/off the radar screen)
used to say that people do or do not know about something or that something is or is not important to someone:
He dropped off the political radar for nearly two decades.
Toy safety is definitely on consumers' radar.