radar
noun [ U ] uk/ˈreɪ.dɑːr/ us/ˈreɪ.dɑːr/
雷达
a system that uses radio waves to find the position of objects that cannot be seen
Other vessels in the area show up on the ship's radar (screen). 该船的雷达（屏幕）显示这一海域有其他船只。
Idioms
beneath the/someone's radaridiom 被忘记，被忽视
ignored or not noticed by someone or by people in general
For the first 8 years of its existence, the band stayed largely beneath the radar. 在乐队成立的前八年里，他们大部分时间都被人忽略。
Little local bars like this fly beneath the tourists' radar. 像这样的当地小酒吧一般都不会引起游客的注意。
on/off someone's radaridiom （某人）知道／不知道;（某人）想到／没想到
If someone or something is on your radar, you are/are not aware of them or have/have not thought about them.
She has been on my radar since her first novel came out, but I haven't read any of her books. 她第一部小说出版时我就注意到她了，但是我从来没看过她的作品。
Five years ago, having a child wasn't even on my radar. 五年前我根本没想到要孩子。
We recycle our waste, but what happens to it afterwards is completely off our radar. 我们回收垃圾，但是这之后发生了什么我们就一点都不知道了。