Translation guide
The English word 'radar' refers to a system that uses radio waves to detect objects and measure their distance, speed, or direction. In Japanese, the loanword レーダー is the most common equivalent, used in both technical and everyday contexts. The term 電波探知機 is a more formal, technical alternative, while レーダ is a variant spelling. This guide covers how to express 'radar' naturally in Japanese.
Referring to the radar system or device itself, used for detection and tracking.
The most common and natural way to say 'radar' in Japanese. Used in everyday conversation, news, and technical contexts.
The plane didn't show up on radar.
The weather radar detected heavy rain.
A more formal, technical term literally meaning 'radio wave detector'. Used in official or military contexts, but less common in daily speech.
This vessel is equipped with the latest radar.
A variant spelling of レーダー, sometimes seen in technical documents or older texts. Not recommended for learners.
I will explain the principles of radar.
Expressing the idea of being unnoticed, undetected, or not receiving attention.
Means 'without attracting attention'. A natural way to convey 'under the radar' in the sense of doing something discreetly.
He works under the radar.
Means 'without being noticed'. Suitable for 'under the radar' when emphasizing stealth.
Literally 'doesn't come up as a topic'. Used when something is off the radar in terms of public discussion.
A direct translation of 'not caught on radar', used metaphorically. Understandable but less natural than the above options.
This is a literal translation and may sound awkward in some contexts. Use only when the radar metaphor is clear.
Expressing that someone or something has come to someone's attention or is being monitored.
Means 'to attract attention'. A natural way to say something is on people's radar.
That new actor suddenly appeared on everyone's radar.
Literally 'enter one's field of vision'. Used when something comes onto someone's radar in a monitoring or awareness sense.
Means 'to be marked' or 'to be watched'. Informal, often used when someone is on the radar of authorities or competitors.
He's on the police's radar.
English idioms like 'under the radar' or 'off the radar' do not translate directly into natural Japanese. Using レーダーの下に or similar literal phrases will sound strange. Instead, use the Japanese expressions provided that convey the same meaning of being unnoticed or out of attention.
He tries to stay under the radar.
They left the venue under the radar.
That issue was off the radar for a while.
His activities flew under the authorities' radar.
That company came onto our radar.