Radio waves (electromagnetic waves) used for radio, mobile phones, etc.; also used to refer to signal reception.
山間部では携帯の電波が届きにくいことがある。
In mountainous areas, mobile phone signals (radio waves) can be weak.
ラジオの電波を合わせて、好きな局を探した。
I tuned the radio waves to find my favorite station.
電波干渉が起きて受信が途切れることがある。
Interference with radio waves can cause reception to drop out.
(Slang) Refers to strange, bizarre, or outlandish statements or ideas—saying someone is 'on the wavelength' (weird). Common in certain subcultures.
彼の話は時々電波で、何を言っているのか分からない。
His talk is sometimes so weird that I can't understand what he's saying.
あのアニメは電波系のネタが多く、マニアに人気がある。
That anime has a lot of offbeat (weird) jokes and is popular with fans.