A radio frequency band of short wavelengths (shortwave); radio waves used for long-distance communication and shortwave broadcasting.
短波ラジオで海外放送を聞くのが趣味だ。
I enjoy listening to overseas broadcasts on shortwave radio.
短波は夜間に電離層の反射で遠くまで届きやすい。
Shortwave tends to travel far at night due to ionospheric reflection.