A non-directional beacon (NDB) or non-directional radio beacon is a radio beacon which does not include inherent directional information., Suunamatu raadiomajakas (NDB) ehk mittesuunaline raadiomajakas on raadiomajakas, mis ei sisalda olemuslikku suunateavet.

a low or medium radio navigation service transmitting signals whereby the pilot of a suitably equipped aircraft can determine bearings, 'home in' on, and/or track to or from the station