Non-directional beacons (NDB)s operate on low frequency and medium frequency bands 190–415 kHz and 510–535 kHz. The instrument landing system (ILS) glide path operates in the UHF range of 329.3–335.0 MHz with marker beacons at 75 MHz. Distance measuring equipment (DME) also uses UHF from 962 to 1150 MHz.[1]