What frequencies do the three ILS components use?

What frequencies do the three ILS components use?

• A. Localizer uses VHF (108.10 to 111.95 MHz); Glideslope uses UHF (329.15 to 335.0 MHz); Marker beacons use 75 MHz
• B. Localizer uses UHF; Glideslope uses VHF; Marker beacons use 100 MHz
• C. Localizer uses 75 MHz; Glideslope uses UHF; Marker beacons use UHF
• D. Localizer uses 50 GHz; Glideslope uses 50 GHz; Marker beacons use 75 MHz

Answer: (D)

Understanding how ILS signals are separated by frequency helps you see why these components are paired with their bands. The Localizer operates in the VHF range, roughly 108.10 to 111.95 MHz, providing lateral guidance. The Glideslope uses the UHF range, about 329.15 to 335.0 MHz, for vertical guidance. Marker beacons sit at 75.0 MHz to mark approach points. These distinct bands keep the signals from interfering with one another. Frequencies like 50 GHz are far outside the ILS bands and not used for any ILS component.

Understanding how ILS signals are separated by frequency helps you see why these components are paired with their bands. The Localizer operates in the VHF range, roughly 108.10 to 111.95 MHz, providing lateral guidance. The Glideslope uses the UHF range, about 329.15 to 335.0 MHz, for vertical guidance. Marker beacons sit at 75.0 MHz to mark approach points. These distinct bands keep the signals from interfering with one another. Frequencies like 50 GHz are far outside the ILS bands and not used for any ILS component.