The band normally used for Aeronautical Mobile Service (AMS) voice communication is defined between 118.000 and 136.975 MHz, which covers its use for commercial and general aviation, air traffic control and other uses.
The AMS refers to VHF and HF voice communication. The VHF propagation is practically straight-line propagation (similar to light waves). Therefore, the VHF propagation characteristics are ideal for short-distance terrestrial communication. When, due to shadowing (e.g. by a hill), VHF communication is not possible, it is still possible to communicate using the upper part of the HF band where the surface wave is of little use.
Channel spacing in the airband has been 25 kHz. However, increasing congestion has led to further subdivision into 8.33 kHz channels in the ICAO European region - this separation has become mandatory above FL195.
Frequency band | Frequencies | Wave band | Wave length | |
VLF | Very Low Frequency | 3-30 kHz | Very long | 100-10 km |
LF | Low Frequency | 30-300 kHz | Long | 10-1 km |
MF | Medium Frequency | 300-3000 kHz | Medium | 1 km-100 m |
HF | High Frequency | 3-30 MHz | Short | 100-10 m |
VHF | Very High Frequency | 30-300 MHz | Short | 10-1 m |
UHF | Ultra High Frequency | 300-3000 MHz | Ultra short | 1 m-10 cm |
SHF | Super High Frequency | 3-30 GHz (3000-30 000 MHz) | Super short | 10-1 cm |
EHF | Extremely High Frequency | 30-300 GHz | Extremely short | 1 cm-1 mm |
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