Some basic definitions:
- wavelength: linear measurement of a wave in meters
- cycle: peak to peak vibration period measured in seconds
- frequency: number of cycles per second measured in hertz
Wavelength remains constant, but the amplitude (strength) decreases with distance from the transmitting station.
Frequency Bands:
- Low and Medium Frequency (LF / MF): NDBs
- High Frequency (HF): long range communication
- Very High Frequency (VHF): communication, VOR, ILS
- Ultra High Frequency (UHF): DME, glideslope of ILS
Characteristics:
- LF/MF/HF
- ground waves: follow the surface of the earth; can bend and be attenuated (higher frequencies = more attenuation = less reception distance)
- sky waves: travel up into the atmosphere and are reflected back to earth from the ionosphere
- skip distance: the distance between the transmitting antenna and the point where the skywave first returns to the surface of the earth
- skip zone: the space between the end of ground wave coverage and the point at which the first sky wave is returned to earth
- VHF
- line of sight
Comm and nav systems will get their own separate posts soon - stay tuned!
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