Propagation
VHF/UHF Propagation
- Normally communication is line of sight
- Tropospheric Propagation – refraction of waves increases
radio horizon to 1.15 times visual line-of-sight
- Sporadic E Reflection – reflection of waves off highly
ionised sections of the E Layer
- Auroral Reflection / Scattering – reflection of waves off
ionised regions at higher latitudes (Northern Lights)
- Meteor Scatter – reflection from the ionised trails left by meteors.
Brief contacts lasting from a few seconds to a minute or more
- Earth-Moon-Earth (EME) – reflection off the moon.
Maximum power, large antennas and the best receivers are needed
to overcome free space and reflection losses and cosmic noise