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