VHF UHF Propagation

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Aurora

Ionospheric F2

The same mode of propagation as often occurs on HF. As intense ionization of the ionosphere's F2 layer is necessary, this mode only occurs during peak solar conditions around the maximum of the solar cycle, if at all, and only affects VHF Lo band up to perhaps the 6m band.


Ionospheric scattering

Meteor Scatter

Sporadic E

Trans-equatorial (TEP)

This mode of propagation occurs between two locations at roughly the same distance from the magnetic equator, directly north/south of each other. See the map below for the location of the magnetic equator. It affects all VHF and UHF bands, although less often as one moves up in frequency. While TEP is fairly common on VHF-Lo and the 6 meter band worldwide, 144 MHz and higher propagation is rare outside of the Americas for unknown reasons. TEP is more common during periods of high solar activity.

There are two types of TEP:

  • Type I: Occurs roughly between 2-7 pm local time, and supports VHF-Lo through the 6 meter band slightly higher.
  • Type II: Occurs roughly between 7-11 pm local time, supporting propagation through the 70 cm band.


Inclination-map.jpg


Tropospheric Ducting

Tropospheric scatter



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