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Know the basic structure of the ionosphere: D,
E and F layers and their order.
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Understand that ionisation is caused mainly by ultraviolet
rays from the sun.
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Knowthat the level of ionisation changes with the
time of day, the time of the year, and according to the 11-year sunspot cycle.
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Know that the sunspot number is an indicator of solar
activity.
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Know that the more sunspots gives better HF propagation
as a result of increased ionisation.
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Know that reflection from the F layer is the main
mode of HF propagation.
-
Know the meaning of ground wave, sky wave, skip
distance, and skip zone (dead zone).
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Know that high atmospheric pressure can cause ducting
in the troposphere, which increases the range of VHF and UHF signals.
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Know that the range of VHF signals can occasionally
be significantly increased by reflection from highly ionised areas in the
E layer (Sporadic E).
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Know that VHF and UHF signals normally pass through
the ionosphere, and at these frequencies propagation is within the troposphere
situated below the ionosphere.
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Know that snow, ice and heavy rain can attenuate signals
at UHF and above.
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Know and be able to manipulate the formula
v=fxl.
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Be able to calculate frequency or wavelength given
the other parameter.
