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