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.

The origin of some of the text on this page is from the RSGB with additions by the web master