The Basic lessons · Radio wave propagation · B-007-002

How the Ionosphere Shapes Radio Signals

Learn how sunlight creates a charged layer in the sky that reflects radio waves. Understand why some bands work for long distances only at night while others fail during the day.

This lesson is part of SignalPrep Pro. The subsection's 11 exam questions are free to practise: practise B-007-002.

What this subsection asks

• What causes the ionosphere to form?
• What type of solar radiation is most responsible for ionization in the outer atmosphere?
• Which ionospheric region is closest to the Earth?
• Which region of the ionosphere is the least useful for long-distance radio-wave propagation?
• Which region of the ionosphere separates into two sub-regions in the daytime?
• When is the ionosphere most ionized?
• When is ionization at a minimum in the ionosphere?
• Why is the F2 region mainly responsible for the longest distance radio-wave propagation?
• What is the main reason the 160-metre and 80-metre bands tend to be useful only for short-distance communications during daylight hours?
• During the day, what two sub-regions appear in the ionosphere?
• What is the position of the E region in the ionosphere?