Basic Radio Wave Propagation

• Flight radiotelephony is the study and practical use of aircraft radio communication.
• In aviation, Very High Frequency (VHF) radio is commonly used for voice communications.

Radio Waves

Radio waves are a form of electromagnetic radiation.

• They do not require a medium in order to travel.
• They can travel through air and the vacuum of space.
• Radio waves travel at approximately the speed of light — 300,000 km/sec.
• Electromagnetic waves consist of changing electric and magnetic fields travelling outward from their source.
• These electromagnetic waves are used to transmit and receive radio signals.

A useful analogy is dropping a stone into a pond. Waves spread outward from the point where the stone enters the water, causing a floating object such as a cork to move up and down as the waves pass.

Frequency

Frequency is the number of complete wave cycles that pass a point in one second.

• Frequency is measured in Hertz (Hz).
• One Hertz equals one cycle per second.

Amplitude

Amplitude is the distance from the baseline of a wave to:

• the highest point of a peak; or
• the lowest point of a trough.