PPL » Flight Radio » Basic Radio Propagation
2.2 Basic Radio Wave Propagation
Propagation is the transmission of motion, light, sound, etc. in a particular direction or through a medium.
2.2.2 Describe the basic characteristics of High Frequency (HF) and Very High Frequency (VHF) in terms of:
(b) surface interference;
(c) clarity of reception.
Flight Radio Telephony is the study of how to operate the aircraft's radio and navigation system.
In aviation we use two types of radio frequency:
- High Frequency (HF) and
- Very high Frequency (VHF).
- Radio waves are based in the low end of the electromagnetic spectrum.
- The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.
- The electromagnetic spectrum extends from low frequencies used for modern radio communication to gamma radiation at the short-wavelength (high-frequency) end, thereby covering wavelengths from thousands of kilometres down to a fraction of the size of an atom.
- Radio waves do not require a medium to work in. This means that they can travel not only through air and solid materials, but also through the vacuum of space, and travel at the speed of light (300,000,000 m/s)
- Electromagnetic (radio) waves propagate outward from a source by causing alternate increases and decreases in the electrical field and the magnetic field at the same time. We use changes in the electrical fields to send and receive out radio waves. Dropping a stone in a pond and watching a cork in the water move up and down on the resulting waves moving outwards is a good analogy for this.