Radio Wave Propagation
Propagation of RF

The study of how EM waves travel and interact with matter can become extremely complex. However, there are several important simplifications that can be made to more easily study the properties of EM waves. Historically, these simplifications were developed for light waves, but they also apply to radio waves, microwaves, and the entire EM spectrum.

In a vacuum, 2.4 GHz microwaves travel at the speed of light. Once started, these microwaves will continue in the direction they were emitted forever, unless they interact with some form of matter. The geometric ray is used to signify that the microwaves are traveling in free space. Since WLANs are usually on earth, within the atmosphere, the microwaves are traveling in air, not in a vacuum. However, in the next section the student will see that this does not significantly change their speed.

Similar to light, when RF travels through transparent matter, some of the waves are altered. Therefore, the velocity of 2.4 GHz and 5 GHz microwaves also changes, as the waves travel through matter. However, the amount of alteration depends heavily on the frequency of the waves and the matter. In the next two sections, some of the phenomena that can affect WLAN radio waves as they travel through matter will be studied.