What Does Waveguide Mean?
A waveguide is a structure that is used to guide electromagnetic waves such as radio waves and microwaves. It serves to channel radio waves in a specific dimension and in a specific shape, allowing them to travel longer distances from the source toward the antenna and to travel only in a predetermined area in order to avoid interference and collision with other waves. Waveguides often come in the form of hollow conductive metal tubes or pipes that vary in size and shape depending on the wave being propagated.
Techopedia Explains Waveguide
A waveguide is used to confine the wave to propagate in one dimension so that under ideal conditions the wave loses very little power during propagation, since if it is unguided it weakens with the distance from the source. The conductive metals used in creating waveguides have a small skin depth in order to ensure a large surface conductance, and because of the reflection at the walls of the waveguide, the waves become confined in the interior of the waveguide. The wave propagates through the waveguide in a zigzag pattern as it bounces from wall to wall.
Waveguides are essentially any structure that allows the propagation of waves such as the classic example of a taut wire propagating vibrations, like on the "string and tin-can" communication devices that kids play with. This is the same principle on how metal pipes deliver banging sounds throughout the house when hit.