RF IN THE ENVIRONMENT
As you have already learned, RF signals are either on a conductor or flying around as waves in the air. When an RF signal is on a conductor, which is just about any piece of metal, it only hangs out on the surface of the metal object itself. Picture a solid piece of metal the shape of a brick. If an RF signal were placed on the brick, the signal itself would only be present on the surface of the brick, none would venture inside. If a detector could somehow be placed inside the brick, it would not detect the presence of the RF signal. This behavior exhibited by RF signals is called the skin effect, which is self-explanatory.
The reason the skin effect occurs is simple to understand, if you have ...