For many of us it helps to put a personality to electrons. These little fellows don't like to get too close together. Being negatively charged they repel each other. They do like to keep in motion never stopping to rest. When these little fellows flow or move fast in a given direction they produce a magnetic field perpendicular radiating out from the direction of flow. Use the left-hand rule, thumb pointing in the direction of flow, curled fingers point in the direction of magnetic flow lines. Thus an antenna can transmit an electromagnetic energy flow just by having a bunch of these little fellows (electrons) running back and forth in a conductor. The transmitter circuit is then designed to cause this to happen by giving these little fellows energy and telling them how far to run back and forth (frequency).
EMP electromagnetic pulse is caused by a lot of charged particles moving in a given direction as occurs in lightning, nuclear explosions, etc. This causes a big magnetic pulse that radiates out and when it passes over something that is a conductor (has free electrons that can flow) gives some of it's energy to the electrons and causes them to flow. This can ultimately cause so much pressure at the end of the conductor that a spark can occur or damage can occur especially to sensitive circuits. Radios, TVs, communications equipment, etc. that have antenna and sensitive input circuits are especially susceptible to this type of damage.
Offered by Mike.