What is the function of an antenna in electronics?

• A. Device that stores electrical energy
• B. Device that converts electrical energy into mechanical motion
• C. Device that converts electrical power into radio waves
• D. Device that measures current

Answer: (C)

An antenna’s job is to couple electrical energy to the electromagnetic field and make radio waves, or to do the reverse and convert incoming radio waves back into electrical signals. When transmitting, an alternating current at the chosen radio frequency makes charges in the antenna accelerate, creating changing electric and magnetic fields that radiate away as radio waves. When receiving, incoming radio waves induce current in the antenna, which a receiver then senses and processes. This is distinct from devices that store energy (capacitors/inductors), move things mechanically (motors/actuators), or measure current (ammeters).