Which statement best describes the energy beaming from a transmitting antenna?

• A. The energy beaming from a transmitting or 'hot' antenna
• B. The energy stored in a battery
• C. The energy in the magnetic field
• D. The energy dissipated as heat

Answer: (A)

The energy beaming from a transmitting antenna is the energy radiated away as electromagnetic waves into space. When current in the antenna changes, it creates oscillating electric and magnetic fields that propagate outward at the speed of light, carrying energy with them. This radiated energy is described by the Poynting flux, the flow of energy per unit area carried by the electromagnetic fields. It’s not the energy stored in a battery, nor is it simply the energy in the magnetic field near the antenna, and it isn’t the energy lost as heat in the antenna. A transmitter is described as “hot” when it is actively radiating, which corresponds to this outward beamed energy.