How does an antenna transmit radiation?

An antenna transmits radiation primarily through the use of alternating currents. When an alternating current flows through the antenna, it creates time-varying electric and magnetic fields. These fields then propagate away from the antenna as electromagnetic waves, or radiation. The essential aspect here is that the frequency of the emitted radiation corresponds to the frequency of the alternating current; as the current switches direction, it generates variations in the electromagnetic fields, leading to the emission of energy in the form of radio waves.

The relationship between the frequency of the current and the frequency of the radiation is fundamental. Specifically, the emitted radiation's frequency is directly proportional to how quickly the current alternates, which is why an antenna can be designed to operate at specific frequencies by controlling the current.

In this case, using a constant direct current would not produce electromagnetic radiation, as direct current flows in a single direction without oscillation. While resonating at a fixed frequency might occur in some antenna designs, it doesn't fully capture the dynamic nature of how alternating currents operate. Lastly, employing a sudden discharge of energy does not accurately describe the continuous process of radiation emission through alternating current; such discharges could potentially create transient signals rather than sustained radiation typical of continuous antenna operation.