How do the E and H fields behave when radiated from an antenna?

The correct answer is that the electric (E) and magnetic (H) fields are out of phase when radiated from an antenna. In electromagnetic wave propagation, the E and H fields oscillate perpendicular to each other and to the direction of wave travel. When an antenna transmits, the alternating current flowing through the antenna creates the E field, and this changing electric field induces the H field.

The key characteristic of these fields is their phase relationship. While both fields are produced by the same radiating source, they do not reach their maximum and minimum values simultaneously. The E field reaches its peak at a certain point in time, followed by the H field reaching its peak at a different point in time, establishing a phase difference of 90 degrees between them. This out-of-phase relationship is fundamental to the nature of electromagnetic waves, contributing to their ability to propagate through space.

Understanding this relationship is crucial in fields such as antenna theory and electromagnetic wave propagation, where the interaction and alignment of these fields affect the efficiency and characteristics of the transmitted signal.