When applying RF energy to the elements of an antenna, what is the phase relationship between voltage and current?

In the context of antennas and their interaction with RF (Radio Frequency) energy, the correct phase relationship is characterized by voltage lagging current by 90 degrees. This phenomenon occurs due to the reactive nature of the elements in the antenna, as they behave similarly to inductors at RF frequencies.

When RF current flows through the antenna, the changing magnetic field creates an induced voltage across the antenna elements. However, this voltage does not come into play instantaneously with the current. Instead, the current reaches its peak value before the voltage does, due to the inductive characteristics of the antenna elements. This results in the voltage being out of phase with the current, specifically lagging the current by 90 degrees.

This phase difference is significant in antenna design and performance, as it directly influences the antenna’s radiating characteristics and impedance. Understanding this relationship helps in optimizing antennas for efficient signal transmission and reception.