Which statement characterizes the near field around an antenna?

Which statement characterizes the near field around an antenna?

• A. The fields propagate as plain, traveling waves.
• B. The near field around an antenna is purely electric.
• C. The near field stores no energy.
• D. The fields are non-propagating and exist in a complex temporal and spatial pattern.

Answer: (D)

In the near field around an antenna, the energy doesn’t travel away as a simple wave. Instead, electric and magnetic fields store energy and exchange it with the antenna’s current, creating reactive fields. These fields vary with time and position in a way that isn’t a straightforward traveling wave, leading to a complex temporal and spatial pattern. That’s why the near field is described as non-propagating and having a complex pattern. The other statements don’t fit: near-field behavior isn’t purely electric since both E and H are present; it does store energy in the reactive fields rather than none; and traveling waves characterize the far field, not the near field.

In the near field around an antenna, the energy doesn’t travel away as a simple wave. Instead, electric and magnetic fields store energy and exchange it with the antenna’s current, creating reactive fields. These fields vary with time and position in a way that isn’t a straightforward traveling wave, leading to a complex temporal and spatial pattern. That’s why the near field is described as non-propagating and having a complex pattern. The other statements don’t fit: near-field behavior isn’t purely electric since both E and H are present; it does store energy in the reactive fields rather than none; and traveling waves characterize the far field, not the near field.