Which statement accurately describes the near field behavior?

Which statement accurately describes the near field behavior?

• A. The region very close to the antenna is where the fields are pure propagating waves.
• B. The near field contains only the electric field.
• C. The near field has uniform field patterns for all antennas.
• D. The near field is non-propagating and has a complex temporal-spatial pattern.

Answer: (D)

Near-field behavior involves energy that is stored in the field close to the antenna rather than carried away as a traveling wave. In this region, the electric and magnetic fields are often out of phase and exchange energy back and forth, so the fields do not form a simple propagating wave. The spatial distribution of the fields is highly dependent on the antenna’s geometry and orientation, leading to a complex, time-varying pattern rather than a uniform, repeating shape. Only at greater distances does the wave become a propagating radiation pattern with a more predictable, in-phase relationship between E and H. This combination of non-propagating energy storage and a complex spatial-temporal field structure is what the near-field describes.

Near-field behavior involves energy that is stored in the field close to the antenna rather than carried away as a traveling wave. In this region, the electric and magnetic fields are often out of phase and exchange energy back and forth, so the fields do not form a simple propagating wave. The spatial distribution of the fields is highly dependent on the antenna’s geometry and orientation, leading to a complex, time-varying pattern rather than a uniform, repeating shape. Only at greater distances does the wave become a propagating radiation pattern with a more predictable, in-phase relationship between E and H. This combination of non-propagating energy storage and a complex spatial-temporal field structure is what the near-field describes.