Which term is an alternative name for the far zone?

Which term is an alternative name for the far zone?

• A. Far field
• B. Fraunhofer zone
• C. Focal zone
• D. Fresnel zone

Answer: (B)

In the far region from an antenna or aperture, the waves are effectively planar and the angular pattern stays constant with distance. This region is traditionally known as the Fraunhofer zone, a term rooted in diffraction studies, and it’s the standard alternative name used in antenna theory for the far field. It’s in this zone that the field can be described by the Fourier transform of the aperture distribution, which underpins the far-field radiation pattern. The other terms don’t fit this exact naming: the Fresnel zone is the near-field where wavefronts are curved and path differences across the aperture matter, and terms like “focal zone” aren’t standard for this context. While “far field” is a descriptive phrase for the same region, the canonical alternative name highlighted in many texts is Fraunhofer zone.

In the far region from an antenna or aperture, the waves are effectively planar and the angular pattern stays constant with distance. This region is traditionally known as the Fraunhofer zone, a term rooted in diffraction studies, and it’s the standard alternative name used in antenna theory for the far field. It’s in this zone that the field can be described by the Fourier transform of the aperture distribution, which underpins the far-field radiation pattern. The other terms don’t fit this exact naming: the Fresnel zone is the near-field where wavefronts are curved and path differences across the aperture matter, and terms like “focal zone” aren’t standard for this context. While “far field” is a descriptive phrase for the same region, the canonical alternative name highlighted in many texts is Fraunhofer zone.