Antenna Near Field Calculator

The near field region is close to the antenna where the electromagnetic field is reactive and complex. The far field region is where the field becomes purely radiative and the antenna pattern is well-defined. The transition depends on antenna size and wavelength.

For linear antennas, use the physical length. For dish antennas, use the diameter. For array antennas, use the largest overall dimension of the entire array structure.

The reactive near field extends from the antenna surface to a distance of λ/(2π). In this region, the electromagnetic field is predominantly reactive and energy storage dominates over radiation.

The radiating near field or Fresnel region extends from the reactive near field to 2D²/λ. In this region, the radiation pattern depends on distance and the field is transitioning from near field to far field characteristics.

The far field distance (greater than 2D²/λ) is where antenna measurements should be taken for accurate pattern characterization. Beyond this distance, the antenna pattern is independent of measurement distance.

Higher frequencies result in shorter wavelengths, which typically reduce the distances of all field regions. Lower frequencies extend these regions further from the antenna.

For antennas where D < λ/2, there are only two regions: near field and far field. The radiating near field region effectively doesn't exist for electrically small antennas.

Yes, this calculator applies to all antenna types including dipoles, patches, dishes, arrays, and horns. Just use the largest physical dimension of your specific antenna.