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Near/Far Field Calculators

Reactive near field, radiating near field, far field, and measurement-distance boundaries from frequency and antenna size.

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Inputs

Frequency (30 kHz to 110 GHz)

Unit

Largest antenna dimension, D (0.25 to 100 m)

Unit

For an efficient dipole, D = λ/2. For an efficient monopole, D = λ/4.

Reactive near field: r < λ / 2π
Radiating near field: r < 2D² / λ
Far field: r > 2D² / λ
Measurement far field: r_min = 2D² / λ + λ/4

Field Boundaries

Reactive near field

r < 0 m

The reactive field dominates over the radiating field.

Radiating near field

r < 0 m

The Fresnel-region upper boundary.

Far field

r > 0 m

The Fraunhofer-region lower boundary.

Measurement far field

0 m

Includes the AS/NZS 2772.2:2016 margin of λ/4.

Communications Fundamentals

You may be interested in reading more in Communications Fundamentals: Chapter 12.

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