This calculator determines the reactive near field, radiating near field (Fresnel region), and far field distances for an antenna, based on its largest dimension and operating frequency. These distances help engineers understand where field strength and wave behavior transition between regions.
Formulas
λ = c / f
Reactive Near Field = 0.62 * √( D³ / λ )
Radiating Near Field = 2 * D² / λ
Far Field = 2 * D² / λ
Formula Explanation
- λ = Wavelength (m), where c = 3×10⁸ m/s and f = frequency (Hz).
- D = Largest dimension of the antenna (m).
- The near and far field zones define where the radiated field behaves differently in terms of amplitude and phase.
Example
Input: D = 1 m, f = 3 GHz
Result: Far Field ≈ 20 m
Who uses it
Useful for RF engineers and antenna designers to identify accurate measurement zones and ensure valid far-field testing conditions.