This calculator determines the reactive near field, radiant near field (Fresnel region) and far field distances from the dimensions of the antenna and the operating frequency. It helps to understand the behavior of radiation and define the area where measurements or propagation are most accurate.
Formulas
λ = c/f
Reactive near field: R < 0.62 × √(D³ / λ)
Radiating near field (Fresnel): 0.62 × √(D³ / λ) ≤ R ≤ 2 × D² / λ
Far field (Fraunhofer): R > 2 × D² / λ
Explanation of formulas
Wavelength (λ) is calculated from the speed of light (c) divided by the frequency (f). The following formulas allow us to define the three zones around an antenna: the reactive near field where induction effects dominate, the Fresnel zone where the transition to radiation occurs, and the far field where the wave becomes plane and stable for measurements.
Uses of the calculator
- Identify the minimum distance for accurate measurements of a radiation pattern.
- Evaluate areas of interference or coupling between antennas.
- Optimize antenna placement in complex environments.
- Educational tool for understanding electromagnetic field regions.