Far-Field Distance Calculator
Far-field boundary 2D²/λ and reactive near-field boundary λ/2π from frequency and maximum antenna/EUT dimension.
Worked example
Input: Frequency 1000 MHz, Max. antenna/EUT dimension D 0.3 m
Result: Wavelength λ 0.299792 m, Far-field boundary 2D²/λ 0.600415 m, Reactive near-field boundary λ/2π 0.0477135 m
Result: Wavelength λ 0.299792 m, Far-field boundary 2D²/λ 0.600415 m, Reactive near-field boundary λ/2π 0.0477135 m
Formula
R_far = 2·D² / λ
R_react = λ / (2π)
How it works
The far-field boundary is usually estimated as 2D²/λ. Inside it, the E/H ratio and distance dependence differ from plane-wave assumptions. It tells you which region you are measuring in when choosing a test distance, using near-field probes or calibrating antennas.
Practical tip2D²/λ assumes D is large compared with the wavelength. For small sources at low frequencies also check λ/2π, and conservatively use the larger of the two.
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Results and summaries are for reference. For certification and test reports use the latest official standard text and calibrated instrument data. Last updated: 2026-10-10