Use this as a screening estimate
Use the calculator as a screening estimate for transmitter exposure and station layout. Keep people away from accessible RF sources whenever the exposure assessment is uncertain.
RF Exposure – Free-Space Estimate
Simplified far-field power-density estimate. Not a substitute for a full full regulatory compliance evaluation.
Inputs
Power density—
WARNING: This is a simplified free-space far-field estimate only. It does NOT replace a proper RF safety evaluation. It ignores near-field effects, ground reflection, antenna pattern, common-mode radiation, and local regulations (e.g. national RF exposure rules in the applicable jurisdiction). Use only as a rough educational tool.
Notes
S ≈ (P × G × duty) / (4 π r²) W/m²
Always consult the regulations that apply in your country (FCC OET-65 in the US, or the equivalent national rules). This calculator is not jurisdiction-aware. Height, ground reflection and antenna pattern matter.
Why a real exposure assessment differs
Real exposure depends on antenna gain, duty cycle, distance, near-field effects, enclosure, feedline routing and the applicable regulatory method.
What to verify for compliance
Use the current national rules and station-specific measurement guidance for final compliance decisions.
Use the estimate to screen a station layout
RF exposure estimation is a screening calculation intended to help an operator identify situations that deserve a closer look. The actual exposure near an amateur station depends on frequency, power, antenna type, distance, duty cycle, ground and surrounding structures, so a simplified free-space estimate cannot describe every installation. The most important practical inputs are the RF power, antenna gain, operating duty cycle and distance to the nearest person. Short distances and high-gain antennas deserve particular attention because the near-field region may not behave like the simple far-field model used by basic calculators. Use the result as an engineering estimate, then apply the exposure limits and assessment method required by the regulator in the country where the station operates. Reduce uncertainty by increasing separation, lowering power where appropriate and avoiding assumptions that an indoor or portable antenna behaves like an ideal point radiator. The calculator should support a documented assessment, not replace the applicable safety rules.