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Reference Utilities
RF Exposure Safety Calculator
Compute the controlled/uncontrolled MPE distance for a given transmit power and frequency.
01
Tool
EIRP (duty-averaged)79.6 W
MPE (uncontrolled)0.2000 mW/cm²
MPE (controlled)1.0000 mW/cm²
Min distance – uncontrolled178.0 cm (1.78 m)
Min distance – controlled79.6 cm (0.80 m)
Estimate only. Always follow FCC OET-65 or your national RF safety regulations.
02
How it works
The FCC OET Bulletin 65 defines Maximum Permissible Exposure (MPE) limits. For frequencies 30–300 MHz the uncontrolled MPE is 0.2 mW/cm²; for 300–1500 MHz it is f/1500 mW/cm². Effective radiated power (ERP) accounts for antenna gain and duty cycle. Safe distance d (cm) ≈ √(EIRP_mW / (4π × MPE_mW/cm²)).
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03
How to use
- Enter transmit power (W) at the antenna feedpoint.
- Enter antenna gain (dBi), operating frequency (MHz), and average duty cycle.
- Read the recommended controlled/uncontrolled minimum distances.
04
Frequently asked questions
Is this a substitute for a station evaluation?
No. It is an estimate. FCC requires all amateurs to perform a station RF exposure evaluation; use OET-65 tables for compliance.
What is duty cycle?
The fraction of time you're actually transmitting at peak power. SSB voice is ~20%; digital modes can be 100%.
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