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What are the RF exposure limits for antennas?

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RF exposure from fixed and mobile antennas (used more than 20 cm from people) is assessed against maximum permissible exposure (MPE) limits expressed as power density or field strength. For the general public, the FCC limit is 0.2 mW/cm² from 30 to 300 MHz, f/1500 mW/cm² from 300 to 1500 MHz and 1.0 mW/cm² from 1.5 to 100 GHz, averaged over 30 minutes.[1] ICNIRP 2020 sets comparable reference levels (e.g., 10 W/m² from 2 to 300 GHz for whole-body averaging).[2]

How do you calculate a compliance distance?

In the far field, S = EIRP/(4πR²), so R = √(EIRP/(4πSlimit)). Example: 100 W EIRP at 1900 MHz (general-public limit 1.0 mW/cm² = 10 W/m²): R = √(100/(4π·10)) ≈ 0.89 m. OET Bulletin 65 gives conservative prediction methods, including ground-reflection factors.[3][1]

What are the occupational limits?

FCC occupational/controlled limits are five times higher than general-population limits over most of the range (e.g., 5 mW/cm² above 1.5 GHz) and are averaged over 6 minutes, applying to people aware of and able to control their exposure.[1]

Which standards exist?

The FCC limits derive from NCRP and IEEE recommendations; IEEE C95.1-2019 and ICNIRP 2020 are the current international safety standards, with ICNIRP widely adopted in Europe.[4][2]

Frequently asked questions

Are near-field calculations different?

Yes; far-field formulas can overestimate or underestimate very close to large antennas, so OET 65 methods or measurements are used.

Do amateur stations need RF exposure evaluation?

Yes; FCC rules require amateur licensees to evaluate exposure.

What is 1 mW/cm² in W/m²?

10 W/m².

References

Online sources accessed October 21, 2026; printed works cited by edition. See all sources.

  1. “47 CFR 1.1310 — Radiofrequency radiation exposure limits”. U.S. FCC, eCFR. current text.
  2. “Guidelines for Limiting Exposure to Electromagnetic Fields (100 kHz to 300 GHz)”. ICNIRP, Health Physics, vol. 118, no. 5, pp. 483-524. 2020.
  3. “OET Bulletin 65, Edition 97-01: Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields”. U.S. FCC Office of Engineering and Technology. August 1997.
  4. “IEEE Std C95.1-2019: IEEE Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic, and Electromagnetic Fields, 0 Hz to 300 GHz”. IEEE. 2019.
Categories: Regulations and safety