What changed
RF exposure and safety — edited Aug 31, 2026 by Unknown editor
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Since 2021 the FCC no longer gives amateur stations a categorical exemption from its radio frequency
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exposure limits. Every licensee must determine that their station complies, keep the reasoning where
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they can produce it, and redo it whenever the station changes materially. Nothing is filed with the
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FCC — but if a complaint reaches the Enforcement Bureau, "I never looked at it" is not an answer.
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## What the limits actually are
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The rules set maximum permissible exposure (MPE) in terms of power density and averaged over time,
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and they are stricter in two ways people find surprising:
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- **The general population limit is more restrictive than the occupational one.** You and your
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family may fall under either depending on who knows what: occupational limits apply only to people
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who are aware of the exposure and can act to limit it.
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- **The most restrictive frequencies are in the VHF range**, roughly 30–300 MHz, because the human
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body is resonant there. A 50 W 2 m station needs more thought than a 100 W 80 m station.
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- Averaging times are 6 minutes (occupational) and 30 minutes (general population), so duty cycle
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matters enormously. SSB at a normal speech rhythm is a small fraction of your rated output; FM,
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digital modes such as FT8, and a keyed carrier are not.
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## Doing the evaluation
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For nearly every amateur station the arithmetic is a worst-case calculation, not a measurement:
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1. Take the power reaching the antenna (rated output minus feedline loss).
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2. Multiply by the antenna gain in the direction that matters, and by your mode and on-air duty
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cycle.
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3. Compare the resulting power density at the closest distance a person can get to the limit for
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that band.
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The ARRL's RF exposure calculator and the FCC's OET Bulletin 65 Supplement B both do this for you;
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so does the exposure worksheet in most study guides. Print the result, note the date, the band, the
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power, the antenna and the distances, and keep it with your license.
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## Fixing a station that does not pass
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- Move the antenna: distance is the cheapest control there is, and power density falls with the
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square of it.
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- Reduce power, or reduce it only on the band that fails.
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- Change the pattern — point the main lobe away from occupied space, or raise the antenna so its
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lobe clears people.
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- Restrict access while transmitting: a fence, a locked room, or simply not transmitting when
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someone is on the deck under the beam.
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## The rest of station safety
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RF exposure gets the paperwork, but it is not what hurts amateurs. Take at least as seriously:
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- **Line voltage and amplifier supplies.** A tube amplifier holds a lethal charge after it is
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unplugged. Bleeder resistors fail; check with a meter before you reach in.
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- **Falls and power lines.** No antenna is worth touching a utility line — assume any wire you did
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not install is live, and plan the fall path before you raise anything. See
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[towers and masts](/wiki/station/towers-and-masts).
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- **RF burns.** An end-fed wire at head height carries high voltage at its ends. Put those ends
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where nobody can reach them.
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- **Batteries.** Lithium iron phosphate and lead-acid packs both deliver enough current to weld a
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dropped wrench; fuse every battery lead at the battery.
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- **Lightning.** Bond everything to a single ground point and disconnect when a storm approaches;
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see [grounding, bonding and lightning](/wiki/station/grounding-and-lightning).