# FM / TV broadcast transmitter

> Broadcast sites radiate tens to hundreds of kilowatts ERP — thousands of times a cell sector — but from tall masts in the 30–300 MHz band where the FCC's public limit is at its most restrictive.

- Canonical URL: https://emfbase.com/emitters/fm-broadcast-tower
- Collection: Sources & emitters
- Record id: `emitters:fm-broadcast-tower`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/emitters/fm-broadcast-tower
- Also known as: radio mast, broadcast antenna, TV transmitter

## Key values

- **Category:** radiofrequency
- **Emission bands:** FM broadcast (88–108 MHz); VHF/UHF television
- **Environments:** outdoor
- **Transmit power:** 100,000 W EIRP — Regulatory value — legally enforceable — 100 kW ERP is a mid-size FM allocation; licensed powers range from a few hundred watts to over 1 MW ERP for some TV facilities. [fcc-oet65]
- **Duty cycle:** Continuous, constant-envelope transmission — unlike cellular, there is no traffic-dependent variation.

## Field strength by distance

- **100 m:** 796,000 µW/m² — Computed estimate — S = EIRP / (4πd²) with EIRP = 100000 W, d = 100 m — Main-beam free-space value; broadcast antennas concentrate energy toward the horizon, not the tower base. [fcc-oet65]
- **500 m:** 31,800 µW/m² — Computed estimate — S = EIRP / (4πd²) with EIRP = 100000 W, d = 500 m — Main-beam free-space value. [fcc-oet65]
- **2000 m:** 1,990 µW/m² — Computed estimate — S = EIRP / (4πd²) with EIRP = 100000 W, d = 2000 m — Main-beam free-space value. [fcc-oet65]

## Mitigations, most effective first

- **Check the FCC ASR and licence records for ERP, height and antenna pattern before estimating exposure.** — Broadcast exposure is dominated by height and pattern, which vary enormously between sites.
- **Measure with a meter that covers 88–700 MHz; many consumer RF meters start at 200 MHz or higher and will read near zero next to an FM mast.** — Prevents a false negative caused by the meter's lower frequency limit.

## Measure with

- Broadband RF power-density meter
- RF spectrum analyser

## Related records

- [FCC general population MPE, 30–300 MHz](https://emfbase.com/limits/fcc-public-limit-30-300-mhz): The most restrictive RF band in the FCC table — 0.2 mW/cm², equivalently 27.5 V/m — covering FM broadcast, TV and land-mobile services.

## Sources

- `fcc-oet65` Federal Communications Commission, Office of Engineering and Technology (1997). *OET Bulletin 65: Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields*. https://www.fcc.gov/general/oet-bulletins-line — government, link checked 2026-08-12
- `fcc-asr` Federal Communications Commission. *Antenna Structure Registration (ASR) public access database downloads*. https://www.fcc.gov/wireless/data/public-access-files-database-downloads — government, link checked 2026-08-12
- `fcc-1310` U.S. Government Publishing Office (eCFR). *47 CFR § 1.1310 — Radiofrequency radiation exposure limits*. https://www.ecfr.gov/current/title-47/section-1.1310 — regulation, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.