47 CFR § 18.309 - Frequency range of measurements.

---
identifier: "/us/cfr/t47/s18.309"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "47 CFR § 18.309 - Frequency range of measurements."
title_number: 47
title_name: "Telecommunication"
section_number: "18.309"
section_name: "Frequency range of measurements."
chapter_name: "FEDERAL COMMUNICATIONS COMMISSION"
subchapter_number: "A"
subchapter_name: "GENERAL"
part_number: "18"
part_name: "INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "47 U.S.C. 154, 301, 302, 303, 304, 307."
regulatory_source: "50 FR 36067, Sept. 5, 1985, unless otherwise noted."
cfr_part: "18"
---


# 18.309 Frequency range of measurements.

(a) For field strength measurements:

|  |  |  |
| --- | --- | --- |
| Below 1.705 | Lowest frequency generated in the device, but not lower than 9 kHz | 30 MHz. |
| 1.705 to 30 | Lowest frequency generated in the device, but not lower than 9 kHz | 400 MHz. |
| 30 to 500 | Lowest frequency generated in the device or 25 MHz, whichever is lower | Tenth harmonic or 1,000 MHz, whichever is higher. |
| 500 to 1,000 | Lowest frequency generated in the device or 100 MHz, whichever is lower | Tenth harmonic. |
| Above 1,000 | ......do | Tenth harmonic or highest detectable emission. |

(b) For conducted powerline measurements, the frequency range over which the limits are specified will be scanned.

[50 FR 36070, Sept. 5, 1985, as amended at 51 FR 17971, May 16, 1986]