FCC authorization Wireless Charging & RF Exposure

FCC Authorization: Wireless Charging & RF Exposure

Wireless charging devices (Wireless Power Transfer — WPT) have specific FCC authorization requirements, and virtually all wireless products must include an RF exposure evaluation as part of their authorization. This guide explains how both requirements work and when they apply.

Wireless Charging (WPT) — FCC Authorization Overview

Wireless Power Transfer (WPT) devices — commonly used for charging smartphones, wearables, and other consumer electronics — are regulated under FCC Part 15, Subpart H (Wireless Power Transfer Equipment), added by Report and Order FCC 15-99 effective June 2, 2016.

WPT devices operating at 19 kHz to 750 kHz with output power at or below 1 watt may use either SDoC or Certification. WPT devices operating above 750 kHz, or with output power exceeding 1 watt, require FCC Certification through an authorized TCB.

WPT Frequency and Power Classes

Subpart H, §15.709 sets the operating conditions. The fundamental operating frequency band and power level determine both the applicable emission limits and the authorization pathway. Most consumer WPT devices (e.g., Qi chargers at 87–205 kHz) fall under the low-frequency, lower-power provisions but must still address conducted and radiated emissions on harmonics that can reach into the tens of MHz range.

Applicable Standards

FCC WPT testing references ANSI C63.4 for radiated and conducted emissions measurements, plus additional WPT-specific evaluation per §15.709. Coexistence with other wireless devices and immunity from interference is also considered. For WPT devices with intentional wireless communication (e.g., Qi 2.0 with Bluetooth), FCC Part 15C/18 provisions may apply simultaneously.

RF Exposure — Why It's Required for Most Wireless Products

FCC RF exposure requirements apply to virtually all transmitting devices that require FCC authorization. The FCC adopts limits on human exposure to radiofrequency (RF) electromagnetic fields based on guidelines developed by the IEEE and the National Council on Radiation Protection (NCRP), and endorsed by the American National Standards Institute (ANSI).

There are two principal RF exposure evaluation methods:

SAR — Specific Absorption Rate

SAR measures the rate at which energy is absorbed by the human body when exposed to an RF electromagnetic field. It is expressed in watts per kilogram (W/kg). SAR testing is required for devices operated in close proximity to the body — typically any device used within 20 cm of the body. FCC limits: 1.6 W/kg averaged over 1 gram of tissue (general population/uncontrolled environment). Measurement method: IEEE 1528 or IEC 62209.

MPE — Maximum Permissible Exposure

MPE is a calculated (or measured) field strength evaluation used for devices where separation distance from the body is maintained and known. Rather than a tissue absorption measurement, MPE compares the power density of the RF field at the expected separation distance against FCC Table 1 limits (47 CFR §1.1310). Most fixed infrastructure, desktop devices, and products with documented minimum separation distances use MPE evaluation instead of SAR.

When SAR vs. MPE Applies

Mobile Devices (Body-Worn / Handheld)

Smartphones, tablets, wearables, Bluetooth headsets — SAR testing required. Maximum separation distance during normal use is typically 0–25 mm. Full SAR testing per IEEE 1528 required.

Portable Devices (20 cm or more from body)

Devices operated at a defined minimum distance of 20 cm or greater — MPE evaluation is typically sufficient. A separation distance statement must be included in documentation and labeling.

Fixed Infrastructure (Access Points, Routers)

Wi-Fi access points, routers, and similar equipment installed at fixed locations — MPE evaluation at the required minimum separation distance. Often evaluated at 20 cm or greater.

Wireless Charging (WPT)

WPT devices require RF exposure evaluation — typically MPE for devices designed for tabletop use, but SAR may be required if device is placed against the body. Qi chargers typically evaluated at 0 mm (device on top of charger surface).

ⓘ RF exposure evaluation must be included in the technical report filed with (or kept on file for) the FCC authorization — whether SDoC or Certification. A product cannot receive FCC authorization without demonstrating compliance with RF exposure limits.