FCC required tests (Part 15, radio, SAR)

Author Hugues Orgitello Last updated 25 May 2026

FCC · Pillar

FCC tests cover unintentional emissions (Part 15 Subpart B), intentional emitters per the applicable sub-part (15.247, 15.407, etc.), and SAR for worn equipment. Measurement methods are defined by ANSI C63 standards, equivalent but distinct from European CISPR standards.

Unintentional emissions: Part 15 Subpart B

Digital equipment (computers, microcontrollers, digital electronic equipment) is subject to Part 15 Subpart B limits. Measurement method: ANSI C63.4.

Conducted emissions (15.107)

Measurement on mains via LISN, 150 kHz to 30 MHz. Class B (residential) limits:

Frequency	Quasi-peak	Average
150-500 kHz	66 → 56 dB(µV)	56 → 46 dB(µV)
500 kHz - 5 MHz	56 dB(µV)	46 dB(µV)
5 - 30 MHz	60 dB(µV)	50 dB(µV)

Class A (industrial): limits typically 10 dB more permissive.

Radiated emissions (15.109)

Measurement in semi-anechoic chamber, 30 MHz to 1 GHz typically (extended to 6 GHz for products with clocks > 108 MHz).

Class B limits at 3 m:

Frequency	Limit
30 - 88 MHz	100 µV/m (40 dB(µV/m))
88 - 216 MHz	150 µV/m (43.5 dB(µV/m))
216 - 960 MHz	200 µV/m (46 dB(µV/m))
> 960 MHz	500 µV/m (54 dB(µV/m)): peak
> 960 MHz	500 µV/m / √2 (51 dB(µV/m)): average for > 1 GHz

Key difference with EU: FCC limits are in µV/m measured at 3 m, while CISPR/EN limits are in dB(µV/m) at 10 m. The conversion is not direct, values are not equivalent.

Intentional emissions: Part 15 Subpart C

Measurement method: ANSI C63.10.

Part 15.247: Wi-Fi/BLE 2.4 GHz

Main limits:

Parameter	Limit
Conducted power	1 W max (30 dBm)
Antenna gain	6 dBi without power reduction
Spectral density	8 dBm in 3 kHz for FHSS, -1.76 dBm in 100 kHz for DSSS
Out-of-band emissions	-20 dB below in-band level
Spurious emissions	Per Section 15.209

Tests performed in RF anechoic chamber, antenna at 3 m, rotating platform. Multi-frequency tests (extreme and centre channels) and multi-modulation.

Part 15.407: Wi-Fi 5/6 GHz U-NII

Limits per U-NII sub-band (see FCC Parts for full table). For U-NII-2 (5.25-5.35 and 5.47-5.725 GHz), DFS mandatory:

Radar signal detection with sensitivity < -64 dBm/MHz
Channel switching in < 10 s after detection
Continuous surveillance in active mode

For U-NII-5/-7 Standard Power (5.925-6.425 and 6.525-6.875 GHz), AFC mandatory since 2023, central coordination system with geo-located database.

Cellular limits (Parts 22, 24, 27)

Tests conform to 3GPP suites:

TS 36.521 for LTE (Series 36)
TS 38.521 for 5G NR (Series 38)
TS 51.010 for GSM

Performed in anechoic chamber with simulated base station (Anritsu, Keysight, Rohde & Schwarz). Tests cover:

Transmit power per band and configuration
Emission spectrum (mask)
Frequency error
EVM (Error Vector Magnitude) in modulation
In-band and out-of-band spurious
ACLR (Adjacent Channel Leakage Ratio)

SAR: Human RF exposure

For equipment worn within 20 cm of the body, SAR is mandatory. FCC method documented by:

KDB 248227, general SAR method
KDB 941225: 5 GHz SAR method
KDB 447498: SAR for modules
KDB 178919, handheld devices

US SAR limits

Whole-body: 0.08 W/kg averaged over the whole body
Localised partial body: 1.6 W/kg averaged over 1 g of tissue (vs 10 g in EU, stricter)
Hands, wrists, feet, ankles: 4 W/kg averaged over 10 g

The FCC uses 1 g averaging, EU uses 10 g. A US product at SAR limit may exceed the EU limit after conversion. Always check both at design time.

Measurement method

Preparation: equipment charged, configured at maximum power.
Phantom: anatomical model with liquid simulating tissues at the assessed frequency.
Robotic dosimetric probe scanning the phantom.
SAR calculation averaged over 1 g of tissue.
Configurations tested: multiple body positions (head, hand, pocket, hip).

Typical cost per configuration: $3,000 to $8,000. For a multi-band 4G/5G + Wi-Fi + BLE phone, count 8 to 15 configurations.

MPE: Maximum Permissible Exposure

For fixed or non-worn equipment, FCC authorises alternative assessment based on MPE:

Range	Power density limit
300 kHz - 3 MHz	100 mW/cm²
3 - 30 MHz	900/f² mW/cm²
30 - 300 MHz	1 mW/cm²
300 - 1500 MHz	f/300 mW/cm²
1500 - 100000 MHz	5 mW/cm²

For a Wi-Fi access point at 1 W conducted, MPE assessment at 20 cm typically gives 0.5-1 mW/cm², below the 5 mW/cm² limit. The assessment is documentary (theoretical calculation) rather than physical test.

Test bench and labs

Equipment needed for FCC tests

Minimum bench for pre-tests:

Equipment	Use
Spectrum analyser 10 kHz – 18 GHz	Conducted + radiated + radio emissions
LISN 50 Ω / 50 µH	Conducted emissions
Biconical + log-periodic antenna	Radiated measurement
ESD gun ± 30 kV	Immunity (rarely mandatory in FCC but good practice)
Semi-anechoic chamber or shielded chamber	Radiated measurement

FCC pre-test bench cost: $50,000 to $150,000 typical.

FCC-accredited labs

Labs must have FCC accreditation (or A2LA, ILAC equivalence) for their reports to be accepted by TCBs. Main US labs:

TÜV Rheinland of North America
Bureau Veritas Consumer Products
UL Verification Services
Element
SGS
Eurofins MET Labs
CETECOM
EMC Technologies

Lead times: 4 to 10 weeks typically, faster for standard Wi-Fi/BLE products.

Typical test plan

For an IoT Wi-Fi/BLE + LTE Cat-M product:

Week 1-2 : Internal pre-tests (conducted emissions, ESD)
Week 3   : Design fixes
Week 4   : Shipment to lab
Week 5-6 : Part 15 Subpart B tests (digital emissions)
Week 7-8 : Part 15.247 tests (Wi-Fi/BLE 2.4 GHz)
Week 9   : Part 15.407 tests if 5 GHz Wi-Fi applicable
Week 10-12: LTE Cat-M tests (3GPP)
Week 13  : SAR (if worn equipment)
Week 14  : Final report

Total lab: 8 to 14 weeks depending on complexity.

Indicative costs

Campaign	Range
Part 15 Subpart B (digital equipment)	$4,000 – $12,000
Part 15.247 (Wi-Fi/BLE 2.4 GHz)	$5,000 – $15,000
Part 15.407 (Wi-Fi 5/6 GHz)	$7,000 – $18,000
LTE Cat-M / NB-IoT	$15,000 – $35,000
Complete LTE (multi-band)	$25,000 – $60,000
5G NR sub-6 GHz	$40,000 – $100,000
5G NR mmWave	$80,000 – $200,000
SAR (per configuration)	$3,000 – $8,000
MPE (documentary calculation)	$1,000 – $3,000
Retest after modification	$1,000 – $5,000

Add $3,000 to $8,000 TCB fees per submission.

Comparison with European tests (RED)

Aspect	FCC	RED
EMC method	ANSI C63.4	CISPR 32 / EN 55032
Radio method	ANSI C63.10	EN 300 328, EN 301 893
Wi-Fi 2.4 GHz limits	1 W conducted	100 mW EIRP
SAR averaging	1 g	10 g
Channel access mechanism	Not imposed (except 5 GHz DFS)	AFH/LBT/APC required in 2.4 GHz
Cybersecurity	No obligation	RED 3.3 since August 2025

For a product targeting both markets, plan distinct configurations or regionally-adaptable firmware.