Most RF emissions guides describe a process without naming a single limit. This one names them. You will find the FCC field-strength ceilings your product must clear, the methods an accredited lab uses to measure against them, plus the EU requirement that became enforceable in August 2025.
- Which standard governs your product in each market you enter
- The exact FCC limits your device must meet, in µV/m and dBµV
- How labs measure conducted emissions differently from radiated emissions
- The design choices that keep your product under those limits
- The new EU cybersecurity requirement that gates your CE marking
Which Standard Applies to Your Product
Your product category selects the standard. Your industry does not.
| Market | Standard | Applies to |
| U.S. | FCC Part 15, Subpart B | Unintentional radiators (digital devices) |
| U.S. | FCC Part 15, Subparts C and E | Intentional radiators such as Wi-Fi and Bluetooth |
| EU | EN 55032 (CISPR 32) | Multimedia equipment, 9 kHz to 400 GHz |
| EU | EN 301 489 series | EMC for radio equipment under the RED |
CISPR 32:2015 Edition 2.0 sets emission requirements for multimedia equipment rated at or below 600 V. EN 55032 adopts that text in Europe. ETSI EN 301 489-1 V2.2.3 carries the current EMC framework for radio equipment. If your compliance plan still cites CISPR 22, ask your lab to confirm which standard your test report will reference.
The Limits Your Device Must Clear
FCC rules sort digital devices into two classes by where you market them. Class B covers products you sell into homes. Class A covers commercial and industrial settings. Class B limits run tighter, because consumers place products beside televisions and radios.
Radiated emission limits (47 CFR § 15.109)
| Frequency (MHz) | Class A at 10 m (µV/m) | Class B at 3 m (µV/m) |
| 30–88 | 90 | 100 |
| 88–216 | 150 | 150 |
| 216–960 | 210 | 200 |
| Above 960 | 300 | 500 |
Conducted emission limits on the AC power line (47 CFR § 15.107)
| Frequency (MHz) | Class A QP / Average (dBµV) | Class B QP / Average (dBµV) |
| 0.15–0.5 | 79 / 66 | 66–56 / 56–46* |
| 0.5–5 | 73 / 60 | 56 / 46 |
| 5–30 | 73 / 60 | 60 / 50 |
*Class B limits decrease logarithmically with frequency across this band. Where a frequency lands on a band edge, the tighter limit governs.
How Labs Run the Measurement
Two setups cover the full range.
| Test | Range | Setup | Detector |
| Conducted | 150 kHz to 30 MHz | 50 µH/50 Ω LISN on the AC line | Quasi-peak plus average |
| Radiated, low band | 30 MHz to 1 GHz | Semi-anechoic chamber or open-area test site | Quasi-peak |
| Radiated, high band | Above 1 GHz | Chamber at 1 MHz resolution bandwidth | Average, with peak capped 20 dB higher |
FCC rules point to ANSI C63.4-2014 for measurement procedures. Your lab may measure at a distance other than the one printed in the limit table, then extrapolate at 20 dB per decade above 30 MHz. That flexibility matters when ambient noise swamps a 10 m reading.
Two visits to the lab serve different purposes. A pre-compliance scan trades formality for speed. Engineers run it on a bench or in a shorter chamber booking, chase the tallest peaks, then iterate the same afternoon. A compliance test follows the full accredited procedure under a controlled setup, which produces the report a certification body will accept. Treat the first as diagnosis. Treat the second as proof.
Schedule the diagnosis before you freeze the design. A problem caught at layout costs you a board revision. The same problem caught at certification costs you a launch window.
Design Choices That Keep You Under the Limit
Most emissions failures trace back to decisions engineers made months before anyone booked a chamber. Treat every conductor leaving the enclosure as a potential antenna, because cables radiate far more efficiently than the circuit driving them.
| Design Area | Practical Move | What It Buys You |
| PCB layout | Route high-speed traces over an unbroken ground plane | Shortens the return current loop that radiates |
| PCB layout | Separate the high-frequency section from I/O connectors | Stops switching noise coupling onto exit cables |
| Shielding | Enclose the noisiest subassembly in a grounded can | Contains fields before they reach enclosure seams |
| Grounding | Bond shields to chassis at several points | Keeps the shield itself from resonating |
| Filtering | Fit a common-mode choke at the power entry | Targets the 150 kHz to 30 MHz conducted band |
| Filtering | Add ferrites to cables leaving the product | Cuts cable-driven radiation above 30 MHz |
None of these moves costs much at the schematic stage. Each becomes expensive once you have tooling, certified firmware, plus inventory sitting in a warehouse.
The EU Requirement That Now Gates CE Marking
Commission Delegated Regulation (EU) 2022/30 activated three cybersecurity requirements under Article 3(3) of the Radio Equipment Directive. Regulation (EU) 2023/2444 pushed the application date to 1 August 2025. Internet-connected radio equipment on the EU market must satisfy all three today.
| Article | Requirement | Status |
| 3(3)(d) | Protects the network from harm | In force since 1 August 2025 |
| 3(3)(e) | Safeguards personal data and user privacy | In force since 1 August 2025 |
| 3(3)(f) | Protects against fraud | In force since 1 August 2025 |
Clean emissions results no longer clear your product for Europe on their own. MiCOM Labs holds A2LA accreditation for RED cybersecurity assessments and operates as an EU Conformity Assessment Body, so a single lab can close both scopes without a second vendor handoff.
Bring Your Lab In Before Layout Freezes
MiCOM Labs runs ISO/IEC 17025 accredited testing from Pleasanton, California, with measurement capability to 220 GHz. The lab also holds ISO/IEC 17065 TCB accreditation, which means it can certify the product it tests.
When comparing labs for ongoing RF emissions testing, it’s worth asking who will actually be running your tests next year. MiCOM Labs has remained family-owned since 2001, so clients work with a consistent engineering team and get consistent results, without the turnover that often follows a lab acquisition.
Call (925) 462-0304 or send your product details through the contact form to scope your test plan.