How does IEC 61000-4-3 differ from a radiated emissions measurement?

Both tests use an anechoic chamber and an antenna, but the EUT plays inverse roles. In radiated emissions (CISPR 32, CISPR 11) the EUT is the source and the antenna receives. In IEC 61000-4-3 a power amplifier drives the antenna to irradiate the EUT, which must keep functioning. The metrology is opposite: emissions measure a level, immunity guarantees a uniform field and observes a functional failure. See the [Radiated emissions](/en/guides/radiated-emissions-emc-test/) guide for the emissions counterpart.

Why 80% AM modulation at 1 kHz?

The 80% amplitude modulation at 1 kHz, defined in clause 6.4 of IEC 61000-4-3, roughly emulates the envelope of a voice transmission or a low-cadence pulsed signal. It raises the crest factor by 5.1 dB versus an unmodulated CW carrier, making the test more severe for circuits with short time constants (radio front-ends, analogue sensors). An unmodulated carrier would not reproduce the real stress imposed by mobile telephony, which is inherently pulsed.

What field level applies to what product?

Standardised levels are 1, 3, 10 and 30 V/m. EN 55035 (residential multimedia) mandates 3 V/m over 80-1000 MHz. EN 55024 (light commercial IT) also calls 3 V/m. EN 61000-6-2 (generic industrial environment) calls 10 V/m. EN 60601-1-2 ed 4.1 (medical) calls 3 V/m over 80-2700 MHz for most devices, 10 V/m for those used near mobile transmitters. ISO 11452-2 (automotive) calls typically 30 to 200 V/m depending on component placement and contractual severity.

What is the uniform field area, and why 1.5 m by 1.5 m?

The uniform field area (UFA) is the vertical surface over which the radiated field must remain stable within -0/+6 dB at no fewer than 12 of the 16 points of a 4x4 grid spaced 0.5 m apart. The regulated size is 1.5 m by 1.5 m (clause 6.2 of IEC 61000-4-3). This area defines the volume in which the EUT can be placed. An EUT larger than 1.5 m requires an enlarged UFA and an extended calibration, or several sequential orientations.

Criteria A, B, C, who defines them?

IEC 61000-4-3 does not define performance criteria. The product standard or the generic immunity standard sets the acceptable criterion. Criterion A requires nominal operation during and after the test, with no degradation. Criterion B allows temporary degradation with automatic return to nominal at stress end. Criterion C allows a temporary loss of function requiring operator intervention (reset, power cycle). Criterion A is typical for safety functions and measurement, B for display and ergonomics, C is rarely accepted for a certified product.

Why the 1.4-6 GHz extension for medical?

EN 60601-1-2 ed 4.0 (2014) and then ed 4.1 (2020) introduced specific tests for proximity to portable wireless transmitters, up to 2700 MHz and then 5800 MHz, per table 9 of the standard. The rationale: mobile phones and Wi-Fi terminals are used a few tens of centimetres from a medical device, producing local fields above 10 V/m in GSM, LTE, UMTS, Wi-Fi 2.4 and 5 GHz bands. The IEC 61000-4-3 extension to 6 GHz (Ed 4.0:2020) standardises the above-1 GHz method to meet this need.

How long does an 80 MHz-1 GHz sweep take?

Duration depends on frequency step and dwell time. The standard requires a step no larger than 1% of the preceding frequency and a dwell time long enough for the EUT to manifest a failure and the observer to detect it, typically 0.5 to 3 seconds. An 80 MHz-1 GHz sweep at 1% yields about 254 points, that is 2 to 13 minutes per polarisation per EUT face. With four faces and two polarisations, a full 80-1000 MHz test runs from 16 minutes to 1.7 hours, excluding calibration time.

What if the EUT fails at a single frequency?

First confirm reproducibility at the same frequency and level, verifying cable arrangement and operating mode. Then sweep around the failure point with a finer step to identify the narrow band responsible. Mitigation depends on frequency: in low VHF, cable coupling dominates (common-mode ferrite, series LC filter on I/O). In UHF and above, direct PCB coupling or enclosure aperture coupling is more common (local decoupling, conductive gasket, local shielding of the sensitive module).

IEC 61000-4-3: radiated RF field immunity

Author Hugues Orgitello Last updated 27 May 2026 ~12 min read

Guide. EMC immunity test method

Radiated RF field immunity is the mirror test of radiated emissions. The same anechoic chamber, the same antenna, but the EUT changes role: it becomes the target of an electromagnetic field driven by a power amplifier, and must keep functioning. IEC 61000-4-3, in its fourth edition published in 2020, defines the field, the modulation, the sweep and the calibration. The 3, 10 and 20 V/m levels are the common values for CE marking, with an automotive extension to 200 V/m and a medical extension up to 6 GHz for proximity to wireless transmitters. This guide describes the method, the A/B/C performance criteria, and the traps that fail an otherwise correctly designed product.

Normative frame and place in the EMC stack

IEC 61000-4-3 is a horizontal standard in the IEC 61000-4 family that groups electrical engineering immunity tests. The first edition appeared in 1995, the current is IEC 61000-4-3 Ed 4.0:2020. It defines the test method. It does not set severity levels or acceptance criteria, which come from product or generic immunity standards.

Standards that call IEC 61000-4-3

The typical structure: a product standard (EN 55035 for multimedia, EN 60601-1-2 for medical, EN 50121 for railway) or a generic standard (EN 61000-6-1 for residential, EN 61000-6-2 for industrial) selects IEC 61000-4-3 as the test method and imposes severity levels per frequency band plus a performance criterion.

Calling standard	Reference field	Band	Criterion
EN 55035 (residential multimedia)	3 V/m	80-1000 MHz	A
EN 55024 (light IT environment)	3 V/m	80-1000 MHz	A
EN 61000-6-1 (generic residential)	3 V/m	80-1000 MHz	A
EN 61000-6-2 (generic industrial)	10 V/m	80-1000 MHz	A
EN 60601-1-2 ed 4.1 (general medical)	3 V/m	80-2700 MHz	A
EN 60601-1-2 ed 4.1 (medical urgent care)	10 V/m	80-2700 MHz	A
ISO 11452-2 (automotive, level IV)	up to 100 V/m	80 MHz-2.7 GHz	OEM

EN 55035 has superseded EN 55020 and EN 55024 for multimedia equipment since 2020. EN 55024 still applies to certain specific IT devices. The table shows the most frequent CE-practice levels, but each product standard may add higher levels for critical functions.

Articulation with ISO 11452 for automotive

The automotive industry developed its own radiated immunity family under ISO 11452. ISO 11452-2 is the absorber-lined chamber variant, conceptually equivalent to IEC 61000-4-3, with severity levels up to 200 V/m reflecting on-board transmitter proximity. ISO 11452-4 (BCI, bulk current injection) and ISO 11452-5 (stripline) are complementary methods used earlier in development. An automotive component typically goes through ISO 11452-4 first, then ISO 11452-2 at higher frequencies.

Radiated immunity is part of a complete EMC campaign: ESD (IEC 61000-4-2), EFT (IEC 61000-4-4), surge (IEC 61000-4-5), conducted RF (IEC 61000-4-6), dips and interruptions (IEC 61000-4-11). See CE tests and RED tests.

IEC 61000-4-3 test method

Frequency band and extensions

The historical reference band is 80 MHz - 1000 MHz (VHF broadcast, digital terrestrial TV, professional VHF/UHF radio, mobile-band roots). Edition 4.0:2020 formally folded in the above-1 GHz extension, previously handled in IEC 61000-4-3:2006/A1:2007. The standardised upper band 1.4-6 GHz covers GSM 1800, UMTS, LTE, 5G FR1, Wi-Fi 2.4 and 5 GHz.

Band	Status in IEC 61000-4-3 Ed 4.0	Radio services covered
80 MHz - 1000 MHz	Main range	VHF, UHF, GSM 900, FM, DVB-T
1.4 GHz - 2.7 GHz	Mandatory extension if called	GSM 1800, UMTS, low LTE, Wi-Fi 2.4
2.7 GHz - 6 GHz	Mandatory extension if called	high LTE, 5G FR1, Wi-Fi 5 and 6

The 1.0-1.4 GHz and 6-18 GHz bands are not covered by default. They appear in specific amendments or in dedicated test protocols (for example in military aeronautics).

Modulation and test signal

The test signal is a carrier amplitude-modulated to 80% by a 1 kHz sinusoidal tone. Clause 6.4 of IEC 61000-4-3: the peak amplitude is 1.8 times the CW carrier, a 5.1 dB crest factor. The level specified by the calling standard is the rms of the unmodulated carrier, and the instantaneous peak under modulation reaches 5.1 dB above that nominal level.

Parameter	Value	Reference
Modulation type	AM	Clause 6.4
Depth	80%	Clause 6.4
Tone frequency	1 kHz sinusoidal	Clause 6.4
Crest factor vs CW	+5.1 dB	Annex D
Reference level	CW carrier rms	Clause 5

This modulation is a coarse approximation of real signals (GSM pulsed at 217 Hz, Wi-Fi bursts, LTE OFDMA). It was chosen for amplifier simplicity and inter-lab reproducibility. The proximity tests in table 9 of EN 60601-1-2 use band-specific modulations closer to the actual signal.

Test site configuration

Absorber-lined chamber (SAR or FAR)

The test runs in a chamber whose walls are lined with ferrite and foam absorbers that suppress reflections. Two configurations are accepted: semi-anechoic with a conductive ground plane (SAR, semi-anechoic room) or fully anechoic (FAR) without ground plane. FAR is preferred above 1 GHz to limit ground-plane reflections. SAR is accepted below 1 GHz but introduces a reflected path that must be calibrated out.

Antennas by band

As with radiated emissions, no single antenna covers 80 MHz to 6 GHz. Typical split:

Band	Transmit antenna
80 - 200 MHz	Biconical or biconilog hybrid
200 MHz - 1 GHz	Log-periodic or biconilog hybrid
1 GHz - 6 GHz	Horn (double-ridge or dual-polarised)

The antenna stands 3 m from the uniform field area in the standard configuration, or 1 m for reduced or proximity tests. The 3 m distance is the normative reference.

Test site diagram

                     ANECHOIC CHAMBER
+----------------------------------------------------+
|                                                    |
|   Ferrite + foam absorbers on all walls            |
|                                                    |
|                              [ ] Field probe       |
|   +-------+                  (calibration / check) |
|   |       |                                        |
|   |   A   |                  +----------+          |
|   | N E   | --- 3 m -------> |          |         |
|   | T R T | -------------->  |   EUT    |         |
|   | E B C | --- E field -->  |  (turn-  |         |
|   | N L   | -------------->  |   table) |         |
|   | N E   |                  +----------+         |
|   |       |                       |               |
|   +-------+                       |               |
|       |                           | I/O cables    |
|       | coax cable                | (peripherals  |
|       |                           |  or simulator)|
+-------|---------------------------|---------------+
        |                           |
   +----+----+                +-----+-----+
   |  Power  |                | Auxiliary  |
   | amp 10W |                | equipment  |
   |  to 500W|                +-----------+
   +---------+
        |
   +----+----+
   |  RF gen |
   | + AM    |
   +---------+

The antenna, power amplifier and RF generator form the transmit chain. The isotropic field probe calibrates the field before the test and may monitor it during the measurement. The EUT I/O cables are arranged in a 30 to 40 cm serpentine per the calling standard. The EUT typically sits on a non-conductive support 0.8 m above the ground plane in SAR, or on a turntable for multi-face tests.

Field-uniformity calibration

The uniform field area (UFA) calibration is the critical step. It is run without the EUT before the test campaign. The isotropic probe is moved over the 16 points of a 4x4 grid spaced 0.5 m apart, in the vertical plane at the test distance. At each point, the field must fall within the -0/+6 dB tolerance around the nominal level, on no fewer than 12 of the 16 points (75%).

UFA parameter	Value	Reference
Standard size	1.5 m x 1.5 m	Clause 6.2
Grid	4 x 4 points	Clause 6.2
Spacing	0.5 m	Clause 6.2
Tolerance	-0 / +6 dB	Clause 6.2
Minimum compliant points	12 of 16 (75%)	Clause 6.2
Calibration frequencies	1% step	Clause 6.2

The amplifier power required to reach the nominal level at each frequency is recorded in a forward power table. That power, not the field measured during the test, is applied to the EUT: once UFA is validated, the field seen by the EUT is known without measuring during the test.

Standardised severity levels

Level	Field	Typical application
1	1 V/m	Protected environment (rare)
2	3 V/m	Residential, light commercial, IT
3	10 V/m	Industrial, medical near wireless
X	30 V/m and above	Heavy industrial, military, automotive

ISO 11452-2 extends the grid up to 200 V/m for automotive, with OEM-contractual levels often higher than standardised values.

Test procedure

Standard sequence

Pre-test without radiation. EUT nominal operation verification, baseline established. Observable criteria are logged (status LEDs, measurement output, active communication).
Place in chamber. EUT positioned at the centre of the uniform field area, representative peripherals connected through filtered cable feedthroughs or with common-mode ferrites.
Power-on in the most representative operating mode. For a multi-mode product, each mode is tested separately.
Frequency sweep with step no larger than 1% of the preceding frequency, 80% AM 1 kHz modulation, dwell time 0.5 to 3 seconds depending on detection speed.
Repeat per polarisation (horizontal, vertical) and per EUT face.
Continuous observation. Frequencies where an event is detected are logged with the event nature (loss of communication, freeze, restart, drift).
Post-test verification against the pre-test baseline.

Dwell time and frequency step

Dwell time must let the EUT manifest a failure AND let the observer detect it. Practical rule: dwell time at least 2x the longest EUT time constant. For equipment with a 500 ms measurement cycle and a 2 Hz display refresh, 1.5 s is a minimum. For a protocol with long timeouts (ModBus 5 s timeout), 3 to 5 s is needed. A dwell time set too short hides long-time-constant failures, the classic trap of an accelerated sweep to meet a deadline.

The 1% step is the normative maximum. A finer step (0.5% or 0.25%) is applied around candidate frequencies: harmonics of internal clocks, IF frequencies of on-board radio receivers, bands of radio services in the destination country (GSM 900, LTE 800, FM 88-108 MHz).

Performance criteria A, B, C

IEC 61000-4-3 does not judge compliance. The verdict comes from the product standard, which sets the expected criterion.

IEC definition

Criterion	Definition	Typical case
A	Nominal operation during and after test	Safety function, precision measurement, critical communication
B	Temporary degradation, automatic return to nominal after	Display, ergonomics, non-critical function
C	Loss of function requiring operator intervention	Rarely accepted for a certified product

Criterion A is the most stringent and the most frequent for essential functions in CE marking. Criterion B is tolerated for visual indicators and ergonomics. Criterion C is almost never accepted for a residential product, and rarely for industrial.

Medical special case

EN 60601-1-2 ed 4.1 goes beyond the plain A/B/C criteria. It defines essential performance for each medical device along with basic safety. The acceptable degradation is assessed against these two notions, and residual clinical risk must be documented per ISO 14971 (risk management for medical devices).

Above-1 GHz specifics

Above 1 GHz, a SAR conductive ground plane causes parasitic reflections. FAR is preferred. UFA calibration is repeated separately for the above-1 GHz band with a finer frequency step. To reach 10 V/m at 3 m at 5 GHz, the required amplifier power often exceeds 50 W cw, that is 250 W peak with 80% AM. The capacity to test above 1 GHz is a major selection criterion for an EMC laboratory.

EN 60601-1-2 ed 4.1 defines a complementary test in table 9: each mobile band (385 MHz TETRA, 450 MHz GMRS, 710-787 MHz LTE 700, 800-960 MHz GSM 900, 1700-1990 MHz GSM 1800, 2400-2570 MHz Wi-Fi 2.4 and LTE 2500, 5100-5800 MHz Wi-Fi 5) is tested at 28 V/m with a service-specific modulation (square 18 Hz for TETRA, pulse 217 Hz for GSM). This test does not replace the IEC 61000-4-3 sweep; it adds to it for medical devices used in care environments.

Common pitfalls in radiated immunity

Six errors recur in failed campaigns.

Dwell time too short. A fast sweep skips long-time-constant failures. Rule: dwell time at least 2x the longest EUT time constant, typically 2 to 5 seconds per point for a measurement device.
Modulation applied to the wrong signal. The error: modulating the peak level instead of the rms. The field actually applied to the EUT is then 5.1 dB below the specified level. Clause 5 of IEC 61000-4-3 is explicit: the specified level is the rms of the unmodulated carrier.
Non-representative cable arrangement. EUT I/O cables act as receive antennas. A tight serpentine has different gain from a stretched cable. A configuration change between calibration and test invalidates the measurement.
EUT in non-representative mode. An idle EUT is not equivalent to the same EUT in transmission or cyclic measurement. Failure frequencies change with mode. Identify all operating modes before entering the chamber, test at least the most critical mode for each essential function.
UFA calibrated for a different level. Calibration is specific to the target field level. A 3 V/m calibration cannot be extrapolated to 10 V/m: amplifier non-linearity and antenna reflections change the spatial field distribution. Each severity level requires its own calibration.
No failure-detection means. The EUT fails, but nothing during the test lets the operator notice. Provide continuous observation of all essential functions with timestamped events before entering the chamber.

Mitigating a radiated immunity failure

When the EUT fails at a given frequency, the approach is the inverse of emissions: reduce field coupling into the sensitive internal point, rather than reducing emission to the outside. Three coupling paths dominate in practice.

Cable coupling. The external cable acts as a receive antenna, and the common-mode voltage propagates to the front-end. Dominant below 300 MHz. Mitigation: common-mode ferrite chosen for peak impedance at the failure frequency, series LC filter on I/O with common-mode capacitor referenced to ground, cable shield with 360-degree termination at both ends.
Enclosure aperture coupling. A slot or ventilation grille behaves as a slot antenna when its dimension approaches lambda/2. Dominant between 300 MHz and a few GHz. Mitigation: mechanical closure below lambda/20 at the peak frequency, conductive gasket on removable covers, metallic mesh on vents.
Direct PCB coupling. Above 1 GHz, long high-impedance traces may receive the field directly. Mitigation: local module shielding, reinforced decoupling, continuous ground plane, guard rings on sensitive analogue signals.

Identifying the path requires discriminating experiments: add a ferrite on a cable (reduces cable coupling), temporarily close an aperture with copper tape (reduces slot coupling), shield a PCB region locally (reduces direct coupling).

See CE tests for the EMC test sequence in CE marking, RED tests for radio products, and Radiated emissions for the emissions counterpart. The glossary covers the acronyms (UFA, SAR, FAR, EUT, dwell time, forward power table).

What to remember

IEC 61000-4-3 Ed 4.0:2020 is the horizontal method for radiated immunity testing, called by product standards (EN 55035, EN 60601-1-2) and generic standards (EN 61000-6-1, EN 61000-6-2). It defines the method, not the levels or the criteria.
The reference band is 80-1000 MHz, with mandatory extensions 1.4-2.7 GHz and 2.7-6 GHz for medical products and any product specifying these bands. Common levels are 3 V/m (residential, multimedia), 10 V/m (industrial, medical proximity).
Modulation is 80% AM at 1 kHz, applied to a carrier whose rms equals the specified level. The instantaneous peak under modulation reaches +5.1 dB above the CW carrier.
The uniform field area (UFA) is 1.5 m x 1.5 m, with -0/+6 dB tolerance at no fewer than 12 of the 16 points of a 4x4 grid spaced 0.5 m. Calibration runs without the EUT, before the test.
A, B, C criteria come from the product standard, not from IEC 61000-4-3. Criterion A is required for safety functions and critical measurement.
ISO 11452-2 is the automotive variant with levels up to 200 V/m, and EN 60601-1-2 adds proximity wireless tests per mobile band on top of the standard IEC 61000-4-3 method.
The main traps are insufficient dwell time, applying modulation to the peak instead of rms, non-representative cable arrangement, and lack of continuous EUT observation.

For practical EU implementation, see CE tests and RED tests. For technical definitions, see the glossary.

Sources & references

IEC 61000-4-3:2020, Testing and measurement techniques, radiated radio-frequency electromagnetic field immunity test , IEC webstore.iec.ch/publication/4191
EN 55035:2017+A11:2020, Electromagnetic compatibility of multimedia equipment, immunity requirements , CENELEC www.cenelec.eu/dyn/www/f?p=104:110:::::FSP_PROJECT,FSP_LANG_ID:60147,25
IEC 60601-1-2:2014+AMD1:2020 CSV, Medical electrical equipment, collateral standard, electromagnetic disturbances , IEC webstore.iec.ch/publication/67347
ISO 11452-2:2019, Road vehicles, component test methods for electrical disturbances from narrowband radiated electromagnetic energy, absorber-lined shielded enclosure , ISO www.iso.org/standard/72840.html
EN 61000-6-2:2019, Electromagnetic compatibility, generic standards, immunity standard for industrial environments , CENELEC www.cenelec.eu/dyn/www/f?p=104:110:::::FSP_PROJECT,FSP_LANG_ID:62395,25