ISO 11452-11:2010

Road vehicles - Component test methods for electrical disturbances from narrowband radiated electromagnetic energy - Part 11: Reverberation chamber

ISO 11452-11:2010 specifies a reverberation chamber method for testing the immunity (off-vehicle radiation source) of electronic components for passenger cars and commercial vehicles, regardless of the propulsion system (i.e. spark-ignition engine, diesel engine, electric motor). The device under test (DUT), together with the wiring harness (prototype or standard test harness), is subjected to an electromagnetic disturbance generated inside the reverberation chamber, with peripheral devices either inside or outside the chamber. It is applicable to disturbances from continuous narrowband electromagnetic fields. The test is performed using the tuned mode method.

Véhicules routiers — Méthodes d'essai d'un équipement soumis à des perturbations électriques par rayonnement d'énergie électromagnétique en bande étroite — Partie 11: Chambre réverbérante

General Information

• Status: Published
• Publication Date: 02-Sep-2010
• ICS: 33.100.20 - Immunity
• ICS: 43.040.10 - Electrical and electronic equipment
• Technical Committee: ISO/TC 22/SC 32 - Electrical and electronic components and general system aspects
• Drafting Committee: ISO/TC 22/SC 32/WG 3 - Electromagnetic compatibility
• Current Stage: 9092 - International Standard to be revised
• Start Date: 14-May-2025
• Completion Date: 13-Dec-2025

Overview - ISO 11452-11:2010 (Reverberation chamber)

ISO 11452-11:2010 specifies a reverberation chamber method to test the immunity of electronic components used in passenger cars and commercial vehicles to narrowband radiated electromagnetic energy from off‑vehicle radiation sources. The standard covers tests performed with the tuned mode (reverberation) method, applicable from the chamber’s lowest usable frequency (LUF) up to 18 GHz. The device under test (DUT) is evaluated together with its wiring harness and any required support equipment inside the chamber, while peripheral equipment can be inside or outside the chamber.

Key technical topics and requirements

• Test principle: Tuned‑mode reverberation chamber (mechanical tuners stir the field to produce a statistically uniform field).
• Frequency range: From the chamber LUF (determined during chamber characterization) to 18 GHz.
• Chamber characterization: Annex B defines procedures to determine LUF and field uniformity; chamber loading factors (CLF, MLF) and chamber characterization factor (CCF) are used to quantify loading effects.
• Test set‑up constraints:
  • Working volume must be large enough to house DUT, harness, support equipment and receiving antenna.
  • At LUF, working volume shall be at least λ/4 from chamber surfaces and antennas.
  • DUT, test bench and support equipment should occupy no more than 8% of total chamber volume.
  • Test bench minimum height: λ/4 at the lowest frequency.
• Required instrumentation: isotropic E‑field probe, RF signal generator, transmitting/receiving antennas (≥75% efficiency recommended), power amplifiers, spectrum analyser, directional coupler, power meter and computer control/software for characterization and test automation.
• DUT stimulation and monitoring: Use non‑intrusive actuators (plastic, pneumatic) and fibre‑optic or high‑resistance connections to avoid altering electromagnetic behaviour.
• Test method & reporting: Test plans, procedures and performance status classifications are specified (see Clause 8 and Annex A).

Practical applications and who uses this standard

• Use cases:
  • R&D and design verification for ECUs, sensors, modules and other in‑vehicle electronics.
  • Pre‑compliance and production quality control to verify immunity to continuous narrowband sources (e.g., radio transmitters).
  • Comparative evaluation of harness designs and shielding or grounding strategies.
• Typical users:
  • Automotive OEMs and tier‑1/2 suppliers.
  • EMC laboratories and test houses offering reverberation chamber services.
  • Component developers and quality engineers focused on electromagnetic compatibility (EMC).

Related standards and references

• Normative reference: ISO 11452-1 (general principles and terminology).
• Other parts of ISO 11452 (listed in the standard) cover alternate component test methods: absorber-lined shielded enclosure, TEM cell, harness excitation, stripline, direct RF injection, magnetic-field immunity, portable transmitters, conducted disturbances, etc. These are useful for complementary EMC testing outside reverberation chambers.

Keywords: ISO 11452-11, reverberation chamber, vehicle component EMC testing, narrowband radiated electromagnetic energy, DUT immunity, tuned mode, lowest usable frequency (LUF), chamber characterization.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11452-11
First edition
2010-09-01
Road vehicles — Component test
methods for electrical disturbances from
narrowband radiated electromagnetic
energy —
Part 11:
Reverberation chamber
Véhicules routiers — Méthodes d'essai d'un équipement soumis à des
perturbations électriques par rayonnement d'énergie électromagnétique
en bande étroite —
Partie 11: Chambre réverbérante

Reference number
©
ISO 2010
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©  ISO 2010
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ii © ISO 2010 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Test conditions .3
5 Test location .3
5.1 General .3
5.2 Reverberation chamber .3
6 Test apparatus and instrumentation .3
6.1 Isotropic E-field probe .3
6.2 RF signal generator.3
6.3 Transmitting and receiving antennas.4
6.4 Power amplifiers.4
6.5 Spectrum analyser .4
6.6 Directional coupler .4
6.7 Power meter .4
6.8 Computer control .4
6.9 Stimulation and monitoring of the DUT .4
7 Test set-up .5
7.1 General .5
7.2 Ground plane and DUT grounding .5
7.3 Power supply and AN.5
7.4 Location of DUT and wiring harness.6
7.5 Location of load simulator.6
7.6 Location of transmitting antenna .6
7.7 Location of receiving antenna .6
8 Test method .8
8.1 Test plan.8
8.2 Test procedure.8
8.3 Test report.9
Annex A (informative) Function performance status classifications (FPSC) .11
Annex B (normative) Mode tuning chamber characterization .12
Annex C (normative) Determination of chamber loading effects .18
Annex D (normative) Artificial network .21
Bibliography.23

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11452-11 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
ISO 11452 consists of the following parts, under the general title Road vehicles — Component test methods
for electrical disturbances from narrowband radiated electromagnetic energy:
⎯ Part 1: General principles and terminology
⎯ Part 2: Absorber-lined shielded enclosure
⎯ Part 3: Transverse electromagnetic mode (TEM) cell
⎯ Part 4: Harness excitation methods
⎯ Part 5: Stripline
⎯ Part 7: Direct radio frequency (RF) power injection
⎯ Part 8: Immunity to magnetic fields
⎯ Part 9: Portable transmitters
⎯ Part 10: Immunity to conducted disturbances in the extended audio frequency range
⎯ Part 11: Reverberation chamber

iv © ISO 2010 – All rights reserved

Introduction
Immunity measurements of complete road vehicles can generally only be carried out by the vehicle
manufacturer, owing to, for example, high costs of absorber-lined shielded enclosures, the desire to preserve
the secrecy of prototypes or a large number of different vehicle models.
For research, development and quality control, a laboratory measuring method can be used by both vehicle
manufacturers and equipment suppliers to test electronic components.
This test method is based on parts of IEC 61000-4-21 and RTCA/DO-160E.

INTERNATIONAL STANDARD ISO 11452-11:2010(E)

Road vehicles — Component test methods for electrical
disturbances from narrowband radiated electromagnetic
energy —
Part 11:
Reverberation chamber
1 Scope
This part of ISO 11452 specifies a reverberation chamber method for testing the immunity (off-vehicle
radiation source) of electronic components for passenger cars and commercial vehicles, regardless of the
propulsion system (i.e. spark-ignition engine, diesel engine, electric motor). The device under test (DUT),
together with the wiring harness (prototype or standard test harness), is subjected to an electromagnetic
disturbance generated inside the reverberation chamber, with peripheral devices either inside or outside the
chamber. It is applicable to disturbances from continuous narrowband electromagnetic fields.
The test is performed using the tuned mode method.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 11452-1, Road vehicles — Component test methods for electrical disturbances from narrowband radiated
electromagnetic energy — Part 1: General principles and terminology
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11452-1 and the following apply.
3.1
antenna characterization factor
ACF
ratio of the average received power to forward power obtained in the antenna characterization
NOTE See Clause B.5.
3.2
chamber characterization factor
CCF
normalized average received power over one tuner rotation with the DUT and supporting equipment present
NOTE See Clause C.3.
3.3
chamber loading factor
CLF
ratio of the antenna characterization factor to the chamber characterization factor
NOTE 1 See Clause C.4.
NOTE 2 It is a measure for the additional loading of the chamber due to the test setup including, for example, the DUT
and the support equipment.
3.4
lowest usable frequency
LUF
lowest frequency for which the field uniformity requirements are met
NOTE The LUF is determined during the characterization of the chamber in accordance with Annex B.
3.5
maximum chamber loading factor
MLF
maximum chamber loading factor for which the field uniformity has been demonstrated using the procedure
defined in Clause B.7
3.6
reverberation chamber
high Q shielded room (cavity) whose boundary conditions are changed via one or several stepped rotating
tuners
NOTE This results in a statistically uniform electromagnetic field.
3.7
support equipment
equipment associated with performing an EMC test on a DUT including (but not all inclusive) load simulator,
wiring harnesses, power supply (or batteries), DUT monitoring equipment including fibre optic interface
modules and TV camera
3.8
test bench
polystyrene block(s) with a minimum height above the ground floor of λ/4 at the lowest frequency
NOTE Typically a 1 m high support is used.
3.9
tuner
large metallic reflector capable of changing the electromagnetic boundary conditions in a reverberation
chamber as it rotates or moves
NOTE As the tuner moves, the nulls and maximums in the field change location, ensuring the device under test
(DUT) is exposed to a statistically uniform field.
3.10
working volume
volume within the reverberation chamber that contains the test bench, the DUT, the harness, the support
equipment that is located on the test bench, and the receiving antenna
2 © ISO 2010 – All rights reserved

4 Test conditions
The applicable frequency range of the test method is from LUF (see Clause B.6) to 18 GHz.
The user of this part of ISO 11452 shall specify the test severity level or levels over the frequency bands.
Typical test levels are suggested in Annex A.
Standard test conditions are given in ISO 11452-1 for the following:
⎯ test temperature;
⎯ supply voltage;
⎯ modulation;
⎯ dwell time;
⎯ test signal quality.
5 Test location
5.1 General
The test shall be performed in a reverberation chamber.
5.2 Reverberation chamber
The chamber shall be large enough to test the DUT including the test bench, the support equipment, and the
receiving antenna within the chamber's working volume.
NOTE 1 The chamber size will influence the lowest useable frequency (LUF).
This working volume typically has a cuboid shape, but this is not a requirement.
The reverberation chamber shall contain at least one mechanical tuner to stir the electromagnetic fields inside
the chamber. The mechanical tuner(s) should be as large as possible with respect to overall chamber size and
working volume considerations. In addition each tuner should be shaped such that a non-repetitive field
pattern is obtained over one revolution of the tuner.
NOTE 2 The number, size and shape of the tuners will influence the lowest useable frequency (LUF).
After initial construction, the reverberation chamber shall be characterized in accordance with Annex B, and
fulfil the field uniformity requirements of Table B.2. The LUF of the reverberation chamber is determined
during this initial characterization. Following any major modifications, a new chamber characterization shall be
carried out again. Changes to the tuners shall be considered a major modification.
6 Test apparatus and instrumentation
6.1 Isotropic E-field probe
The field probe shall be capable of measuring electric field strength in three orthogonal axes.
6.2 RF signal generator
The RF signal generator shall be capable of covering the specified frequency bands and modulations.
6.3 Transmitting and receiving antennas
Linearly polarized antennas capable of satisfying the frequency requirements shall be used for transmitting
and receiving, respectively. The antenna efficiency should be at least 75 % (log periodic and horn antennas
typically fulfil this requirement). The use of multiple antennas to cover the complete frequency range of the
reverberation chamber is allowed.
6.4 Power amplifiers
The power amplifiers are used to amplify the RF signal and provide the necessary power to the transmitting
antenna to produce the specified field strengths.
6.5 Spectrum analyser
The spectrum analyser shall be capable of covering the specified frequency bands. The spectrum analyser is
used in conjunction with the receiving antenna during the chamber characterization with and without the DUT.
6.6 Directional coupler
The directional coupler shall be capable of covering the specified frequency bands. It shall be capable of
handling the RF output of the power amplifier without damage. The directional coupler is used in conjunction
with the power meter to measure the forward power delivered to the transmitting antenna.
6.7 Power meter
The power meter shall be capable of covering the specified frequency bands. The power meter is used in
conjunction with the directional coupler to measure the forward power delivered to the transmitting antenna.
6.8 Computer control
Specialized software used in conjunction with a computer and the RF test equipment should be utilized to
characterize the chamber performance in accordance with Annex B, prior to any DUT testing. The software
should store the characterization information for use during testing. The computer and software will then be
used to control the RF test equipment and tuner during DUT testing. The software shall be capable of
performing the tests as described in Clause 8.
6.9 Stimulation and monitoring of the DUT
The DUT shall be operated as required in the test plan by actuators which have a minimum effect on the
electromagnetic characteristics, e.g. plastic blocks on the push-buttons, pneumatic actuators with plastic tubes.
Connections to equipment monitoring electromagnetic interference reactions of the DUT may be
accomplished by using fibre-optics, or high resistance leads. Other type of leads may be used but require
extreme care to minimize interactions. The orientation, length and location of such leads shall be carefully
documented to ensure repeatability of test results.
Any electrical connection of monitoring equipment to the DUT may cause malfunctions of the DUT. Extreme
care shall be taken to avoid such an effect.
4 © ISO 2010 – All rights reserved

7 Test set-up
7.1 General
A general layout of the reverberation chamber is shown in Figure 1.
At the LUF, the working volume shall be at least λ/4 from any chamber surface, field generating antenna or
tuner assembly. The DUT and wiring harness shall be located within the chamber working volume.
The volume of the DUT, test bench and support equipment should not occupy more than 8 % of the total
chamber volume.
All unnecessary RF absorbing material shall be removed from the room (e.g. wooden tables, carpeting, extra
equipment, etc.).
The equipment placed in the chamber (DUT, wiring harness, support equipment, ground plane) may load the
chamber beyond that of the maximum loading verification. Prior to collecting data a check shall be performed
to determine if the DUT, or its support equipment, or both the DUT and its support equipment, have adversely
loaded the chamber. This check shall be performed as outlined in Annex C.
7.2 Ground plane and DUT grounding
If the DUT outer case is not grounded to the vehicle metal structure, the DUT and harness shall be placed
either
⎯ directly on the test bench (without ground plane), or
⎯ insulated from a ground plane placed on the test bench.
If the outer case of the DUT is intended to be grounded to the vehicle metal structure, the DUT case should be
grounded to a ground plane during testing (either to the ground floor or through a ground plane placed on the
test bench). Grounding of the DUT case shall simulate the actual vehicle configuration.
The test bench ground plane (if used) shall be constructed from either copper, brass or galvanized steel. The
minimum size of the ground plane depends upon the size of the system under test and shall allow for
complete harness and system component placement. The ground plane (excluding the grounding connection)
shall be placed within the chamber working volume and at least λ/4 from any wall and tuner at the lowest
frequency of use. The ground plane shall be bonded to the chamber with bonding straps such that the d.c.
resistance shall not exceed 2,5 mΩ. In addition, the bond straps shall be placed at a distance no greater than
0,3 m apart edge to edge.
NOTE Using the ground floor as ground plane is an alternative method that is currently being studied.
7.3 Power supply and AN
When a d.c. power supply is needed to maintain battery voltage, the d.c. power supply shall be located
outside the test chamber. All power lines entering the chamber shall be filtered. The d.c. power leads used for
battery maintenance within the chamber may be shielded from the chamber filter to the battery connection
point. The d.c. power leads within the chamber should be routed along the wall and chamber floor in order to
minimize field coupling to these leads.
If no ground plane is used, then artificial networks shall not be used. The power feeds to the DUT shall be
connected directly to the battery terminals.
If a ground plane is used, then each power supply lead shall be connected to the power supply through an AN.
Power shall be applied to the DUT via a 5 µH/50 Ω AN (see Annex D for the schematic). The number of ANs
required depends upon the intended DUT installation in the vehicle.
⎯ For a remotely grounded DUT (vehicle power return line longer than 200 mm), two ANs are required: one
for the positive supply line and another for the power return line. The power supply negative terminal shall
be connected to the ground plane on the source (input) side of the return line AN.
⎯ For a locally grounded DUT (vehicle power return line 200 mm or shorter), only one AN is required for the
positive supply line. The DUT power return line shall be no longer than 200 mm and connected directly to
the ground plane. The power supply negative terminal shall be connected to the ground plane near the
AN case ground.
The ANs shall be mounted directly on the ground plane. The case or cases of the AN(s) shall be bonded to
the ground plane.
The measuring port of each AN shall be terminated with a 50 Ω load.
7.4 Location of DUT and wiring harness
+300
A 17 00 mm wiring harness shall be used, unless otherwise specified in the test plan. The wiring
()
harness should be representative of the actual installation (shielded, unshielded, twisted pair, etc.). The length
of the wiring harness shall be documented in the test report.
The wiring harness shall be placed in a “U-shaped” configuration to allow a straight harness length of
+45
(1 500 ± 75) mm between the DUT and the load simulator. Harness bends shall be 90 °.
()
If a ground plane is used, the DUT and harness shall be elevated (50 ± 5) mm above the ground plane with a
non-conductive, low permittivity (dielectric-constant) material (relative permittivity, ε u 1,4).
r
7.5 Location of load simulator
Preferably, the load simulator shall be placed directly on the ground plane (if used). If the load simulator has a
metallic case, this case shall be bonded to the ground plane.
Alternatively, the load simulator may be located adjacent to the ground plane (with the case of the load
simulator bonded to the ground plane) or outside of the test chamber, provided the test harness from the DUT
passes through an RF boundary bonded to the ground plane.
When the load simulator is located on the ground plane, the d.c. power supply lines of the load simulator shall
be connected through the AN(s).
7.6 Location of transmitting antenna
The location of the transmitting (Tx) antenna shall be the same for both characterization and testing. The
transmitting antenna shall not directly illuminate the working volume. The transmitting antenna should be
directed into a corner of the chamber if possible (see Figure 1 for location of transmitting antenna). Directing
the antenna into the tuner is also acceptable. The transmitting antenna should be supported by a non-
conductive stand (e.g. non-conductive tripod or polystyrene fixture) and should be placed at a distance not
less than λ/4 (at lowest frequency) from the chamber walls and corners.
NOTE An upward tilt of the antenna is advisable to avoid direct incident wave illumination of the chamber wall
resulting in a potentially high VSWR situation.
7.7 Location of receiving antenna
The receiving (Rx) antenna may be placed at an arbitrary position within the chamber working volume and
should be placed on a polystyrene support. The receiving antenna shall avoid pointing at the transmitting
antenna and centre of the working volume.
6 © ISO 2010 – All rights reserved

Dimensions in millimetres
Key
1 tuner 11 spectrum analyser
2 DUT 12 computer system with software
3 chamber working volume 13 computer interface
4 Tx antenna 14 RF amplifier
5 load simulator 15 RF signal generator
6 battery 16 power meter
7 test bench (with ground plane if required) 17 directional coupler
8 Rx antenna 18 power sensor
9 tuner controller 19 AN(s) (used with ground plane setup)
10 attenuator
Figure 1 — Example of suitable test facility (top view)
8 Test method
CAUTION — Hazardous voltages and fields may exist within the test area. Care should be taken to
ensure that the requirements for limiting the exposure of humans to RF energy are met.
8.1 Test plan
Prior to performing the tests, a test plan shall be generated which shall include the following, as well as any
special instructions and changes from the standard test:
⎯ test set-up;
⎯ frequency range;
⎯ test frequencies or step sizes;
⎯ DUT mode of operation;
⎯ DUT acceptance criteria;
⎯ test severity levels;
⎯ DUT monitoring conditions;
⎯ test report content.
Every DUT shall be tested under the most significant conditions, i.e. at least in stand-by mode and in a mode
where all the actuators can be excited.
8.2 Test procedure
8.2.1 Setting Up the DUT
Install the DUT, harness and associated equipment in the chamber working volume in accordance with
Clause 7.
8.2.2 Determining chamber loading effects
Prior to the actual testing, determine the loading effects of the reverberation chamber in accordance with
Annex C for each test frequency, including the calculation of the chamber loading factor F and the
CLF
minimum pulse width T that can be sustained by the chamber.
p,min
To determine the loading effects, the field strength may be lower than for the actual testing.
8.2.3 Determining chamber forward power requirements
Calculate for each test frequency the necessary forward power P into the transmitting antenna for the
Forw,Test
required electric field strength using Equation (1):
⎛⎞E
Test
PF= (1)
⎜⎟
Forw,Test CLF
G
⎝⎠RC
where
E is the required field strength, i
...