Update on CISPR Standards
What’s New Above 9 kHz
T
he global recession has
not prevented EMC
standardization work from
marching relentlessly
forward. Work within CISPR is no
exception and this year delegates and
experts will meet in Lyon, France
in September under the auspices of
the current chairman Don Heirman
(US) and secretary Steve Colclough
(UK). For those of you new to EMC,
CISPR is an international special
committee on radio interference within
the International Electrotechnical
Commission (IEC). As defined on
the IEC website for CISPR, CISPR’s
principal task is at the higher end
of the frequency range, from 9 kHz
upwards, preparing standards that
offer protection of radio reception
from interference sources such as
electrical appliances of all types, the
electricity supply system, industrial,
scientific and electromedical RF,
broadcasting receivers (sound and TV)
and, increasingly, IT equipment (ITE).
Following is a brief overview of the
scope of CISPR’s current activities
in 2009, close to 75 years after its
founding in 1935.
BASIC STANDARDS
CISPR Sub-committee (SC) A
provides basic standards to CISPR
product committees as well as other
IEC technical committees for use in
determining conformity to limits.
Activity specifically involves radiointerference measurements and
statistical methods.
CISPR SCA Active Projects Measuring Apparatus
CISPR 16-1-1 has been rewritten
concerning the use of spectrum
analyzers without pre-selection for
compliance measurements.
A new CISPR 16-1-6 project on
antenna calibration was started in the
past year and will update the current
CISPR 16-1-5, add time domain
techniques, and will apply additionally
to frequencies above 1 GHz.
CISPR 16-1-4 and 16-1-5 will be
amended for the introduction of the
Reference Site Method which offers
an improvement on the method of
validation of reference test sites
through the use of the AAPR Antenna
Pair Reference. This AAPR includes the
antenna factors as well as the coupling
of each antenna to the ground plane
and the coupling between the antennas.
In addition, the radiation patterns of
By Martin Wiles
the antennas are included as compared
to the NSA method where the radiation
patterns are approximated Hertzian
dipoles. Round-robin tests have already
provided valuable input and a much
improved second draft is circulating.
Although already included for
frequencies below 1 GHz, the
evaluation of the set up table on the
impact of the EUT emissions can
now be measured and included in the
uncertainty budget also now above
1 GHz in CISPR 16-1-4 Ed 3.0.
Such tables have historically been
made of wood but the above 1 GHz
test will require the use of different
lower reflection dielectric materials.
Experience is still limited but the
market is already starting to see the
emergence of specialised tables to suit
this requirement. The second edition
of CISPR 17 on “Measurement of
EMC Characteristics of RF Filters” is
at second stage Committee Draft (CD).
FEAT U R E Update on CISPR Standards
CISPR SCA Active Projects - Test
Methods
CISPR SC I Information Technology,
Multimedia, and Receiver Products
yy CISPR 16-2-1 Conducted
yy CISPR 13 Broadcast receivers
and associated equipment recently
published; Ed 6.0 included emission
limits to 6 GHz
disturbance measurements
concerning effect of cable bundling
yy CISPR 16-2-3 Addition of
measurand for radiated emissions
less than 1 GHz
yy CISPR 16-2-3 Addition of receiving
antenna height scan above 1 GHz
yy CISPR 16-2-3 Application of
Common Mode Absorbing Device
(CMAD).
CISPR SCA Active Projects Uncertainty
yy CISPR 16-4-1 Treatment of
uncertainties in compliance criteria
yy CISPR 16-4-2 Amendment on
measurement instrumentation
uncertainty
yy CISPR 22 ITE recently published Ed
6.0; included emission limit changes
to 6 GHz
yy CISPR 32 Multimedia is currently
one of the major activities within
CISPR. A first draft of this standard
received over 1000 comments; a
second draft is now circulating
taking into account those comments
as appropriate. Of interest is the
continued debate on a general
level concerning referee or
alternative methods which were
originally highlighted by the first
draft inclusion of chamber, TEM
cell and mode stirred methods
all in the normative section. The
latter two have now been placed
into an informative annex as the
IEC-CISPR national committees
have positioned itself with referee
methods at this time stating that:
“If more than one adequate test
method exists for a characteristic,
only one shall in principle be the
subject of a document. If, for any
reason, more than one test method is
to be standardized, either the referee
(often called “reference”) method
shall be identified in the document
or the intended (equal) validity shall
be stated.”
yy Requirements and Measurement
Methods for Power Line
Telecommunications (PLT)
PRODUCT STANDARDS
CISPR SC B Industrial, Scientific and
Medical (ISM) Standards
yy CISPR 11 – The future Ed 5.0
is currently under revision with
key issues related to harmonizing
methods with CISPR 16
CISPR SC D Vehicle, Boats and
Internal Combustion Engines
Standards
Photo used with permission of ETS-Lindgren
yy CISPR 12 (off board receiver
emissions) and CISPR 25 (on-board
receiver emissions) – Maintenance
continues
CISPR SC F Household Appliances,
Electric Tools and Similar Apparatus
Standards
yy CISPR 14 Consumer (Immunity
and Emission ) – No major work
underway; currently active
yy CISPR 15 Lighting – SC F is
working with SC A on use of
Coupling-Decoupling Networks
(CDN)
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Example of a fully absorber-lined room (FAR) as described in draft standard IEC 61000-4-22,
which may eventually exist in parallel to CISPR 16-1-4 and IEC 61000-4-3. The new draft
standard offers an independent and more efficient method of validating a FAR and EUT
set up for both radiated immunity and emissions EMC testing.
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Update on CISPR Standards
Equipment –The issue is to allow the same level of radio
protection while placing IT signals on the mains cord that
are at the higher levels allowed for mains in the frequency
range 150 kHz to 30 MHz. Presently the rationale for this
work is being prepared. One approach is to have notches in
the PLT spectrum where at those critical frequencies; there
is significant reduction in the applied signal. Such notches
are suggested for the amateur radio band as an example.
CISPR JTF Work
CISPR has setup a number of internal Joint Task Forces
(JTFs) or cross sub-committee groups to facilitate an
improved application of test methods (using the output of
SC A) and better use of the interference model
(provided by SC H).
yy A/D Development of a chamber validation method for
CISPR 25. This will be separated in two parts: (1) below
30 MHz and (2) 30-1000 MHz
yy A/D Inclusion of Fast Fourier Transform (FFT) based
instrumentation in CISPR 16 to use new time domain
based technology
yy A/F CDN measurement - the task is to transfer the
methods for measuring conducted emissions from
luminaries from CISPR 15 into CISPR 16
F EAT U R E
yy IEC 61000-4-21 Ed 1.0: The Reverberation Chambers
JTF has also completed its first maintenance cycle and is
revising to include amongst others: field probe calibration,
immunity and emission methods, and measurement
uncertainty. Currently at the Final Draft International
Standard (FDIS) stage.
yy IEC 61000-4-22: Fully Absorber-lined Rooms (FARs).
After some delay, the second CD of this draft standard
has been sent for Committee Draft for Vote (CDV). The
methods described in this document offer an independent
and more efficient method of validating a FAR and EUT
set up for both radiated immunity and emissions which
could exist in parallel to CISPR 16-1-4 and IEC 610004-3. It has therefore met with some opposition and the
result of the vote is eagerly anticipated within IEC/
CISPR. On a related topic, we are seeing more chamber
users considering retrofits of existing chambers to replace
outdated RF absorber with the newer material available.
On many of these 15+ year chambers, the shielded
enclosure still performs well; however, the absorber may
not have fared so well over the years and performance has
been compromised. An article on one user’s experience
with a major absorber retrofit appears on page 5.
yy A/I Common measurement methods so that the SC I
standards using SC A basic measurement techniques
simply reference them in the product standard; also to
suggest that techniques used in SC I and not in CISPR
16 be added to CISPR 16 so that they can be removed
from SC I publications and simply refer to the CISPR 16
documents
yy A/H Limits, especially those for new measurement
techniques for use by the product committees
IEC SC 77B / CISPR JTF Work
IEC/CISPR has also set up a number of joint task forces
with IEC SC 77B, which is under the Technical Committee
(TC) 77 umbrella. The main task of TC 77 and its three
sub-committees (including SC 77B) is to prepare basic
and generic EMC publications specifying electromagnetic
environments, emissions, immunity, test procedures,
measurement techniques, etc. SC 77B specifically handles
high-frequency continuous and transient phenomena,
including electrostatic discharges, for example. It has the
responsibility for the publication of the following:
yy IEC 61000-4-20: The TEM Cell JTF has completed its first
maintenance cycle and been revised to include field probe
calibration, provision for large EUTs and harmonized test
setups for immunity and emission. Currently FDIS.
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FEAT U R E Update on CISPR Standards
Whilst some of the Sub-committees have been able to
reduce their workload in recent times (in particular SC A)
there has been an increase in the scope of the Joint Task
Force activities which virtually all include SC A. This
is considered a good method to further involve the basic
measurement experts with those in product committees
that use their outputs. This is born from CISPR’s desire
to constantly improve and update all standards whilst
harmonizing and optimizing the work involved. 
FOR MORE INFORMATION
ACKNOWLEDGEMENT
The author wishes to acknowledge and thank Don Heirman,
Chairman of CISPR, for his invaluable review of and
contributions to this article. Mr. Heirman can be contacted at
d.heirman@ieee.org.
Martin Wiles is a Senior RF Engineer with ETS-Lindgren, in
Stevenage, England. He is a UK delegate for CISPR A and the
IEC-CISPR Joint Task Force on Fully Anechoic Rooms. He can
be reached by e-mail at martin.wiles@ets-lindgren.com.
Photo used with permission of ETS-Lindgren
Please consult the IEC website www.iec.ch or contact your
national committee. For more detailed information on the
background of CISPR and its current activities,
visit www.emcs.org/acstrial/newsletters/winter09/
ActivitiesofCISPR.html. This article by Werner Schaefer
(wsemc@cisco.com) was published in the Winter 2009,
Issue 220 of the IEEE EMC Society Newsletter.
A semi-anechoic 10 meter chamber for automotive EMC compliance testing in accordance with CISPR 12, which describes the radio disturbance
characteristics – limits and methods of measurement – for vehicles, boats and internal combustion engine driven devices. Many CISPR 12 chambers may
also be used for testing in accordance with other automotive standards, such as SAE J551 and ISO 11451-2, as well as CISPR 25.
4 IN Compliance Premiere Issue
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WHAT IT TAKES
Considering Refurbishing an Anechoic Chamber?
Guidelines for a Successful Upgrade
Eric Schumann, Advisory Engineer, IBM
A
re you considering refurbishing a Semi Anechoic
Chamber (SAC)? If so, this short sidebar article should
help you. In 2007, IBM refurbished an 18 year old
SAC. The overhaul was a challenging project as it had to
convert the facility designed for an abandoned mission to
a far more complex one testing Enterprise Servers (very
large main frame computer systems). The Normalized Site
Attenuation (NSA) volume doubled. The electrical power
increased from 36 KW to 400 KW. The turntable diameter
expanded to 6.0 meters while its weight capacity went from
3,000 pounds to 25,000 pounds. Finally, HVAC capacity
tripled.
important to understand what the refurbished chamber will
be used for. The project manager must understand what is
going in it and how it will be used. You need to understand
basic physical characteristics such as the EUT’s dimensions,
weight, electrical requirements and HVAC. You should
also forecast future requirements as it is very expensive
to upgrade later. At this point, you have to decide if the
existing SAC can be upgraded for the new mission. There is
no hard and fast answer here; you have to use your technical
knowledge, experience and judgment if it can be upgraded.
Among other factors, Normalized Site Attenuation (NSA)
volume and structural integrity are major considerations.
For IBM, this project was a significant capital investment.
The chamber, at some 80’ long x 45’ wide x 29’ high, still
performed well; however, the absorber did not fare so well
over time. In addition, considerable advances in absorber
performance since the chamber was installed 18 years ago
made refurbishment a practical consideration. Investing in
new absorber and refurbishing our existing chamber made
sense in our case. Given the multi-million dollar amount of
this refurbishment, however, we had to be thorough in our
process to select the optimal contractor. Hopefully, you can
benefit from our experience!
If your engineering judgment is “yes,” then it is time to call in
potential contractors. Have your test requirements firm and
crisp. Dig out the original blueprints; these are most helpful
for the bidders. Better yet, have copies available.
Building a new SAC or refurbishing an old one is a detailed
technical construction project. First and foremost, it is very
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After all the contractors reviewed the existing SAC, IBM had
extensive discussions with them over an extended period
since this was a technically challenging project that pushed
the limits of the current facility. We wanted to insure that
the contractors understood what IBM wanted and, in fact,
could do the transformation. IBM had two major concerns:
EUT volume and turntable structural integrity. The diameter
of the turntable would increase to 6.0 meters and come
close to the potential edge of anechoic material. In addition,
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WHAT IT TAKES
the floor to ceiling height would decrease by 12 inches.
The larger turntable and smaller height affects Normalized
Site Attenuation. The other major concern was the new
turntable’s larger diameter and increased weight capacity.
In addition, we had extensive discussions on how Enterprise
Servers would be tested with their numerous signal and
power cables. Also, some products are cooled with chilled
water; we had to contend with
fairly inflexible hoses. These
detailed discussions ensured the
EMC Lab personnel could test
with ease.
AND measured results of the proposed absorber. Also, it
is important that the bidders know what antennas and
instrumentation you use. In the contract, you should specify
an NSA margin and decide how the final performance test
should be conducted.
Important to refurbishments is a shielding effectiveness
test (SE) with 100 dB being standard performance. It is
important to patch up leaks.
Chances are that the facility
has many “untreated”
penetrations. In IBM’s case, we
saw light through one! Usually
the SE test is performed just
before the anechoic material
is applied. There will be some
areas where you will not
achieve the 100 dB performance
level. You need to understand
when penetrations for electrical,
light, HVAC and signals are
performed. A second SE test may be necessary.
“It is a good idea to be mindful
of the local construction codes
and the building inspectors who
enforce them. If you are not,
these folks can stop you cold!”
As you are having these
discussions, it is important to
understand that each contractor
has proprietary techniques,
information and insight. We
went to extensive lengths to
ensure there was no “cross
contamination” between the bidders. Each one had unique
insights about the project, but we did not share such
information with others.
Once these discussions are finished and you are confident
that all potential contractors understand what is required,
you can develop a uniform bid document. Such a bid
document will contain both a written description and
drawings. Remember, the bid becomes a legal contract
upon acceptance so make sure all details are included and
accurate.
The following discussion is pertinent to both new
construction and refurbishment. However, these items were
of particular interest to the refurbishment project.
NSA performance is most critical. If the refurbished chamber
does not pass the Normalized Site Attenuation requirement,
it can not be legally used for product certification work.
It is that important. In IBM’s case, the new test volume
was so large that it came close to the anechoic foam tips.
IBM’s Distinguished Engineer, Dr. Bruce Archambeault,
modeled the SAC¹. Most buyers cannot do this. Because
of the considerable investment in the new absorber, Dr.
Archambeault modeled the predicted performance of the
new absorber and required that all bidders provide modeled
data with documentation of actual measurements to verify
the accuracy of the modeling. If you do not have someone
on staff that is skilled in modeling, you should ask your
bidders for a comparison report showing the predicted
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Be sure to understand the fire protection service your
insurance carrier requires and incorporate this in the bid
package. There is a good chance that the requirements
are more stringent then what was originally required.
Understand that fire heads impact NSA performance.
It is a good idea to be mindful of the local construction codes
and the building inspectors who enforce them. If you are
not, these folks can stop you cold!
I could go on but space limitations force me to stop. The
most important advice that I can offer is that a chamber
overhaul is a detailed technical construction project. You
need to stay on top of budgets, schedules, the contract,
the prime bid winner and all their subcontractors - not to
mention your own company’s requirements. You have to
play well with others. There is no magic bullet; just plain
hard work to ensure success. But if you do, you will have a
successful project. The original chamber lasted 18 years; we
hope the refurbished one lasts as long.
For further information, please contact the author at
ericrs@us.ibm.com or at phone: 919-543-5397.
¹ Dr. Archambeault’s modeling report showing
predicted versus actual measured performance of the new
absorber material installed in IBM’s chamber
can be read starting on page 7.
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SPECIAL REPORT
Site Attenuation Prediction for
Refurbishing an Older EMC Chamber
Bruce Archambeault, Sam Connor, Eric Schumann
IBM
The IBM RTP/065 EMC Chamber
required a refurbishment in order
to accommodate larger computer
systems. One of the planned
enhancements was to replace the
existing carbon-loaded foam RF
absorbers with a combination of
ferrite tile and RF absorber. This
report analyzes the site attenuation
characteristics of the proposed
chamber with supplier provided RF
absorber loss data.
Information directly from vendor
proposals showed simulations had
indicated that the site attenuation
values were right on the +/- 4 dB limit
required by the EMC regulatory bodies.
This work was intended to increase/
decrease confidence in the likelihood
that the new chamber would meet
the necessary site attenuation limits.
Due to business concerns, senior
IBM management decided that there
was no room for error and that the
7 IN Compliance Premiere Issue
newly refurbished chamber must be
operational on schedule.
While proposals and data from more
than one supplier were included in
the original analysis, only the chosen
supplier1 results will be included here
(since they ultimately won the contract
with IBM).
SIMULATION TECHNIQUE
The basic simulation technique used
for this analysis is ray-tracing. It is
assumed that the first reflection is
the major reflection and there is
one reflection from each wall. The
amplitude and phase of the path
includes the free-space loss/phase
as well as the loss/phase from the
absorber material. Supplier provided
absorber information is used in all
cases (with reflection being dependant
1
on approach angle and frequency).
Free-space loss is based on 1/r
distance.
SITE ATTENUATION
SIMULATION
The requirements for site attenuation
include the following:
1. All combinations of direct ray
and reflected rays must have a
maximum of no more than +/- 4 dB
from theoretical (direct with one
reflection from the metal floor) as
the receive antenna is scanned in
height from 1 meter to 4 meters
above the metal floor.
2. The source antenna must be placed
in five different locations on the
turntable (center, along turntable
edge nearest to receive antenna,
along turntable edge furthest from
The chosen supplier was ETS-Lindgren in Cedar Park, Texas. For additional information,
please contact the supplier or the author at bruce.arch@ieee.org.
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SPECIAL REPORT
receive antenna, and at remaining
90 degree offsets along turntable
edge. The source antenna heights
will be one meter and two meters
for horizontal polarization and one
meter and 1.5 meters for vertical
polarization. The receive antenna
must be maintained at 10 meter
distance from the source antenna.
SITE CONFIGURATION
Figure 1 shows the general site
configuration for the enclosure. The
non-rectangular shape potentially
changes the site attenuation prediction
from the suppliers, since their tools only
operate with rectangular enclosures.
The basic internal dimensions of the
metal walls are 44 feet wide by 80 feet
long. Also shown is the turntable size
change from the previous 4.5 meter to
6 meter diameter. The ceiling height is
25 feet from the metal floor.
Figure 2 shows the chamber
configuration with the larger turntable
moved towards the left end by one foot
(as proposed by the chosen supplier).
Figure 1 Chamber Configuration with Larger Turntable Centered at Previous Location
Figure 2 Chamber Configuration with Larger Turntable Moved from Previous Location by
One Foot
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SPECIAL REPORT
Figure 3 Site Attenuation Antenna Locations
for Centered Receive Antenna
Figure 6 Reflection Loss for One Meter Cones (TM)
Figure 4 Site Attenuation Antenna Locations
for Offset Receive Antenna
Figure 7 Reflection Loss for 1.5 Meter Cones (TE)
Figure 5 Reflection Loss for One Meter Cones (TE)
Figure 8 Reflection Loss for 1.5 Meter Cones (TM)
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SPECIAL REPORT
Figure 9 Predicted Site Attenuation Deviation
for Offset Receive Antenna
Horizontal Polarization and One Meter High Source Antenna
Figure 12 Predicted Site Attenuation Deviation
for Offset Receive Antenna
Vertical Polarization and 1.5 Meter High Source Antenna
Figure 10 Predicted Site Attenuation Deviation
for Offset Receive Antenna
Horizontal Polarization and Two Meter High Source Antenna
Figure 13 Predicted Site Attenuation Deviation
for Centered Receive Antenna
Horizontal Polarization and One Meter High Source Antenna
Figure 11 Predicted Site Attenuation Deviation
for Offset Receive Antenna
Vertical Polarization and One Meter High Source Antenna
Figure 14 Predicted Site Attenuation Deviation
for Centered Receive Antenna
Horizontal Polarization and Two Meter High Source Antenna
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SPECIAL REPORT
ANTENNA LOCATIONS FOR SITE ATTENUATION
CONCLUSION
Figure 3 shows the chamber configuration with the five
transmit antenna locations shown on the turntable for the
case where the receive antenna is located along the center
line of the chamber. The proposals from the suppliers only
allowed for the center line position of the receive antenna.
However, IBM typically uses the receive antennas offset, so
there can be two antennas being used simultaneously (for 30200 MHz and for 200-1000 MHz). This desired configuration
for antenna placement is shown in
Figure 4.
All the simulation results showed a reasonable margin for
the predicted site attenuation from both supplier proposals.
While the supplier proposals were at the limit of +/- 4dB, it is
believed that they were being overly conservative and adding
extra margin in their predictions (since their simulation
tools could not directly handle the non-rectangular shape of
the room and the non center line placement of the receive
antennas).
SITE ATTENUATION PREDICTION WITH THE
CHOSEN SUPPLIER’S PROPOSAL
The proposal from the chosen supplier included ferrite tiles
and cone absorber material. The three walls behind the
receive antennas had 1 meter thick cones, and all other walls
and the ceiling had 1.5 meter thick cones.
The refection loss from the supplier is shown in Figures 5 and
6 for the one meter cones and Figures 7 and 8 for the 1.5
meter cones.
The site attenuation requirement is to have the actual
received signal be within +/- 4 dB of the theoretical
value from a direct ray and one reflection from a perfect
‘ground’ plane. Figures 9 through 16 show the predicted
site attenuation using the absorber reflection data from
the chosen supplier, and assuming one reflection from
each of the eight walls. Both centered and offset receive
antenna positions are included. All cases meet the +/- 4 dB
requirement with a comfortable margin.
Figure 15 Predicted Site Attenuation Deviation
for Centered Receive Antenna
Vertical Polarization and One Meter High Source Antenna
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These predictions were based on the supplier provided
data for their absorber materials. Both suppliers that bid
the IBM project had experienced and well known engineers
responsible for their data, and confidence was high that the
data from both companies was accurate.
The final conclusion from this analysis was that there was a
comfortable margin with the data from either supplier. The
final decision on supplier selection was not dependant on the
technical performance.
Once the project was completed, the actual testing showed
the site attenuation test results met the required +/- 4 dB
requirement with a comfortable margin.
Dr. Archambeault’s modeling report showing predicted versus
actual measured performance of the new absorber material
installed in IBM’s chamber can be seen online at
www.incompliancemag.com/absorber_data.
Figure 16 Predicted Site Attenuation Deviation
for Centered Receive Antenna
Vertical Polarization and 1.5 Meter High Source Antenna
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