SIST R210-010:2003

Electromagnetic compatibility - Emission measurements in fully anechoic chambers

D124/093: To be converted into TS

Elektromagnetische Verträglichkeit - Störaussendung in Absorberräumen

Compatibilité électromagnétique - Émission en chambres anéchoïques entiers

Electromagnetic compatibility - Emission measurements in fully anechoic chambers

General Information

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.100.10 - Emission
• Technical Committee: EMC - Electromagnetic compatibility
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Directive: 89/336/EEC - Electromagnetic compatibility (EMC)
• Ref Project: R210-010:2002 - Electromagnetic compatibility - Emission measurements in fully anechoic chambers

Relations

• Replaced By: SIST-TP CLC/TR 50485:2011 - Electromagnetic compatibility - Emission measurements in fully anechoic chambers
• Effective Date: 01-Dec-2011

Overview

R210-010:2002 (CENELEC / CLC) is a technical report on Electromagnetic Compatibility (EMC) covering radiated emission measurements in Fully Anechoic Rooms (FARs). The report applies to measurements in the frequency range 30 MHz to 18 GHz, with the document specifically covering 30 MHz–1 GHz; frequencies above 1 GHz were noted as under consideration at the time. This standard describes FAR validation, measurement setup and procedures, and guidance for relating FAR results to common Open Area Test Site (OATS) limits. Note: R210-010:2002 is superseded by CLC/TR 50485:2010.

Key topics and requirements

• FAR definition and purpose: shielded enclosures lined with RF absorbing material to simulate free‑space propagation (minimise reflections and external interference).
• Frequency scope: primary coverage 30 MHz–1 GHz; methodology intended for up to 18 GHz but higher bands require further experience.
• Room validation (NSA approach):
  • Use of Normalised Site Attenuation (NSA) and Site Attenuation (SA) as validation metrics.
  • Validation requires SA/NSA measurements at 15 positions (three heights × five horizontal positions) and both polarizations - resulting in 30 measurements.
  • Transmit antenna for validation should approximate omnidirectional pattern and have a maximum dimension of 40 cm (e.g., biconical).
• Test and measurement equipment: compliance with CISPR 16 requirements; use of linear‑polarized broadband antennas (biconical, LPDA, hybrid) and free‑space antenna factors.
• Test setup guidance: EUT placement, test volume definition (cylindrical region around EUT), test distance, cable layout and terminations, and test plan/reporting requirements.
• Chamber performance metrics: shielding (per EN 50147-1), absorber placement, uncertainties comparison with 3 m OATS (Annex C), and additional informative annexes (site reference, limit values, corrections, balun imbalance, etc.).

Applications

• Alternative method to OATS for radiated emission compliance testing of electronic equipment.
• Validation and commissioning of FARs / EMC chambers for test laboratories.
• Supporting measurement uncertainty assessments and translating FAR results to standard limits (e.g., EN 55011, EN 55022).
• Useful in product compliance testing for manufacturers of IT equipment, industrial/ISM devices, and components subject to EMC regulations.

Who uses this standard

• EMC test laboratories and accreditation bodies
• Chamber designers and builders
• Compliance engineers and product test teams
• Standards committees and product working groups defining emission limits

Related standards

• CISPR 16 (parts 1–3)
• EN 50147-1 (shield attenuation measurement)
• EN 55011, EN 55022 (product emission limits)
• ISO/IEC 17025, ANSI C63.4 / C63.5

Keywords: electromagnetic compatibility, EMC, radiated emissions, fully anechoic chamber, FAR, NSA, site validation, OATS, antenna factor, chamber validation.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2003
Electromagnetic compatibility - Emission measurements in fully anechoic
chambers
Electromagnetic compatibility - Emission measurements in fully anechoic chambers
Elektromagnetische Verträglichkeit - Störaussendung in Absorberräumen
Compatibilité électromagnétique - Émission en chambres anéchoïques entiers
Ta slovenski standard je istoveten z: R210-010:2002
ICS:
33.100.10 Emisija Emission
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CENELEC R210-010
REPORT June 2002
English Version
Electromagnetic compatibility -
Emission measurements in fully anechoic chambers
Compatibilité électromagnétique - Elektromagnetische Verträglichkeit -
Émission en chambres anéchoïques Störaussendung in Absorberräumen
entiers
This CENELEC Report has been prepared by TC 210, Electromagnetic compatibility (EMC). It
was approved by TC 210 on 2001-11-13 and was endorsed by the CENELEC Technical Board
on 2002-03-05.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg,
Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. R210-010:2002 E
R210-010: 2002 - 2 -
Foreword
This Technical Report has been prepared by the joint WG 4 of CENELEC TC 210, Electromagnetic
compatibility, and SC 210A, EMC Products.
It was approved for publication by the CENELEC Technical Board on 2002-03-05.
_____________
Contents
1 Scope.3
2 References .3
3 Definitions and abbreviations .4
3.1 Definitions.4
3.2 Abbreviations.5
4 Test and measurement equipment.5
4.1 Fully Anechoic Rooms (FARs).5
4.2 Antenna .5
5 Anechoic Room performance.5
5.1 Theoretical normalised site attenuation .5
5.2 Room validation procedure.7
5.3 Anechoic room requirements.11
6 Emission measurement.11
6.1 Test set up.11
6.2 EUT position .12
6.3 Cable layout and termination.14
7 Test procedure.15
8 Test plan.15
9 Test report.16
Annex A Determining the Site Reference .17
Annex B (informative) Limit values.19
Annex C (informative) Comparison of measurement uncertainties for 3 m OATS and
3 m FAR.25
Annex D (informative) Derivation of free space NSA formula.30
Annex E (informative) Corrections of field strength for test distance.33
Annex F (informative) NSA measurements with biconical antennas .35
Annex G (informative) Measurement of Balun imbalance .38
Annex H (informative) The FAR project .39

- 3 - R210-010: 2002
1 Scope
This technical report applies to emission measurements of radiated electromagnetic fields in Fully
Anechoic Rooms in the frequency range from 30 MHz to 18 GHz. This report covers the frequency
range from 30 MHz – 1000 MHz. The frequency range above 1 GHz is under consideration, due to the
absence of practical experience.
This report describes the validation procedure for the Fully Anechoic Room (FAR) for radiated
emission tests and the procedures to carry out the tests (e.g. test set up, EUT position, cable layout
and termination, test procedures). Recommendations for the relation between FAR emission limits and
common Open Area Test Site (OATS) emission limits given in standards such as EN 55011 and
EN 55022 are given in Annex B.
This FAR emission method may be chosen by product committees as an alternative method to
emission measurement on an Open Area Test Site (OATS) as described in CISPR 16. In such cases,
the product committee should also define the appropriate limits. Typical measurement uncertainty
values for FARs and OATS are given in Annex C.
2 References
This technical report incorporates by dated or undated reference, provisions from other publications.
These references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this European Standard only when incorporated in it by amendment or revision. For undated
references the latest edition of the publication referred to applies (including amendments).
Publication Title
CISPR 16-1 Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1: Radio disturbance and immunity measuring apparatus
CISPR 16-2 Specification for radio disturbance and immunity measuring apparatus and
methods – Part 2: Methods of measurement of disturbance and immunity
CISPR 16-3 Reports and recommendations of CISPR
EN 50147-1 Anechoic chambers – Part 1: Shield attenuation measurement
EN 55011 Industrial, scientific and medical (ISM) radio-frequency equipment – Radio
disturbance characteristics – Limits and methods of measurement (CISPR 11,
mod.)
EN 55022 Information technology equipment – Radio disturbance characteristics - Limits
and methods of measurement (CISPR 22, mod.)
IEC 60050-161 International Electrotechnical Vocabulary (IEV) – Chapter 161: Electromagnetic
compatibility
ISO/IEC 17025 General requirements for the competence of testing and calibration
laboratories
ANSI C 63.4/ American national standard for methods of measurement of radio-noise
emissions from low voltage electrical and electronic equipment in the range of
9 kHz – 40 GHz
ANSI C 63.5 Electromagnetic compatibility – Radiated emission measurements in
Electromagnetic Interference (EMI) control – Calibration of antennas

R210-010: 2002 - 4 -
3 Definitions and abbreviations
3.1 Definitions
For the purpose of this technical report, the following definitions and the definitions contained in
IEC 60050-161 apply.
3.1.1
Fully Anechoic Room (FAR)
shielded enclosure whose internal surfaces are lined with radio frequency absorbing material (i.e.
RAM), that absorbs electromagnetic energy in the frequency range of interest.
NOTE The fully Absorber-Lined Room is intended to simulate free space environment.
3.1.2
Equipment Under Test (EUT)
test sample including connected cables.
NOTE The EUT may consist of one or several pieces of equipment.
3.1.3
test volume
region of the Room that meets the NSA requirements of this technical report and which contains the
EUT as fully set up
3.1.4
free space antenna factor (AF )
FS
antenna factor of an antenna which is not affected by mutual coupling to conducting bodies in the
environment of the antenna
NOTE It is also the antenna factor measured when the antenna under test is illuminated by a plane wave, which implies
that the source antenna is in the far-field of the antenna under test. Antenna factor is defined as the ratio of the magnitude of
the E-field in which the antenna is immersed to the voltage at the antenna output of a given transmission line impedance,
usually 50 �.
3.1.5
antenna reference point
physical position on the antenna from which the separation distance to the defined reference plane on
the EUT is measured
NOTE For dipole and biconical antennas this will be the centre of the antenna in line with the central antenna elements. For an
LPDA antenna and a hybrid antenna, the reference point is the mark on the antenna provided by the manufacturer for this
purpose. The reference point is approximately at the mid-way point between the array elements that are active at the top and
bottom frequencies at which the measurements are being made. Hybrid antenna is here defined as a combination of a biconical
and LPDA antenna which has a frequency range including 30 MHz to 1 GHz.
3.1.6
Normalised Site Attenuation (NSA)
site attenuation obtained from the ratio of the source voltage connected to a transmitting antenna and
the received voltage as measured on the receiving antenna terminals
NOTE Normalised site attenuation is site attenuation in decibels minus the antenna factors of the transmit and receive antenna
factors. NSA was first introduced for evaluation of open area test sites with ground planes and was measured by height
scanning the receive antenna. In this technical report, NSA is measured in a quasi-free space environment, and because there
is no deliberate ground plane height scanning is not required.
3.1.7
test distance (d )
t
distance measured from the reference point of the antenna to the front of the boundary of the EUT

- 5 - R210-010: 2002
3.2 Abbreviations
EUT Equipment Under Test
FAR Fully Anechoic Room
NSA Normalised Site Attenuation
AF antenna factor (free space)
FS
LPDA Log-Periodic Dipole Array
OATS Open Area Test Site
RS reference site
SA
site attenuation
SA measurement of SA made on RS
R
NEC Numerical Electromagnetic Code
4 Test and measurement equipment
Equipment in accordance with CISPR 16 shall be used.
4.1 Fully Anechoic Rooms (FARs)
A Fully Anechoic Room is required for the emission testing in which the radiated electromagnetic
waves propagate as in free space and only the direct ray from the transmitting antenna reaches the
receiving antenna. All indirect and reflected waves shall be minimised with the use of proper absorbing
material on all walls, the ceiling and the floor of the FAR.
The screening of the FAR shall have an adequate attenuation level to avoid outside electromagnetic
radiation entering the Room and influencing the measurement results. The shield attenuation is
measured in accordance with EN 50147-1. Shielding recommendations are given in the technical
report 'recommendation on shielded enclosures'.
4.2 Antenna
Linear polarised antennas shall be used to measure the emitted electromagnetic field of the EUT.
Biconical or log-periodic antennas and hybrid antennas are typical antennas used. The free space
antenna factor shall be used. CISPR 16-3 clause 4.7 gives parameters of broadband antennas.
However no length limitation on LPDA or hybrid antennas is given. Subclauses 5.5.4 and 5.5.5 of
CISPR 16-1 give information on antennas. Subclause 5.5.5.2 states “it is essential that the variation of
the effective distance of the antenna from the source and its gain with frequency be taken into
account”. Antennas over 1,5 m in length could increase the uncertainties of emission testing using a
separation of 3 m between the reference point of the antenna and the front of the EUT.
5 Anechoic Room performance
5.1 Theoretical normalised site attenuation
The Site Attenuation (SA) is the loss measured between the connectors of two antennas on a
particular site. For a free space environment the SA (in dB) can be defined by Equation 1 (see
Annex D):
R210-010: 2002 - 6 -
� �
� �
� �
� �
� �
� �
� 5Z � d
(1)
O
SA � 20log � 20log f � AF � AF ��dB
� �� �
10� � 10 m R T
2�
� �� 1 1 �
� �
1� �
� �
2 4
� �
� �
���d ���d
� �
� �
where AF and AF are the antenna factors of the receive and transmit antenna in dB/m, d is the
R T
distance between the reference points of both antennas in meters, Z is the reference impedance (i.e.
50 �), ß is defined as 2�/� and f is the frequency in MHz.
m
The theoretical Normalised Site Attenuation (NSA) in dB is defined as site attenuation with respective
antenna factors subtracted, thus:
� �
� �
� �
� �
� �
� �
� 5Z � d
O
� �
NSA � 20log � � � 20log f (2)
� �
calc 10 10 m
� �
2� � �
�� � 1 1 �
1� �
� �
� �
2 4
� �
���d ���d
� �
� �
� �
-10
-20
30 m
-30
10 m
5 m
-40
3 m
-50
10 100 1000 10000 100000
Frequency [MHz]
Figure 1a - Plot of theoretical NSA values in free space for far field conditions (Equation 3)
In far-field conditions Equation 2 simplifies to Equation 3 by omitting the near field terms:
� 5Z d �
O
(3)
NSA � 20log � 20log f
calc 10 10 m
� �
2�
� �
NSA [dB]
- 7 - R210-010: 2002
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
2.3
-1.4
0 2 4 6 8 10 12 14 16
Separation, m
Figure 1b - Difference in theoretical NSA between Equation 2 and Equation 3
Distances relate to a frequency of 30 MHz
Using the simplified equation (Equation 3) the error is less than 0,1 dB at frequencies above 60 MHz
for 5 m distance and above 110 MHz for 3 m distance. Figure 1b shows the worst case near-field error
which is at 30 MHz. However at higher frequencies there are Fresnel zone errors for large antennas
which is treated in Annex F.
Equation 1 and Equation 2 account for near field effects of small antennas. In this context, using a
transmit antenna less than 40 cm long, near-field effects become significant (> 0,2 dB) where the
receive antenna length is greater than a quarter of the separation distance. This assumes the use of a
1,4 m long biconical antenna at 300 MHz. The graph in Annex F shows that the error is less than
0,2 dB for a separation of 3 m and a maximum frequency of 200 MHz (it is common to change to a log
antenna above 200 MHz). To cater for the general use of antennas (biconicals up to 300 MHz, or
bilogs), the site reference method (6.2.1 and Annex A) shall be used for chamber validation at
distances up to 5 m. In this method the site attenuation measured in the FAR are compared to those
measured on a free space reference site.
5.2 Room validation procedure
The test volume must meet the Room requirements given in 5.3. The shape of the test volume will be
a cylinder, due to the rotation of the EUT on a turntable. The minimum height and diameter of the test
volume shall be 1 m. The height and diameter do not have to be equal between the maximum and
minimum values.
A single SA measurement is insufficient to pick up possible reflections from the construction and/or
absorbing material comprising the walls, the floor and the ceiling of the Fully Anechoic Room.
In validating the Fully Anechoic Room SA measurements shall be performed at 15 measurement
points for horizontal and vertical polarisation of the antennas:
1) at three heights of the test volume: bottom, middle and top of test volume
2) at five positions in all three horizontal planes: the centre, left, right, front and back position of
the horizontal plane
Difference, dB
R210-010: 2002 - 8 -
For SA measurements, two broadband antennas shall be used: one transmit antenna at the
measurement points of the test volume and one receive antenna outside this test volume at a
prescribed orientation and position. The transmit antenna shall approximate an omnidirectional
antenna pattern and shall have a maximum dimension of 40 cm. Typical antennas are biconical
antennas. The receive antenna used during the Room validation shall be of the same type as the
receive antenna used during radiated emission testing of the EUT.
The frequency range 30 MHz to 1 GHz can be covered with one antenna, a hybrid antenna. The
measurement results may be different if separate biconical and LPDA antennas are used.
For FAR validation the receive antenna shall be in the position of the middle level of the test volume
as shown in Figure 2 and operated in horizontal and vertical polarisation. The distance between
reference points of the receive and transmit antenna shall be d . The height of the measurement
nominal
volume is less than the height of the test volume by the height of the transmit antenna. This is in order
that the tip of the vertically polarised transmit antenna does not protrude above the top plane or below
the top plane of the test volume. This treatment has not been applied, by reducing the diameter, to the
horizontally aligned antenna, because it is room height rather than width which is at issue.
When varying the transmit antenna to the other positions of the test volume the receive antenna shall
be moved to d . In all positions and polarisation the antennas shall face each other (receive
nominal
antenna tilted). When the transmit antenna is placed in the upper and bottom level, the receive
antenna remains in the middle level. The transmit antenna is moved to all 15 positions, the 30 site
validation measurements are performed. Tilting of the antennas implies that only one site reference
measurement is needed to cover all 15 positions.
The back-position does not need to be taken into account if the distance between the boundary of the
test volume and tips of the absorber is more than 1 m. Experiments and modelling have shown that
this distance could be reduced to 0,5 m and further work may be needed to confirm this.

- 9 - R210-010: 2002
Figure 2 – Measurement points in room validation procedure
For each measurement the frequency range is incrementally swept. The frequency step size shall not
exceed 1% and need not be less than 1 MHz as given in Table 1.
Table 1 - Frequency ranges and step sizes
Frequency range Maximum Frequency step
MHz MHz
30 – 100 1
100 – 500 5
500 – 1000 10
For validating the Room performance, two methods exist:
1) the site-reference method, preferred for a test distance up to 5 m
2) the NSA-method, preferred for test distances larger than 5 m
NOTE With reference to the site reference method, achieving quasi-free space conditions requires expertise. The problem is in
sufficiently eliminating reflections from the ground. In practice this probably confines the site reference method as described in
Annex A to distances of less than 5m. On the other hand there are also limitations with the NSA method in that the free space
antenna factor is used. At 3 m distance the antenna coupling is not negligible and expertise is required to correct the free space
antenna factor for coupling. A practical solution is to confine the NSA method to distances greater than 5 m. Corrections, such
as to phase centre, are required, but this can be done precisely.

R210-010: 2002 - 10 -
The intention of the SA measurement is to give "0 dB" deviation on an ideal site. Any measure can be
taken to improve the measurement accuracy as long as it is not contradictory to the described setup
and procedure and does not hide any bad Room performance (e.g. smoothing).
The accuracy in the validation procedure can be improved by the following measures:
1) The cables are extended by at least 2 m behind each antenna before dropping the cable to the
ground for a vertically polarised antenna. The cables will - if possible - extend straight back to
the bulkhead connectors in the wall of the room. Additional possibilities are ferrite rings around
cables.
2) Any bad match of the antennas is padded out by use of attenuators at the antenna connectors
(e.g. 6 dB or 10 dB).
3) Antennas with a good balance of the balun shall be used, giving a change in receiver reading
of less than � 0,5 dB when the illuminated antenna is inverted with respect to its input cable
(see Annex G).
4) The directional pattern of the receive antenna can be accounted for on site validations with the
NSA method.
The Room validation procedure shall be applied at a regular interval (to detect long-term changes in
Room characteristics) and when changes in the Fully Anechoic Room are implemented or occurred,
that might influence the electromagnetic wave transmission characteristics of the Room.
5.2.1 The site reference method
The SA measurement of the antenna pair (transmit and receive antenna) on a quasi free space test
site is required as reference. The antenna pair that is used for site validation is calibrated as a pair on
a reference site. In Annex A the procedure of determining this Site Reference (SR) is described. This
method accounts for coupling of the antennas and near field effects which can have a significant
influence at a 3 m test distance, reducing as the distance increases to 5 m.
The site validation for each measurement point is performed in three steps:
1) The insertion loss (M ) is measured in dB with the cables connected together.
2) The transmission loss (M ) is measured in dB with the cables connected to the antennas.
3) The deviation of the measured site attenuation from site reference is calculated according
Equation 4:
(4)
Dev � M � M � SR�d�
0 1
5.2.2 The NSA method
The NSA method is recommended for distances equal to or greater than 5 m. The free space antenna
factors of the transmit and receive antenna are required for this procedure. The theoretical NSA is a
simple calculation between point sources, and therefore does not account for the radiation patterns of
the actual antennas used. As the transmit antenna is moved throughout the volume it will be slightly
off the boresight direction of the receive antenna. The effects of the radiation pattern are small and
can be corrected for assuming the pattern is that of a Hertzian dipole, or cos �. The phase-centre
variation of log.-periodic and bicon.-log.-periodic antennas have also to be taken into account –
see 6.1.
The site validation for each measurement point is performed in four steps:
1) The insertion loss (M ) is measured in dB with the cables connected together.
2) The transmission loss (M ) is measured in dB with the cables connected to the antennas.
- 11 - R210-010: 2002
3) The measured NSA (NSA ) is calculated in dB according to Equation 5:
m
(5)
NSA � M � M � AF � AF in dB
m 0 1 T R
AF and AF are free space antenna factors in dB/m.
T R
4) The deviation of the measured NSA (Equation 5) from the theoretical NSA (Equation 2) is
calculated according to Equation 6. NSA is given by equation 2 in 5.1.
calc
NOTE The real distance d between the reference points of the transmit and receive antenna has to be used in
Equation 2, not the nominal test distance d . i.e. if the LPDA antenna has been calibrated at its true phase centre
nominal
at each frequency, a phase centre correction must be included if a fixed distance (to the reference point on the LPDA)
is used.
Dev � NSA � NSA in dB (6)
calc m
5.3 Anechoic room requirements
A measurement site shall comply with the two following requirements:
1) the Room validation procedure shall provide deviations which are within � 4 dB of the site
reference values (or the theoretical NSA values for the NSA method) for both horizontal and
vertical polarisation and for the test volume intended to be occupied by the EUT.
2) the maximum diameter and height of the EUT is equal or less than the test distance divided by
2. This requirement ensures acceptable uncertainties in EUT emission testing. These include
distance variation to the emission source, antenna directivity and near field effects. The
maximum diameter as a function of 3 test distances is given in Table 2.
Table 2 - Relation between maximum diameter of EUT and test distance
Maximum diameter and Test distance
height of EUT
1,5 m 3,0 m
2,5 m 5,0 m
5,0 m 10,0 m
The uncertainty budget of the site evaluation measurement shall be available.
6 Emission measurement
6.1 Test set up
The same type of antenna shall be used for EUT emission testing as the receive antenna used for
Room validation testing. The antenna height is fixed at the geometrical centre height of the test
volume. The test distance is measured from the reference point of the antenna to the boundary of the
EUT. In the case of a difference between the reference point on an antenna and the phase centre, a
correction factor, C dB, shall be applied to obtain the field strength at the test distance (see Annex E).
R
(6.1a)
C � 20log��d � P � R� d�
R f
E-field strength is given by Equation 6.1b:
(6.1b)
E � V � AF � C
f f FS( f ) R
R210-010: 2002 - 12 -
The correction factor C is only applicable if the calibration distance is different from the measurement
R
distance.
where:
f
= frequency, (MHz).
d
= the required separation from the source to the reference point (m).
Pf = phase centre position as a function of frequency, (m from tip of the LPDA).
R = distance of the LPDA reference point from the antenna tip (m).
E = E-field at distance R from source (dBV/m).
f
V = voltage at output of antenna at frequency f (dBV).
f
AF
FS(f) = antenna factor (free space) for E-field at the phase centre (dB/m).
C = phase centre correction factor
R
Figure 3 illustrates a typical test set up.
a
Test volume
b X
EUT volume
80 cm
X
Antenna
EUT
box EUT cabling
1)
80 cm
X
A
h d
m
e
Ferrite
c
clamp 2)
A: turntable and EUT-support
2X:
1,5 m; 2,5 m , 5 m
h : middle level of the test volume
m
d: 3 m; 5 m or 10 m
a, b, c and e:
� 0,5 m recommended (� 1 is discretionary)
1): The antenna cable layout shall be the same as in the validation procedure
2): Ferrite clamp under consideration
Figure 3 - Typical test set-up in FAR, where a, b, c and e depend on the room performance
The EUT shall be placed on a turntable to enhance the emission testing procedure. The turntable can
be arranged above the floor absorbers. The turntable, antenna mast and any supporting floor material
shall be transparent to electromagnetic waves (relative permitivity, є , as near to one as practicable).
r
6.2 EUT position
The EUT shall be configured, installed, arranged and operated in a manner consistent with typical
applications. Interface cables shall be connected to each type of interface port of the EUT.

- 13 - R210-010: 2002
If the EUT consists of separate devices the space between the devices shall be in normal
configuration but with 10 cm separation if possible. Interconnecting cables shall be bundled and
separated from each other. The bundle shall be around 30 to 40 cm long and longitudinal to the cable.
Ancillary equipment, which is required to exercise the EUT but does not form part of the EUT, shall be
located outside the screened room.
The entire EUT shall fit in the test volume.
To improve the measurement repeatability, the following guidelines shall be taken into account:
1) Smaller table-top equipment (including cabling) will be placed in the geometrical centre
(horizontally and vertically) of the calibrated volume (see Figure 4).
2) The bottom of larger table-top equipment (Figure 5) and floor standing equipment will coincide
with the bottom of the test volume.
Figure 4 and Figure 5 illustrate the set up of several types of EUT’s in the Fully Anechoic Room. Work
is in progress to decide the appropriate termination condition for cables exiting the volume. Ferrite
clamps are shown here for purposes of illustration.
Test volume
X
EUT volume
80 cm
X
Antenna
EUT
EUT cabling
1) box
80 cm
X A
d
Ferrite
clamp 2)
A: turntable and EUT-support
2X: 1,5 m; 2,5 m , 5 m
d: 3 m; 5 m or 10 m
1): The antenna cable layout shall be the same as in the validation procedure
2): Ferrite clamp under consideration
Figure 4 - Typical test set-up for table top equipment within the test volume of a FAR

R210-010: 2002 - 14 -
Test volume
X
80 cm
EUT
box
X
1)
1)
EUT
X
cabling
80 cm
Pallet
12 cm
d
Ferrite
A
clamp 3)
A:
turntable and EUT-support
2X: 1,5 m; 2,5 m , 5 m
d: 3 m; 5 m or 10 m
Pallet of 12cm ( 10cm to 14cm ) is a compromise between metal- and wooden ground ( see CISPR 22 subclause 9.1.2 )
1): The antenna cable layout shall be the same as in the validation procedure
2): The cable layout depends on the location of the cable outlets and shall be close to the surface of the housing
3) Ferrite clamp under consideration
Figure 5 - Typical test set-up for floor standing equipment within the test volume of a FAR
6.3 Cable layout and termination
In EMC testing the reproducibility of measurement results is often poor owing to differences in cable
layout and termination, when one single EUT is measured at various Test-Sites.
The following listed items are general conditions of the test set up in order to provide good
reproducibility (see Figure 4 and Figure 5). Ideally all radiation to be measured should only be emitted
from the evaluated test volume. The cables used during the test shall be in accordance with
manufacturers' specifications. If such specifications are not available, the specifications of the used
cables used during testing shall be clearly described in the test report. Also Annex H can serve as a
reference.
1) The cables, that are connected to the EUT and auxiliary equipment or power supply, shall be
arranged with a length of 0,8 m horizontally and 0,8 m vertically (without any bundling) inside
the test volume. Floor standing EUT shall be arranged in the same manner (cable outlet of the
EUT at 80 cm height, as shown in Figure 5). If the manufacturer specifies a shorter length than
1,6 m, then this full length shall be oriented in horizontal and/or vertical direction within the test
volume.
2) Cables, that are not exercised through auxiliary equipment during the test must be
appropriately terminated:
i) Coaxial (shielded) cables with coaxial terminator with correct impedance (50 � or 75 �);
ii) Shielded cables with more than one inner wire must have common mode (line to
reference earth/ground) and differential-mode (line to line) termination in accordance with
EUT manufacturers' specifications.

- 15 - R210-010: 2002
iii) Unshielded cables must have differential mode termination in accordance with
manufacturers' specifications.
3) If the EUT needs auxiliary equipment to be operated properly, special care has to be taken that
no emission of that equipment can influence the radiation measurement. Preferably, auxiliary
equipment should be operated outside the Fully Anechoic Room. The measures against
RF-leakage into the FAR through the interconnection cables must be taken.
The test set up including cable layout, specifications of attached cables and termination, ferrite clamps
and other measures taken to suppress emission outside the test volume must be clearly described in
the test report.
Due to the large variety of EUTs a generally valid definition of the cable layout cannot be given in this
technical report. Corresponding product standards may require special set up conditions.
7 Test procedure
The test set up, EUT and cable layout and termination shall be in accordance with 6.3.
The EUT shall operate within its intended climatic conditions.
The temperature and relative humidity shall be recorded in the test report.
The normal mode(s) of operation of the EUT shall be used. If necessary all of the modes of operation
shall be examined to record the highest amount of disturbance. All units of the EUT capable of
generating disturbances shall be operating in the mode that gives that highest amount of disturbance.
During the measurement the EUT shall be rotated to find the direction of the maximum field strength.
The direction may vary for different frequencies. Measurements shall be made with both vertically and
horizontally polarised antennas.
The need for measurements at one or more heights at frequencies above 400 MHz for products
exceeding 0,5 m in height should be investigated.
If the reading fluctuates the value shall be observed for at least 15 s at each measured frequency. The
highest reading shall be recorded with the exception of any brief isolated clicks (high reading) that
shall be ignored.
8 Test plan
It is a recommended practice that EMC tests are performed according to an EMC test plan provided by
the laboratory and/or the customer and agreed upon by both parties. Guidance is given in
ISO/IEC 17025.
An EMC test plan is a document setting out the specific practices, resources and sequences of activity
relevant to a particular product, service, contract or project.
The configuration, operation and performance of the EUT and auxiliary equipment is essential
information for planning and carrying out EMC tests. Furthermore, the laboratory's and customer's
responsibilities for operating the EUT shall be established before the tests commence.

R210-010: 2002 - 16 -
An EMC test plan may include the following:
1) EUT description
2) description of peripherals (included in EUT/auxiliary equipment)
3) EUT configuration (hardware and software)
4) EUT operating instructions
5) test sequence
6) the customer's role during the tests
7) criteria for terminating the test.
9 Test report
The following information should be addressed in the test report:
1) environmental conditions in the Room (temperature and humidity)
2) a list of instrumentation used including the Room
3) test distance, position and reference point of antenna
4) a description of the test set up (photo)
5) a description of the EUT, cables (type, length) and auxiliary equipment
6) operating mode(s) of the EUT.

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Annex A
(informative)
Determining the Site Reference
For accurate site validations at distances less than 5 m it is recommended to determine the Site
Reference of the antenna pair (transmit and receive antenna). Therefore, a quasi free space test site
is required. It consists of 2 non-metallic antenna masts which allows the placement of antennas at a
certain height above ground level. Care shall be taken to avoid reflections from the ground. The
height (h) above the ground level of the antennas (centre) shall satisfy Equation A.1:
(A.1)
h � d � 5 3
where d is the antenna separation. This distance shall be equal to the actual distance between the
antennas in the Room. The antennas are operated vertically polarised (horizontal polarisation shall not
be used because of stronger interference with the ground-reflected signal). This setup is called "quasi
free space test site". It ensures good approximations of free space (which can never be realized). A
quasi free space test setup has a transmission loss between a receiving and a transmitting antenna in
accordance with true free space transmission loss within � 1 dB.
Clause 5.13 of CISPR 16-1gives details of the method to evaluate a ground plane site (10 m OATS)
using a pair of calculable dipole antennas. Subclause 5.13.5.3.1 sets a tolerance of � 1 dB for
agreement between the measured transmission loss with the calculated value. The same principles
can be used here.
Care has to be taken that the antenna feed cables do not affect the test result. This is best avoided by
arranging the cable as shown in Figure A.1 and putting ferrite rings around the cable.
ct d cr
transmit receive
antenna
h vertically polarised h
non metallic masts
network analyser
d:
calibration distance
h: height of the antennas above soil
ct, cr: coaxial feed cables for transmit and receive antenna oriented horizontally behind the antenna for at least 5 m each.
Figure A.1 – Free space site reference measurement set up

R210-010: 2002 - 18 -
The quality of the reference setup directly influences the FAR evaluation result.
The site reference (SR) is determined in three steps:
1) The insertion loss (M ) is measured in dB with the cables connected together.
2) The transmission loss (M ) is measured in dB with the cables connected to the antennas and
RS
the required distance d between the antennas.
3) The SR is calculated according to Equation A.2.
(A.2)
SR�d�� M � M �d�
0 RS
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Annex B
(informative)
Limit values
The preferred limits are given in Table B.1:
Table B.1 - Preferred limits
Class B Class B Class A Class A
Measurement Level 1 [dB�V/m] Level 1 [dB�V/m] Level 2 [dB�V/m] Level 2 [dB�V/m]
distance
m
30-230 MHz 230-1000 MHz 30-230 MHz 230-1000 MHz
3 354245 52
5 303740 47
10 25 32 35 42
All levels are in dB�V/m using detectors and bandwidth according to Clause 4.
Limits above 1 GHz are under consideration.
These limits are specified to achieve the same compatibility levels for electromagnetic interference as
class B (level 1) and class A (level 2) in EN 55011 and EN 55022.
The limits are based on the limits in the above standards. The intention is that if a large number of
EUT's is tested according to any of these standards they shall as a group give the same result.
However, for the individual EUT it is unavoidable that the result will differ between measurement
methods. None of the methods should take precedence over the other. If that was the case a new test
method will have a more severe limit to ensure that the EUT will also pass a test according to older
methods.
Measurements on open area test sites have many known problems. The main problem often is the
presence of high level background noise. Testing over a ground plane gives measurement result that
can differ extensively from the normal EUT environment. It is a well known fact that as the frequency is
decreased to 30 MHz a horizontally polarised radiator near the ground will give a very low reading on
an OATS. Problems may be found when testing at a shorter distance in a Fully Anechoic Room, but
the errors are small relative to the OATS problems.
For the reason above the comparison between the methods has to be based on statistics. To find the
proper limits several different analyses can be performed.
Simple recalculation:
A simple way to find a new limit is to recalculate based on the changed geometry. A shorter distance
gives higher field strength but the lack of reflections lowers the readings. A 3 m anechoic Room will
measure 10 dB higher compared to an 10 m OATS but 6 dB lower because of the missing ground
reflection. These figures can be worked out to more precise values but that is not meaningful since the
problem actually is more complicated This method implies that the limits should be raised 5 dB in a
3 m Fully Absorber-Line Room.
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Measurements
A comparison can also be based on measurement. Figure B2 below shows a comparison on a limited
number of EUTs (eight) measured both in a 3 m anechoic ferrite tile Room and on a 10 m OATS. It
can be seen that all readings are higher in the Room but there is not a simple correlation. In this case
the difference between the methods is in the range 0,1 to 11,6 dB. None of the EUTs has any
significant emission above 300 MHz. The mean value is 4,2 dB.
Figure B.1 - Differences in emission measurement results between OATS and FAR
Theoretical analysis of simple radiators
A difference of just under 6 dB is expected in measuring field strengths above a ground plane and in
free space. As illustrated by the geometrical optics model (Figure B.2), two rays impinge on the
receive antenna above a ground plane; namely the one transmitted directly between the transmit and
the receive antenna and the one reflected by the ground plane.

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Receive
Antenna
Transmit
Antenna
hr
ht
� �
groundplane
d
Figure B.2 - Geometrical optics model for OATS measurements
The difference in phase relation of these two rays results in an interference pattern which corresponds
to the function of the height of the receive antenna above the ground. The resulting effect ranges from
obliteration to doubling of the direct ray. Figure B.3 illustrates typical interference patterns via the
height of the receive antenna above a ground plane.
4,0
30 MHz
60 MHz
3,5
125 MHz
250 MHz
3,0
500 MHz
1 000 MHz
2,5
2,0
1,5
1,0
20 30 40 50 60 70 80
Field Attenuation [dB]
Figure B.3 - Field attenuation between two half-wave dipoles above ground plane with fixed
transmit antenna height and variable receive antenna height
The interference pattern depends on the distance between transmit and receive antenna, height of the
transmit antenna above the ground plane, polarisation, frequency and type of antennas.
As there is no reflected ray in free space, it is assumed that no interference patterns exist in a Fully
Anechoic Room.
di ct r
re ay
reflected ray
Height [m]
R210-010: 2002 - 22 -
A real EUT is represented by a number of RF-sources driving different types of transmit antennas as
shown in Figure B.4. The type and position of the radiation source is generally not known.
I2
I1
I3
I4
Figure B.4 - Equivalent circuit diagram of a typical Equipment Under Test (EUT)
The results of the theoretical investigation (Dr. Garn, 'Proposal for a new radiated emission test
th
method using a completely absorber lined Room without a ground plane', 9 Zurich symposium on
EMC) are shown in Figure B.5 for 10 m distance and in Figure B.6 for 3 m distance. These figures
show the difference between the received field strength of a horizontally polarised electrically short
straight wire placed above a ground plane and in free space. The receive antenna is moved between
1 m and 4 m above the ground plane and is fixed in the free space situation. The distance between
the transmit and the receive antenna is the same for both sites.
As an example, Figure B.5 shows that the maximum difference in calculated field strengths above a
ground plane and in free space is up to – 22 dB for an EUT height of 0,2 m. The expected difference is
+ 6 dB based on a simple model. That implies a difference of up to 28 dB difference in calculated field
strength.
The reason for this is the wave propagation on an OATS. In horizontal polarisation, below 100 MHz
the constructive interference of dir
...