CISPR 16-1-4:2007/AMD1:2007

CISPR 16-1-4
Edition 2.0 2007-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES
AMENDMENT 1
AMENDEMENT 1
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 1-4: Radio disturbance and immunity measuring apparatus – Ancillary
equipment – Radiated disturbances
Spécifications des méthodes et des appareils de mesure des perturbations
radioélectriques et de l’immunité aux perturbations radioélectriques –
Partie 1-4: Appareils de mesure des perturbations radioélectriques et de
l’immunité aux perturbations radioélectriques – Matériels auxiliaires –
Perturbations rayonnées
CISPR 16-1-4 A1:2007
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CISPR 16-1-4
Edition 2.0 2007-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES
AMENDMENT 1
AMENDEMENT 1
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 1-4: Radio disturbance and immunity measuring apparatus – Ancillary
equipment – Radiated disturbances

Spécifications des méthodes et des appareils de mesure des perturbations
radioélectriques et de l’immunité aux perturbations radioélectriques –
Partie 1-4: Appareils de mesure des perturbations radioélectriques et de
l’immunité aux perturbations radioélectriques – Matériels auxiliaires –
Perturbations rayonnées
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
S
CODE PRIX
ICS 33.100.10; 33.100.20 ISBN 2-8318-9312-7

– 2 – CISPR 16-1-4 Amend. 1 © IEC:2007

FOREWORD
This amendment has been prepared by subcommittee A of CISPR: Radio-interference

measurements and statistical methods.

The text of this amendment is based on the following documents:

FDIS Report on voting
CISPR/A/750/FDIS CISPR/A/760/RVD

Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the maintenance result date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
_____________
INTRODUCTION
In this amendment, the use of a balanced dipole antenna (the CISPR tuned dipole) as a
physical reference for radiated emission measurements in the frequency range between
30 MHz and 300 MHz is deleted. It is replaced by the requirement that in this frequency range
the quantity to be measured is the electric field strength that can be determined using
different types of antennas, provided that the antenna factor and the associated uncertainty
are known.
This fundamental change of measurand in the frequency range between 30 MHz and 300 MHz
was subject to thorough investigations and discussion within CISPR A, and brings it into line
with the measurand that already applies in the rest of the frequency range 9 kHz to 1 GHz,
and indeed above 1 GHz. The decision for this change has been supported by the results of a
questionnaire. More details on the rationale for the decision to introduce the ‘electric field’
measurand instead of the CISPR reference dipoles can be found in the CISPR Maintenance

Cycle Report CISPR/A/541/MCR.
CISPR/A/541/MCR explains that the need for a CISPR reference dipole no longer exists, due
to improvements in the calibration of antennas used for EMC compliance testing and the
increased implementation of quality systems in test and calibration laboratories in accordance
with ISO 17025. Moreover, Clause 4 of CISPR 16-1-4 covers the frequency range 9 kHz to
1 GHz, yet a reference antenna is only specified in the range 30 MHz to 300 MHz, which
seems to make this frequency range an exception to the general rule.
In other words, most measurements of physical quantities are made with an instrument that is
traceable to national standards. There is no need for measurement of electric field strength in
the frequency range 30 MHz to 300 MHz to deviate from this, especially when application of
such a physical reference antenna may give a greater uncertainty to the intended measurand
than a regular calibrated broadband antenna. Moreover, these days, the CISPR reference
dipole is rarely used in practice because it is impractical from a operational point of view (time
consuming). The new measurand is the field strength as defined by the limit level in dBμV/m

CISPR 16-1-4 Amend. 1 © IEC:2007 – 3 –

and as required by the method of measurement. If various operators follow the same

measurement method, involving calibrated antennas, a high degree of reproducibility is

ensured.
A consequence of using the tuned dipole antenna as a reference is that the antenna

uncertainties in CISPR 16-4-2 require the field strength measured by a broadband antenna to

be referred to the field strength that would have been measured had a tuned dipole been

used. The ramifications would be dependent on the difference in radiation patterns and

mutual coupling of a dipole compared to a broadband antenna (including height dependence

of antenna factor). This practice can actually result in larger EMC measurement uncertainties
than if the field strength were derived from the traceably calibrated broadband antenna. The

relating of the behaviour of the commonly used broadband antenna to the extremely rarely

used tuned dipole in the notes to the uncertainty budget in CISPR 16-4-2, requires specialist
knowledge to understand.
Page 3
CONTENTS
Add, on page 5, to the list of tables the titles of the new figures as follows:
Figure 20 – Schematic of radiation from EUT reaching an LPDA antenna directly and via
ground reflections on a 3 m site, showing the half beamwidth, ϕ, at the reflected ray
Figure 21 – Definition of the reference planes inside the test jig
Figure 22 – Example of a 50 Ω adaptor construction in the vertical flange of the jig
Figure 23 – Example of a matching adaptor with balun or transformer
Figure 24 – Example of a matching adaptor with resistive matching network
Figure 25 – The four configurations for the TRL calibration

Page 15
3 Terms and definitions
3.5
antenna
Replace the existing Note 2 by the following new note:
NOTE 2 This term covers various devices such as the wire antenna, free-space-resonant dipole and hybrid
antenna.
3.8
site attenuation
Replace, on page 17, the existing text with the following:
Site attenuation is defined as the minimum site insertion loss measured between two
polarization-matched antennas located on a test site when one antenna is moved vertically
over a specified height range and the other is set at a fixed height.

– 4 – CISPR 16-1-4 Amend. 1 © IEC:2007

3.9
test antenna
Delete the existing definition 3.9, and replace it with the following new definition of site

insertion loss:
3.9
site insertion loss
the loss between a pair of antennas placed at specified positions on a test site, when a direct

electrical connection between the generator output and receiver input is replaced by

transmitting and receiving antennas placed at the specified positions

3.12
quasi-free space test-site
Replace the existing wording of this definition with the following:
facility for radiated emission measurements, or antenna calibration, that is intended to
achieve free-space conditions. Unwanted reflections from the surroundings are kept to a
minimum in order to satisfy the site acceptance criterion applicable to the radiated emission
measurement or antenna calibration procedure being considered
Add, after definition 3.13, the following new definitions:
3.14
cross-polar response
measure of the rejection by the antenna of the cross-polarised field, when the antenna is
rotated in a uniform electromagnetic field
3.15
hybrid antenna
conventional wire-element log-periodic dipole array (LPDA) antenna with boom lengthened at
the open-circuit end to add one broadband dipole (e.g., biconical or bow-tie), such that the
infinite balun (boom) of the LPDA serves as a voltage source for the broadband dipole.
Typically a common-mode choke is used at this end of the boom to minimize parasitic
(unintended) RF currents on the outer conductor of the coaxial cable flowing into the receiver
3.16
low uncertainty antenna
good quality robust biconical or LPDA antenna, whose antenna factor is reproducible to better
than ±0,5 dB, used for the measurement of E-field strength at a defined point in space
NOTE It is further described in A.2.2.

3.17
semi-anechoic chamber
SAC
shielded enclosure, in which five of the six internal surfaces are lined with radio-frequency-
energy absorbing material (i.e., RF absorber), which absorbs electromagnetic energy in the
frequency range of interest, and the bottom horizontal surface is a conducting ground plane
for use with OATS test set-ups
3.18
common mode absorption device
CMAD
a device that may be applied on cables leaving the test volume in radiated emission
measurements to reduce the compliance uncertainty

CISPR 16-1-4 Amend. 1 © IEC:2007 – 5 –

3.19
insertion loss
the loss arising from the insertion of a device into a transmission line, expressed as the ratio

of voltages immediately before and after the point of insertion of a device under test, before

and after the insertion. It is equal to the inverse of the transmission S-parameter, |1/S |
3.20
reflection coefficient
the ratio of a common quantity to both the reflected and incident travelling waves. Hence, the

voltage reflection coefficient is defined as the ratio of the complex voltage of the reflected

wave to the complex voltage of the incident wave. The voltage reflection coefficient is equal to

the scattering parameter S
3.21
short-open-load-through (SOLT) or through-open-short-match (TOSM) calibration
method
calibration method for a vector network analyser using three known impedance standards –
short, open, and match/load, and a single transmission standard – through. The SOLT method
is widely used, and the necessary calibration kits with 50 Ω characteristic impedance
components are commonly available. A full two-port error model includes six error terms for
each of the forward and reverse directions, for a total of twelve separate error terms, which
requires twelve reference measurements to perform the calibration
3.22
scattering parameters (S-parameters)
a set of four parameters used to describe the properties of a two-port network inserted into a
transmission line
3.23
through-reflect-line (TRL) calibration
calibration method for a vector network analyser using three known impedance standards
“Through”, “Reflect” and “Line” for the internal or external calibration of the VNA. Four
reference measurements are needed for this calibration
3.24
vector network analyser
VNA
a network analyser capable of measuring complex values of the four S-parameters S , S ,
11 12
S , S
21 22
Page 17
4 Antennas for measurement of radiated radio disturbance
Add the following sentence to the beginning of the first paragraph
Antennas of the type that are used for radiated emissions measurements, having been
calibrated, shall be used to measure the field strength, taking into account their radiation
patterns and mutual coupling with their surroundings.
In the second paragraph, replace the first sentence “The antenna shall be substantially plane
polarised.” by “The antenna shall be linearly polarised.”
In the third sentence of the second paragraph, after “above ground” add “or above the
absorber in a FAR”.
– 6 – CISPR 16-1-4 Amend. 1 © IEC:2007

4.1 Accuracy of field-strength measurements

Replace the existing title with the following new title.

4.1 Physical parameter for radiated emissions measurements

Add the following paragraph to the beginning of the subclause:

The physical parameter for radiated emission measurements made against an emission limit

expressed in volts per metre is E-field strength measured at a defined point in space relative
to the position of the equipment under test (EUT). More specifically, for measurements in the
frequency range 30 MHz to 1 000 MHz on an OATS or in a SAC, the measurand is the

maximum field strength as a function of horizontal and vertical polarization and at heights
between 1 m and 4 m, and at a horizontal distance of 10 m from the EUT, while the EUT is
rotated over all angles in the azimuth plane.
4.2.1 Magnetic antenna
Delete the last sentence of the first paragraph of the Note, i.e.: “This assumption is justified….
H level in dB(μA/m).”
Delete also the second paragraph of the Note: “It should be clearly understood that the above
fixed E and H ratio applies only under far-field conditions”.
4.2.2 Balance of antenna
Replace the existing title and text of this subclause with the following:
4.2.2 Shielding of loop antenna
Inadequate shielding of a loop antenna can result in E-field response. The E-field
discrimination of the antenna shall be evaluated by rotating the antenna in a uniform field,
such that the plane of the loop remains parallel to the E-field vector. When the plane of the
loop antenna is perpendicular to the magnetic flux and then the antenna is rotated so that its
plane is parallel to the magnetic flux the measured response shall decrease by at least 20 dB.
4.3.1 Electric antenna
Delete, in the second paragraph, the words “1 m length” and add the following sentence:
“Annex B states that the antenna factor derived by the Equivalent Capacitor Substitution
Method (ECSM) has greater uncertainties for monopole lengths greater than one-eighth of a
wavelength”.
Delete the third paragraph i.e. “Where the distance….10% of the distance”.
4.3.3 Balance of antenna
Replace the existing title with the following new title.
4.3.3 Cross-polar response of antenna
Modify the text as follows:
If a balanced electric field antenna is used, it shall comply with the requirement of 4.4.3. If a
balanced magnetic field antenna is used, it shall comply with the requirement of 4.2.2.”

CISPR 16-1-4 Amend. 1 © IEC:2007 – 7 –

4.4 Frequency range 30 MHz to 300 MHz

Replace the existing title with the following new title.

4.4 Frequency range 30 MHz to 1 000 MHz

After the title of 4.4, add the following text:

In this frequency range the measurements are of the electric field, so magnetic field antennas

are not included. The antenna shall be a dipole-like antenna designed to measure the electric

field. This includes tuned dipole antennas, whose element pairs are either straight rods or

conical in shape, and dipole arrays such as the log-periodic dipole array (LPDA) antenna,
comprising a series of staggered sets of straight rod elements, and hybrid antennas.
4.4.1 Electric antenna
Delete the entire subclause, including 4.4.1, 4.4.1.1, 4.4.1.2 and 4.4.1.3:
Add a new subclause 4.4.1 as follows:
4.4.1 Low-uncertainty antenna for use if there is an alleged non-compliance to the E-
field limit
For lower measurement uncertainty, the value of E-field strength measured by a typical
biconical antenna or LPDA antenna is preferred, in particular over hybrid antennas. Typical
biconical and LPDA antennas are defined in Annex A and only calibrated antennas shall be
used.
NOTE 1 Improved uncertainties are achieved by using the biconical antenna over the frequency range 30 MHz to
250 MHz and the LPDA antenna over the range 250 MHz to 1 GHz. Alternatively, a change-over frequency of
200 MHz can be used, but uncertainties due to phase centre variations of the LPDA will be higher and must be
included in the reported radiated emissions measurement uncertainty budget.
NOTE 2 The measurement uncertainty of radiated emissions from an EUT depends on many different influence
factors such as the quality of the site, antenna factor uncertainty, antenna type, and the measurement receiver
characteristics. The reason for defining low-uncertainty antennas is to limit other antenna influences on the
measurement uncertainty, such as the effect of mutual coupling with a ground plane, the radiation pattern with
respect to height scanning, and the variable phase centre position. Verification of effects of these influences is a
comparison of the readings of the two antennas at the selected change-over frequency, which should give the
same value of E-field strength within a margin of ± 1 dB.
Add the following new subclause 4.4.2:
4.4.2 Antenna characteristics
Since, at the frequencies in the range 300 MHz to 1 000 MHz, the sensitivity of the simple
dipole antenna is low, a more complex antenna may be used. Such antenna shall be as
follows.
a) The antenna shall be linearly polarized, which shall be evaluated by applying the cross-
polarization test procedure of 4.4.4.
b) Balanced dipole antennas, such as tuned-dipole and biconical antennas, shall have
validated balun performance, which shall be evaluated by applying the balance test
procedure of 4.4.3. This also applies to hybrid antennas below 200 MHz.
c) A test site with a conducting ground plane is assumed. The amplitude of the received
signal will be reduced if either or both the direct and ground reflected signals from the
EUT to the antenna are not entering the mainlobe of the radiation pattern of the antenna
at its peak. The peak is usually in the boresight direction of the antenna. This reduction in
amplitude is taken to be an error in the radiated emission: the ensuing uncertainty
tolerance is based on the beamwidth, 2ϕ, see Figure 20.

– 8 – CISPR 16-1-4 Amend. 1 © IEC:2007

ϕ
h
h
d
IEC  1772/07
Figure 20 – Schematic of radiation from EUT reaching an LPDA antenna directly and via
ϕ, at the reflected ray
ground reflections on a 3 m site, showing the half beamwidth,

Conditions for ensuring that this error is no larger than +1dB are given below in 1) for a
10 m site and 2) for a 3 m site. Alternatively a condition based on antenna gain is given in
3) in order to bypass the laborious radiation pattern conditions.
Emission measurements are performed with the antenna horizontally and vertically
polarised. If it is chosen to measure the radiation patterns in only one plane, the narrower
patterns shall be used, as follows: the pattern of the antenna shall be verified in the
horizontal plane while orienting it for horizontal polarisation.
1) For a 10 m OATS or SAC the antenna response in the direction of the direct ray differs
negligibly from the boresight amplitude when the antenna is aligned such that its
boresight direction is parallel to the ground plane. The directivity component of the
uncertainty in the emission measurement can be kept to less than + 1 dB if the
antenna response in the direction of the reflected ray is no more than 2 dB lower than
the antenna boresight response. To ensure this condition, the total vertical beamwidth
2ϕ of the measurement antenna, within which the antenna gain is within 2 dB of its
maximum, shall be such that:
–1
ϕ > tan [(h + h )/d]
1 2
2) For sites with less than 10 m separation, typically 3 m, the total vertical beamwidth 2ϕ
of the measurement antenna, within which the antenna gain is within 1 dB of its
maximum, shall be such that:
–1 –1
2ϕ > tan [(h + h )/d] – tan [(h – h )/d]
1 2 1 2
where:
h is the height of the equipment under test;
h is the measurement antenna height;
d is the horizontal distance between the phase centre of the measurement antenna
and the device under test.
CISPR 16-1-4 Amend. 1 © IEC:2007 – 9 –

If antenna down tilting that would reduce the associated uncertainties is not employed,

the reduction in received signal shall be calculated, see Note, from the radiation

patterns and applied as corrections or as directivity uncertainties. Example

uncertainties budgets are given in CISPR 16-4-2.

NOTE 1 Assuming an E-field radiation pattern normalised to unity on boresight (= peak of mainlobe)

read the E-field at the angles of declination from the antenna for the direct, E , and reflected rays, E .
D R
The error, compared to an E-field of unity magnitude for each of the direct and reflected rays, is given

in decibels by: 20log (2/(E + E )).
D R
NOTE 2 The reduction in signal strength caused by reduced directivity at angles off antenna

boresight is a systematic error and therefore can be corrected. If a correction is applied, from

knowledge of the radiation patterns at each frequency and polarisation, the uncertainty in emitted
signal strength can be reduced accordingly.

3) For broad beamwidth antenna types used for radiated emission testing, such as
biconical, LPDA and hybrid antennas, the beamwidth is inversely related to
antenna directivity. An alternative to the criterion based on beamwidths in 1) and 2)
above, is to specify the maximum gain of an antenna and to refer to generic
uncertainty tolerances for the directivity component in the uncertainty budget for an
emission test. The generic uncertainties, based on the narrowest beamwidths in
the frequency range used for a given antenna, are given in CISPR 16-4-2. The
maximum isotropic antenna gain for biconical antennas shall be 2 dB, and shall be
8 dB for log-periodic dipole array (LPDA) and hybrid antennas. For V-type LPDA
antennas, whose H-plane beamwidth is equalised to the E-plane beamwidth, the
maximum permissible isotropic gain shall be 9 dB.
NOTE 3 The directivity uncertainties given in CISPR 16-4-2 (2004) can be used for a 10 m separation,
but revised uncertainties are needed for a 3 m separation.
d) The return loss of the antenna with the antenna feeder connected shall not be less than
10 dB. A matching attenuator may be part of the feeder cable for antennas if needed to
meet this requirement.
e) A calibration factor shall be given making it possible to fulfil the requirements of 4.1.
Renumber existing subclause 4.4.2 as subclause 4.4.3 and all of its subclauses accordingly.
4.4.2.1 Introduction (renumbered 4.4.3.1))
Delete the third paragraph: “This subclause considers the balun contribution. Contribution a)
is under consideration (see last sentence of Note 1 of 4.4.2.2).”
Renumber existing subclause 4.4.3 as subclause 4.4.4.
In the title of the renumbered subclause 4.4.4, replace the word “performance” with the word
“response”
Delete existing subclause 4.5.
Renumber existing subclause 4.6 as subclause 4.5.
4.6 Frequency range 1 GHz to 18 GHz (renumbered 4.5)
Replace the second sentence of renumbered subclause 4.5 with: “Examples are LPDA
antennas, double-ridged guide horns and standard gain horns.”
Delete the note.
Renumber subclause 4.7 as subclause 4.6 and subclause 4.7.1 accordingly.

– 10 – CISPR 16-1-4 Amend. 1 © IEC:2007

Page 47
5.7.1 Normalized site attenuation for alternative test sites

In the first sentence of the fourth paragraph, replace “… less than 1 m …” by “…at least 1

m …”.
Page 51
Replace the existing Figures 6a and 6b with the following:

Receive Transmit
antenna antenna
d
d
d
d
d
Antenna to be relocated
Test
to maintain constant
volume
distance d
IEC  1770/07
Figure 6a – Typical antenna positions for alternative test site –
Vertical polarization NSA measurements

Receive Transmit
antenna
antenna
d
d
d
d
d
Antenna to be relocated
Test
to maintain constant
volume
distance d
IEC  1771/07
Figure 6b – Typical antenna positions for alternative test site –
Horizontal polarization NSA measurements

CISPR 16-1-4 Amend. 1 © IEC:2007 – 11 –

Page 113
Add a new Clause 9 as follows.

9 Common mode absorption devices

9.1 General
Common mode absorption devices (CMADs) are applied on cables leaving the test volume
during a radiated emission measurement. CMADs are used in radiated emission

measurements to reduce variations in the measurement results between different test sites,

due to possible differing values of common mode impedance and symmetry at the point where
cables leave the test site (e.g. turntable centre). The basic characteristics of CMADs can be
expressed in terms of S-parameters. Derived performance quantities such as insertion loss or
reflection coefficient can be determined from these S-parameters. This clause specifies the
measurement method for the verification of the S-parameters of a CMAD.
9.2 CMAD S-parameter measurements
S-parameters measured in a test jig, as described in 9.3, are used to characterise the
properties of a CMAD. The values of the complex S-parameters are evaluated at the
reference planes indicated in Figure 21. The reference method for the measurement of S-
parameters with the highest possible accuracy uses a vector network analyser (VNA) and the
TRL calibration method, as described in 9.4.
9.3 CMAD test jig
A test jig used for measuring the S-parameters of a CMAD under test shall have a cylindrical
metal rod above a metal ground plane, as shown in Figure 21. The metal rod between the
vertical flanges of the test jig consists of three sections: one section forming a transmission
line in the jig between the two reference planes, and two adaptor sections between the
reference planes and the adaptor ports.
The effects on the measurement of a CMAD from the adaptor sections and the adaptor ports
can be eliminated by using the TRL calibration method described in 9.4, providing a low
uncertainty for the final measurements. Any type of adaptor may be used for the
measurements of 9.4. Examples of adaptors are shown in Figures 22 to 24.
The diameter d of the cylindrical rod shall be 4 mm. The height above the ground plane, h, is
defined by the dimensions of the CMAD. Typical values are 30 mm, 65 mm, and 90 mm. The
measurement shall be performed at the height defined by the construction of the CMAD. The
,
distance between the reference plane and the vertical flange of the jig (adaptor section), L
A
shall be at least 2 h (see Figure 21). The distances between the reference planes and the
CMAD ends, D and D , should be as small as possible, but not larger than h. The metal
A B
ground plane of the test jig shall be greater than (L + 4 h) in length and greater than 4 h in
jig
width.
, is given by the internal diameter of the line, d, (defined to
The characteristic impedance, Z
ref
be 4 mm), and by the height of the centre of the rod above the ground plane, h:
Z
⎛ 2h⎞
0 −1
Z = cosh ⎜ ⎟ in Ω (17)
ref
2π d
⎝ ⎠
where
Z is the free-space impedance (120 π) in Ω;
d is the test conductor diameter (defined to be 4 mm);

– 12 – CISPR 16-1-4 Amend. 1 © IEC:2007

h is the height of the centre of the test conductor above the ground plane.

EXAMPLE Typical values of Z for various heights h are:

ref
h = 30 mm >> Z = 204 Ω
ref
h = 65 mm >> Z = 248 Ω
ref
h = 90 mm >> Z = 270 Ω
ref
9.4 Measurement method using the TRL calibration

The TRL calibration method is recommended for measuring the S-parameters of CMADs. Use
of this calibration procedure allows selection of the reference plane inside the test jig such
that it is in close proximity to the location where the CMAD under test will be placed and
hence distances D and D can be minimized (see Figure 21). The calibration requires a
A B
metal rod (termed “line”) with the same diameter and height as the transmission line section
of the jig. The characteristic impedance and length of the line section have to be known
exactly, and are introduced into the calibration data used by the firmware of the VNA or by
external correction calculations.
The length of the line section, used for a TRL calibration process, determines the frequency
range in which the TRL calibration can be performed. This frequency limitation results from
the mathematical procedure used in the TRL calibration method, where at some frequencies a
divide-by-zero (or very small values) condition is possible and must be avoided.
If the length of the “line” reference is L, the frequency range shall be limited to between low
and high frequencies f and f as follows:
L H
c
f = 0,05 (18)
L
L
c
f = 0,45 (19)
H
L
where c is 3x10 m/s. A “line” length of 0,6 m is appropriate for calibration in the frequency
range 30 MHz to 200 MHz. If the measurement has to be extended to higher frequencies, a
second “Line” calibration is necessary. A second calibration with a “Line” length of 0,12 m
would be appropriate for the frequency range 150 MHz to 1 000 MHz.
Four calibration configurations are necessary for the TRL calibration method:

a) “Reflect” (Port A): Measuring the complex value S of the adaptor section and adaptor at
port 1 without any other connection (simulating an open-circuit condition) [Figure 25 a)]
b) “Reflect” (Port B): Measuring the complex value S of the adaptor section and adaptor at
port 2 without any other connection (simulating an open-circuit condition) [Figure 25 b)]
c) “Through”: Measuring the complex values S , S , S , S with the two adaptor sections
11 12 21 22
directly connected together (without the line section in between) [Figure 25 c)]
d) “Line”: Measuring the complex values S , S , S , S with the line section introduced
11 12 21 22
[Figure 25 d)]
These calibration measurements yield 10 complex numbers for each frequency point. If the
VNA includes a firmware for TRL calibration, it will use these reference measurements to
calculate the proper corrections for the TRL measurement. If the VNA does not support the
TRL calibration, the necessary corrections may be made independent of the VNA according to
the procedure described in CISPR 16-3.

CISPR 16-1-4 Amend. 1 © IEC:2007 – 13 –

The properties of the adaptor sections and adaptor ports outside of the calibration planes do

not need to be known for the TRL calibration – these are measured in the calibration

procedure and are compensated correctly by the TRL calibration. Different types of adaptors

may be used. It is recommended to use the same type of adaptors and the same length of the

adaptor section on both ends of the test jig. It is also recommended that the two adaptor

sections are the same length, i.e. that L = L .
A B
After calibration, the CMAD under test is introduced into the line section of the test jig. The

adaptor sections and adaptors have to be exactly the same as used for the calibration. The

length of the metal rod can be different from the length of the “line” used for the calibration,

but the diameter (4 mm) and the height above the ground plane shall be the same as used for

the calibration. The metal rod inside the CMAD should be positioned as accurately as possible
in the centre of the CMAD opening. The length of the metal rod can be selected such that the
reference plane corresponds with the physical ends of the CMAD (i.e. D as small as
A
possible). Typical CMADs have a length of 0,6 m. In this case, the 4 mm line section can be
used for calibration covering the frequency range of 30 MHz to 200 MHz, as well as for the
measurement of the CMAD (also including the frequency range above 200 MHz, calibrated by
a shorter line section). The measurement results for a CMAD under test using the VNA
measurement corrected by the TRL calibration is a set of the four S-parameters referenced to
the characteristic impedance of the transmission line section (empty jig), Z .
0_jig
9.5 CMAD performance (degradation) check using spectrum analyser (SA) and
tracking generator (TG)
The complex S-parameters of a CMAD cannot be measured without using a VNA. However,
VNA instruments may not be available in all EMC test laboratories. For laboratories that do
not have access to VNA instruments, a simpler method to check the functioning of a CMAD is
defined in this subclause, using a spectrum analyser with tracking generator. This
instrumentation set-up measures only the magnitude of the insertion loss, but this measured
value will not be directly related to the S-parameters measured at the reference planes shown
in Figure 21. Nonetheless, an EMC laboratory can periodically repeat the same insertion loss
measurement with their in-house test set-up, using the exact same conditions (impedance and
geometry of the test set-up), and record and compare the history of the results to decide
whether the CMAD is still in acceptable condition. Degradation of CMAD performance can be
detected in this way. If some degradation becomes apparent, a reference measurement shall
be performed using a VNA with the TRL calibration method of 9.4.
Any adaptor construction (Figures 22 to 24) can be used for this performance/degradation
check. To avoid resonance effects in cables between test jig and measurement instrument, it
is necessary to include two 10 dB attenuators close to the test jig connection during this
performance check.
When 50 Ω adaptors are used (Figure 22), the insertion loss measurement for the
performance/degradation check is the difference in dB between attenuation measurements for
the following two configurations:
a) Configuration 1: direct connection of the two attenuators without the test jig.
b) Configuration 2: the two attenuators connected to the test jig with the CMAD included.
If matching adaptors (Figure 23 or Figure 24) are used, the insertion loss measurement for
the degradation check is the difference between the attenuation measured for the following
two configurations:
a) Configuration 1: the two attenuators connected to the test jig without the CMAD (empty jig);
b) Configuration 2: the two attenuators connected to the test jig with the CMAD included.

– 14 – CISPR 16-1-4 Amend. 1 © IEC:2007

Reference planes
selected close to the
mechanical end of the
CMAD under test
Adaptor
Adaptor
section B
section A
Line section of the jig
of the jig
of the jig
Adaptor
Adaptor
port A
port B
(including the
(including the
jig flange and D
L > 2h jig flange and
A A
D
B L > 2h
CMAD under test B
adaptor section)
adaptor section)
h
Ground plane of the test jig
Height h above ground plane
Metal rod of 4 mm in diameter
adapted to the CMAD construction
as test conductor
(typical values: 30 mm, 65 mm, 90 mm)
IEC  1773/07
Figure 21 – Definition of the reference planes inside the test jig
Dimensions in mm
Metal
Line elements
(metal rod of 4 mm diameter)
of different lengths for the calibration
and measurement with banana Teflon
connector at the end for connection in
the test jig
N-connector
19,5 6
Height h above ground plane
depending on the CMAD
construction
IEC  1774/07
The bottom sides of the vertical flange have to be electrically bonded to the metallic ground plane

Figure 22 – Example of a 50 Ω adaptor construction in the vertical flange of the jig

CISPR 16-1-4 Amend. 1 © IEC:2007 – 15 –

MMetetaall f fllaangenge
MeMetatal cl caasese
DDiielelececttrriicc sp spacacerer,,
didiaammeteteerr > > 15 15 mmmm
NN--coconnnnececttoorr
4 m4 mmm
200 Ω : 50 Ω
202000Ω Ω : 5: 500ΩΩ
h hh
BBalunalun or t or trranansfsforormmeerr
20200 0 ΩΩ : 5: 500 ΩΩ
IEC  1775/07
If the centre tap of the balanced port is connected to the balun case, it must be disconnected.
Figure 23 – Example of a matching adaptor with balun or transformer

Z
0 _ jig
R = 50 Ω
Z − 50
0 _ jig
R = Z (Z − 50) Ω
2 0_jig 0_jig
R
N-connector
R1
h Z R R
0_jig 1 2
mm
Ω Ω Ω
30 204 57,6 177,3
65 248 56,0 221,6
90 270 55,4 243,7
IEC  1776/07
Figure 24 – Example of a matching adaptor with resistive matching network

– 16 – CISPR 16-1-4 Amend. 1 © IEC:2007

Reference
plane
50 Ω
IEC  1777/07
a) Configuration for the calibration measurement “reflect port A”

Reference
plane
50 Ω
IEC  1778/07
b) Configuration for the calibration measurement “reflect port B”
Reference
plane
50 Ω
50 Ω
c) Configuration for the calibration measurement “through” IEC  1779/07
Reference
Reference
plane
plane
Line section
50 Ω
Reference line length L
50 Ω
IEC  1780/07
d) Configuration for the calibration measurement “line”

NOTE The length L of the reference line for the calibration needs not to be the same as the length used for the
measurement of the CMAD. The length of the reference line for the calibration procedure has to be selected

according to the frequency range needed.

Figure 25 – The four configurations for the TRL calibration

Page 115
Annex A (normative) Parameters of broadband antennas
Amend the existing title as follows:
Annex A (normative) Parameters of antennas

CISPR 16-1-4 Amend. 1 © IEC:2007 – 17 –

A.1 Introduction
Replace the existing text by the following:

Various CISPR publications specify particular antennas to be used in making measurements.

Other types of antennas can be used provided the results are equivalent to those obtained

with the specified antenna. The comparison of these antennas to the specified antennas will

be aided by listing appropriate parameters. These parameters shall be specified as part of

any CISPR acceptance of a new antenna type. Antenna manufacturers shall also use this

information as guidance in specifying the most useful aspects of antennas used for radiated

emissions measurements. Manufacturers are recommended to supply generic information on

each antenna model including the following parameters: free-space antenna factor into a 50 Ω
system, return loss, radiation patterns at sufficient frequency intervals to indicate significant
changes (which include beamwidth information), and frequency dependent uncertainty values
to account for the deviation from free-space antenna factor caused by mutual coupling to a
ground plane when the antenna is scanned in height between 1 m and 4 m.
Insert the following new Clauses A.2 and A.3.
A.2 Preferred antennas
If there is an alleged non-compliance to the E-field limit, the value measured by a low-
uncertainty antenna is preferred. A low-uncertainty antenna is one with which the field
strength on a CISPR test set-up can be measured with a lower uncertainty than is required for
other antennas that meets the field strength accuracy criterion of 4.1. The low-uncertainty
antennas are described in A.2.2.
A.2.1 Calculable antenna
The calculable standard dipole antenna achieves the lowest uncertainty for E-field strength.
The antenna factor can be calculated for free-space and at any height and polarisation above
a well-defined ground plane. The principle of the calculable standard dipole is described in
CISPR 16-1-5, in which only the resonant condition is described. However using widely
available numerical electromagnetic modelling the antenna factor for a single dipole length
can be calculated over
...