CISPR 16-1-6:2014/AMD2:2022
(Amendment)Amendment 2 - Specification for radio disturbance and immunity measuring apparatus and methods - Part 1-6: Radio disturbance and immunity measuring apparatus - EMC antenna calibration
Amendment 2 - Specification for radio disturbance and immunity measuring apparatus and methods - Part 1-6: Radio disturbance and immunity measuring apparatus - EMC antenna calibration
Specifies a procedure for the determination of the kinematic viscosity of mineral insulating oils, both transparent and opaque, at very low temperatures, after a cold soaking period of at least 20 h, by measuring the time for a volume of liquid to flow under gravity throught a calibrated glass capillary viscometer. Applies at all temperatures to both Newtonian and non-Newtonian liquids having viscosities of up to 20 000 mm2/s.
Amendement 2 - Spécification des méthodes et des appareils de mesure des perturbations radioélectriques et de l'immunité aux perturbations radioélectriques - Partie 1-6: Appareils de mesure des perturbations radioélectriques et de l'immunité aux perturbations radioélectriques - Étalonnage des antennes CEM
Spécifie un mode opératoire pour la détermination de la viscosité cinématique des huiles minérales isolantes, transparentes ou opaques, à très basse température, après une période de repos d'au moins 20 h, en mesurant le temps nécessaire à un volume de liquide pour qu'il s'écoule par gravité à travers un viscosimètre à capillaire en verre étalonné. S'applique à toutes les températures aux liquides newtoniens ou non-newtoniens ayant une viscosité inférieure ou égale à 20 000 mm2/s.
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CISPR 16-1-6 ®
Edition 1.0 2022-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
AMENDMENT 2
AMENDEMENT 2
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 1-6: Radio disturbance and immunity measuring apparatus – EMC antenna
calibration
Spécification des méthodes et des appareils de mesure des perturbations
radioélectriques et de l’immunité aux perturbations radioélectriques –
Partie 1-6: Appareils de mesure des perturbations radioélectriques et de
l'immunité aux perturbations radioélectriques – Étalonnage des antennes CEM
CISPR 16-1-6:2014-12/AMD2:2022-03 (en-fr)
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CISPR 16-1-6 ®
Edition 1.0 2022-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
AMENDMENT 2
AMENDEMENT 2
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 1-6: Radio disturbance and immunity measuring apparatus – EMC antenna
calibration
Spécification des méthodes et des appareils de mesure des perturbations
radioélectriques et de l’immunité aux perturbations radioélectriques –
Partie 1-6: Appareils de mesure des perturbations radioélectriques et de
l'immunité aux perturbations radioélectriques – Étalonnage des antennes CEM
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.10; 33.100.20 ISBN 978-2-8322-1075-2
– 2 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SPECIFICATION FOR RADIO DISTURBANCE AND
IMMUNITY MEASURING APPARATUS AND METHODS –
Part 1-6: Radio disturbance and immunity measuring apparatus –
EMC antenna calibration
AMENDMENT 2
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
Amendment 2 to CISPR 16-1-6:2014 has been prepared by subcommittee CISPR A: Radio-
interference measurements and statistical methods, of IEC technical committee CISPR:
International special committee on radio interference.
The text of this Amendment is based on the following documents:
Draft Report on voting
CIS/A/1362/FDIS CIS/A/1365/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Amendment is English.
© IEC 2022
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications/.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.
_____________
– 4 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
2 Normative references
Add to the existing list the following new references:
CISPR 16-1-2, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1-2: Radio disturbance and immunity measuring apparatus – Coupling devices
for conducted disturbance measurements
CISPR 16-1-4:2019, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1-4: Radio disturbance and immunity measuring apparatus – Antennas and test
sites for radiated disturbance measurements
3.1.2.5
magnetic field antenna factor
Replace the existing Note 1 to entry and Note 2 to entry as follows:
Note 1 to entry: The symbol F is used only when antenna factor is expressed in dB. The quantity F is expressed
aH aH
−1 −1
in dB(S/m) or dB(Ω m ).
Note 2 to entry: The unit dB(pT/µV) is used in some standards (but not in CISPR 16-1-6), which can be converted
to dB(S/m) by subtracting 2 dB.
Add Note 3 to entry:
Note 3 to entry: CISPR 16-1-4 specifies loop antennas for magnetic field strength measurements in the frequency
range of 9 kHz to 30 MHz.
3.2 Abbreviations
Add to the existing list the following new abbreviations:
CPM current probe method
SFM standard field method
5.2.1 General
Replace the second and third paragraphs by the following five new paragraphs:
Several techniques have been developed for calibrating loop antennas or measuring magnetic
field antenna factors [74]. Reference [18] provides a useful overview. Reference [15] provides
a simplified version of the standard field method (SFM) ([32] and [16]), and the TAM is described
in [35]. This subclause and Annex H specify acceptable calibration methods for loop antennas.
The TAM and the TEM cell method yield a standard uncertainty of measured antenna factor of
approximately ± 0,5 dB, while application of the TEM cell method is restricted to the frequency
range below the first resonant frequency of the TEM cell.
The current probe method (CPM) [15] is an improved SFM based on IEEE Std 291 [32]. In the
original method, the current flowing in the transmit loop antenna was measured using an RF
vacuum thermocouple built into the loop element; however, a thermocouple is typically small
and fragile, and therefore is not suitable for use in routine calibration measurements.
© IEC 2022
The Helmholtz coil method [34], categorized as a SFM, is accurate to 0,7 % (0,06 dB) up to
150 kHz, and better than ± 0,5 dB up to 10 MHz (see Annex H), but its applicable frequency
range depends on the coil size.
A sufficient signal-to-{receiver noise} ratio of at least 34 dB is necessary to obtain low
measurement uncertainties, if using a VNA as described in 6.2.4. In addition, it is important to
attach attenuators to the transmit loop antenna and the receive loop antenna, to reduce
mismatch uncertainties if using a signal generator and a receiver. When calibrating a loop
antenna in free-space conditions, the distance between the transmit antenna or the receive
antenna and any nearby reflecting objects, including any metallic ground plane, should be
greater than 1,3 m; the clearance required also depends on the spacing between the antennas.
Add, at the end of the existing 5.2.2.2, the following new subclauses:
5.2.3 Three antenna method (TAM)
5.2.3.1 General
Antenna calibration using the TAM requires three antennas (numbered as 1, 2, and 3) to form
three antenna pairs. Prior knowledge of the AF of any of the three antennas is not needed with
the TAM (see also 4.3.3 about the TAM).
SIL for antenna calibration is usually measured with a calibrated network analyzer, to reduce
mismatch errors that may occur between the signal output port and the transmit loop antenna,
as well as between the signal receiving port and the receive loop antenna. Alternatively, a
combination of signal/tracking-generator and measuring receiver can be used; in this case,
padding attenuators are required to reduce standing waves on the cables.
Different from TAM calibrations above 30 MHz, which are based on the Friis transmission
equation, the TAM method for loop antenna calibrations is based on a modified Neumann
mutual inductance formula [75], which is approximately expressed by the so-called Greene’s
formula [70].
The separation distance between the transmit antenna and the receive antenna shall be small
compared to the distance to the surroundings. Therefore, coupling between the antennas is
maximized, while coupling to the surroundings is minimized. A specific site validation criterion
is not required, but the influences from the site on the magnetic field antenna factor results shall
be estimated; see the discussion in 5.2.3.2.
5.2.3.2 Calibration procedure
(i,j),
For antenna pairs coaxially aligned as shown in Figure 21, the site insertion loss, A
i
between antenna i and antenna j is measured in a free-space environment [35], and is described
by Equation (61).
A(i, j)= F (i)+ F ( j)+ 45,9+ 20lg( f )− 20lg[K(i, j)] (61)
in dB
i aH aH MHz
From data on the A (i,j) for the three antenna pairs, the magnetic field antenna factors F of
i aH
each antenna can be determined using Equations (62).
– 6 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
F (1)= [− 45,9− 20lg f + A(1,2)+ A(1,3)− A(2,3)+ K(1,2)+ K(1,3)− K(2,3)]
aH MHz i i i
F (2)= [− 45,9− 20lg f + A(1,2)− A(1,3)+ A(2,3)+ K(1,2)− K(1,3)+ K(2,3)] in dB(S/m)
(62)
aH MHz i i i
[ ]
F (3)= − 45,9− 20lg f − A(1,2)+ A(1,3)+ A(2,3)− K(1,2)+ K(1,3)+ K(2,3)
aH MHz i i i
where
f is the frequency in MHz;
MHz
A (i,j) is the SIL between antenna i and antenna j; when it is measured using a network
i
analyzer, the site insertion loss is given by Equation (63).
A(i, j)=−20lg S (i, j) in dB;
(63)
i 21
K(i,j) is the function shown in Equation (64), based on a modified Neumann equation for
antenna pair (i,j)
− jβ R
1 e
−3
K ij, 20lg dss⋅ d in dB(m )
( ) (64)
i j
∫∫
CC
4πSS R
ji
ij
and
2 2
S ,S are the geometric areas (r π) in m of antennas i and j, respectively;
i j
C ,C are the closed curves encircling the loop element of antennas i and j, respectively;
i j
ds ,ds are infinitesimal segment vectors of the loop elements of antennas i and j, respectively;
i j
R is the distance in m between the segments ds and ds .
i j
If the three loop antennas are true circles and a homogeneous current distribution along each
loop is assumed, Equation (64) can be expressed approximately by the following form:
2 4
2 2
1+β R (i, j) r r r r
15 315
i j i j
−3
K(i, j) 20lg 1 in dB(m )
= + + (65)
3 2 2
8 64
2π R (i, j) R (i, j) R (i, j)
0 0 0
=
© IEC 2022
Equation (65) is called Greene’s formula [70], where
(66)
2 2 2
R (i, j)= d + r + r in m
0 ij i j
r ,r are the radii in m of antennas i and j, respectively;
i j
d is the distance, in m, between the loop centres of antennas i and j;
ij
−1
β is the wave number (=2π/λ) in m .
Equation (65) is valid under the conditions that βR (i, j)≤ 1,0 and r r R (i, j)≤ 1 16 . Equation (64)
0 i j 0
and Equation (65) can be fulfilled if the current distribution on both loop antennas is uniform.
To calibrate loop antennas accurately, the radius of the loop antenna driven as the transmit
loop shall be within derived limits; for example, Table 15 shows suitable combinations for r , r ,
i j
and d , and indicates the error of Greene’s formula at the highest frequency of 30 MHz. The
ij
frequency dependency of the error is shown in Figure 22. The loop centre distance between a
pair of antennas, d , should be selected to fulfil the conditions, and shall be as small as possible
ij
to minimize influences from the surroundings. It should be noted that other uncertainty terms,
such as the positioning uncertainty increase as the separation reduces.
An estimate for the influence of a ground plane with different loop separation distances d
ij
ranging from 0,1 m to 1,0 m is given in Figure 23. Figure 23 is obtained by normalizing the SILs
between two loop antennas with 60 cm diameter placed 1,3 m and 2,5 m above a ground plane
to the SILs in free space. An OATS or a SAC can be used as the calibration test site, and the
particular influence of the calibration test site shall be taken into consideration for the calibration
measurement uncertainty estimation. The influence of the ground plane also depends on the
position of the feed gaps of the two loop antennas.
Alternatively to Equations (62), Equations (67) can be used, which are based on a numerical
simulation approach. The advantage of the numerical simulation approach is that the
inhomogeneous current distribution is taken into account. The conditions required for the
application of Greene’s formula do not apply for the numerical simulation approach. It is not
necessary to take into account the error given in Table 15.
F 1 AAA1,2+ 1,3− 2,3− A 1,2− A 1,3+ A 2,3
() ( ) ( ) ( ) ( ) ( ) ( )
aH iii N N N
in dB(S/m) (67)
F (2) A(1,2)−+A(1,3) A(2,3)− A (1,2)+ A (1,3)− A (2,3)
aH i i i NNN
F 3=−AA1,2+ 1,3+ A 2,3+ A 1,2− A 1,3− A 2,3
( ) ( ) ( ) ( ) ( ) ( ) ( )
aH i i i N N N
where
A (i,j) is the SIL between antenna i and antenna j; when it is measured using a network
i
analyzer, the site insertion loss is given by Equation (63).
=
=
– 8 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
A (i,j) is the normalized site insertion loss (NSIL) calculated by NEC. The same loop
N
geometry shall be used for simulation and calibration. Further information about
normalized site attenuation calculation is planned for inclusion in future editions of
CISPR 16-1-4.
Greene’s formula does not apply if the antennas do not have circular shapes. For square shapes,
it is feasible to modify Equation (65) by a correction factor for r or r where
i j
(68)
r= 1,13(s 2) and r = 1,13(s 2)
i i j j
r r are the radii, in m, of antennas i and j, respectively;
i, j
s ,s are the side lengths, in m, of the square loops i and j, respectively.
i j
To obtain K(i,j) for square shapes accurately, or to obtain K(i,j) for other loop antenna shapes,
K(i,j) should be calculated per Equation (64) using numerical integration.
The accuracy of Greene’s formula is estimated by calculating the difference per Equation (69)
of the magnetic field antenna factor found by the application of Greene’s formula and the
magnetic field antenna factor found by numerical simulation. The accuracy of the integral
formula of Equation (64) is estimated by calculating the difference per Equation (71) of the
magnetic field antenna factor found by the application of the integral formula and the magnetic
field antenna factor found by numerical simulation. The results are shown in Figure 22, where
a decreased accuracy at the upper frequency end can be observed.
(69)
∆=F FF−
aH,G aH,G aH,num
(70)
∆F= FF−
aH,I aH,I aH,num
F is the magnetic field antenna factor found by application of Greene’s formula,
aH,G
F is the magnetic field antenna factor found by application of the integral formula;
aH,I
F is the magnetic field antenna factor found by numerical simulation.
aH,num
____________
1 As discussed in e.g. 10.6 of CIS/A/1240/RM, a project is ongoing for amending CISPR 16-1-4 to include site
validation below 30 MHz; at the time of preparation of this FDIS the most recent documents for that project are
CIS/A/1323/CDV and CIS/A/1288/CC.
© IEC 2022
NOTE The feed points may be placed at the top of the loop antennas.
Figure 21 – Loop antenna pair arrangements for the TAM
Table 15 – Examples for valid use of Equation (65)
Error due to
non-constant
Loop radius Loop radius Distance
β R (ij,) rr R (i, j) current
r [m] r [m] d [m] 0 ij 0
i j ij
distribution at
30 MHz [dB]
0,05 0,3 0,39 0,31 0,061 3 0,13
0,15 0,3 0,78 0,53 0,062 4 0,33
0,05 0,15 0,31 0,22 0,061 9 0,07
0,15 0,15 0,57 0,38 0,060 8 0,18
0,05 (NOTE 1) 0,05 0,2 0,13 0,055 6 0,05
0,3 (NOTE 2) 0,3 1,2 0,8 0,055 6 0,53
NOTE 1 If both loop radii are very small, the accuracy of Greene’s formula is excellent and with an error of
only 0,05 dB.
NOTE 2 If a transmit antenna and also a receive antenna with a large radius are used, the effect of the
inhomogeneous current distribution can lead to a relatively large error of 0,53 dB.
– 10 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
Figure 22 – Accuracy of Greene’s formula and integral formula
vs. frequency for r = 0,05 m, r = 0,3 m, and d = 0,39 m
i j
© IEC 2022
a) 1,3 m above ground plane
b) 2,5 m above ground plane
Figure 23 – Examples of influence of ground plane on SIL in free-space condition
– 12 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
5.2.3.3 Measurement uncertainties for TAM calibration results
An example of the uncertainty budget estimated for TAM calibration F results at 30 MHz is
aH
shown in Table 16 and Table 18. The combined standard uncertainties for the A (i,j) SIL results
i
and the K(i,j) geometry parameter are used as inputs for the F expanded uncertainty in
aH
Table 18.
The expanded uncertainty of F measurement results depends significantly on the size of the
aH
AUC because K(i,j) per Equation (65) is a function of the separation distance, the radii of both
of the loop antennas, and misalignment.
Figure 24 shows the definitions of the parameters used in the uncertainty evaluation for K(i,j):
a) misalignment in the x-axis, uncertainty of m (not shown in Figure 24);
b) misalignment in the y-axis, uncertainty of d ;
ij
c) misalignment in the z-axis, uncertainty of l (z-axis offset);
d) misalignment around the x-axis, uncertainty of θ and θ ;
i j
e) misalignment around the y-axis, uncertainty of Θ and Θ (not shown in Figure 24);
i j
f) misalignment around the z-axis, uncertainty of φ and φ (not shown in Figure 24).
i j
It is not possible to derive the influence of misalignment with Greene’s formula, so NEC
simulations are used instead. The uncertainty component in K (given as δA ) is derived from
SIL
differences in the calculated NEC SIL values.
An easy solution to calculate measurement uncertainty is to use a mixed approach. The
uncertainty of K is calculated by a numerical method, while the remaining uncertainty
contributions are combined using the propagation of uncertainties law.
The measurement function for F is given in Equation (71).
aH
(71)
F (1)=−−45,9 20lgf + A(1,2)+ A(1,3)− A(2,3)+ KKK(1,2)+ (1,3)− (2,3)
aH MHz iii
Because the frequency inaccuracy can be neglected, the contribution from the term f is
MHz
neglected in the analysis.
The measurement function for A (i,j) is given in Equation (72).
i
δ A(i, j) δδA+ A++δA δA+δA (72)
i LIN M L SNR BS
The measurement function for K(i,j) is given in Equation (73).
δK i,j δA r ,δr ,r ,δr ,d ,δd ,δm,δl,δθ ,δθ ,δΘΘ,δ ,δφ ,δφ
( ) ( )
SIL 1 1 2 2 12 12 1 2 1 2 1 2
(73)
++δA δA
coup approx
=
=
© IEC 2022
An example source code for a measurement uncertainty Monte Carlo simulation (MCS) (e.g.
[7]) is given in Annex J.
Figure 24 – Definitions of the parameters used in
measurement uncertainty evaluation for K(i,j)
Table 16 – Example of an uncertainty budget for site insertion loss A (i,j)
i
Source of uncertainty
Probability
u
Value Divisor Sensitivity
i
or quantity X
distribution
i
dB dB
Linearity of receiver in the network
δA
0,10 Rectangular 1 0,06
LIN 3
analyzer
Transmit antenna mismatch and receive
δA
0,17 U-shaped 1 0,12
M 2
antenna mismatch
δA
Leakage between coaxial cables 0,09 Rectangular 1 0,05
L 3
δA
Signal to noise ratio 0,01 Rectangular 1 0,01
SNR 3
δA
Bending and stretching cables 0,10 Rectangular 1 0,06
BS 3
Combined standard uncertainty 0,15
NOTE The uncertainty value of signal to noise ratio depends on the measurement frequency, radii of loop
antennas, distance between two loop antennas and measuring instruments such as VNA or spectrum analyser
with tracking generator. For example, with r = r = 5 cm, d = 10 cm, frequency of 10 kHz, and a VNA is used,
1 2
then the uncertainty value of signal to noise ratio can be larger than 1,0 dB.
– 14 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
Table 17 – Example of an uncertainty budget for K(i,j) as used by the TAM
Probability
Source of uncertainty or quantity X
Value
i
distribution
δA
Positioning of loop antennas
SIL
Radius antenna 1 (r = 0,05 m) δr
0,002 m Rectangular
1 1
Radius antenna 2 (r = 0,3 m) δr
0,002 m Rectangular
2 2
Distance (misalignment in y-axis, d = 0,31 m) Δd
0,01 m Rectangular
12 12
Misalignment in x-axis δm 0,01 m Rectangular
Misalignment in z-axis δl 0,01 m Rectangular
δθ
Misalignment around x-axis, antenna 1 5° Rectangular
δΘ
Misalignment around y-axis, antenna 1 1° Rectangular
δφ
Misalignment around z-axis, antenna 1 5° Rectangular
δθ
Misalignment around x-axis, antenna 2 5° Rectangular
δΘ
Misalignment around y-axis, antenna 2 1° Rectangular
δφ
Misalignment around z-axis, antenna 2 5° Rectangular
δA
Coupling with ground plane 0,1 dB Rectangular
coup
δA
Approximation error in Equation (65) (NOTE) 0,13 dB Rectangular
approx
Expanded uncertainty, U (k = 2) 0,8 dB
NOTE If Greene’s formula [Equation (65)] is used, there is an error because the formula is only an approximation
of Equation (64). An estimation of this error is shown in Table 15 and Figure 21. This contribution does not apply
if a numerical approach is used [see Equation (67)].
Table 18 – Example of an uncertainty budget for F of a loop antenna
aH
determined by the TAM – expanded uncertainty at 30 MHz
Source of uncertainty
Probability
u
Value Divisor Sensitivity Note
i
or quantity X
distribution
i
dB dB
Normal
A (1,2)
SIL 0,15 1 1/2 0,08 See Table 16
i
(k = 1)
Normal
A (1,3)
SIL 0,15 1 1/2 0,08 See Table 16
i
(k = 1)
Normal
A (2,3)
SIL 0,15 1 −1/2 0,08 See Table 16
i
(k = 1)
r = 5 cm
Normal
r = 30 cm
Greene’s formula K(1,2) 0,8 1 1/2 0,2
(k = 2)
d = 31 cm
r = 5 cm
Normal
r = 30 cm
Greene’s formula K(1,3) 0,8 1 1/2 0,2
(k = 2)
d = 31 cm
r = 5 cm
Normal
r = 5 cm
Greene’s formula K(2,3) 1,3 1 −1/2 0,33
(k = 2)
d = 31 cm
Combined standard uncertainty, u
0,46
c
Expanded uncertainty, U (k = 2) 0,92
NOTE The contributions from Greene’s formula K(2,3) are not equal to K(1,2), K(1,3), because the result depends
on loop diameter and distance. The basis for the calculation is given in the Note column.
© IEC 2022
5.2.4 Current probe method (CPM)
5.2.4.1 General
For a CPM calibration (which is categorized as a SFM), a calculable magnetic field strength is
emitted from a single-turn unshielded circular loop antenna. The magnetic field antenna factor
of a loop AUC, F (AUC), is determined by the ratio of the magnetic field strength at the AUC,
aH
H in A/m, to the induced voltage at the AUC output, V in V, as given in Equation (74).
H
F (AUC)= in S/m (74)
aH
V
For a pair of loop antennas coaxially aligned in the near-field region of each other, as shown in
Figure 25, the transmit loop antenna carrying current I , in A, generates a magnetic field
strength, from which the average field strength at the receive loop antenna H , in dB(A/m), is
av
given by Equation (75).
H = 20lg I + 20lgS + K(1,2) in dB(A/m) (75)
av 1 1
where
S is the geometric area of the transmit loop antenna, in m ;
−3
K(1,2) is given by Equation (64), or Equation (65) for circular loops, in dB(m ).
The loop centre distance between a pair of antennas, d , should be carefully selected such that
ij
the conditions of Greene’s formula are fulfilled (see Table 15 in 5.2.3.2).
NOTE The feed point of the receive antenna may be placed at the top of the antenna
Figure 25 – Antenna arrangement for the current probe method (CPM)
5.2.4.2 Calibration procedure
Calibration of the current probe (transducer) is required to determine the loop current I for
SFM calibration measurements using CPM. If a three-port network analyzer is used with a
current probe, as shown in Figure 25 (see 5.2.4.1) [15], the transmit loop antenna element
current I , in A, can be estimated from the probe output voltage V , in V, which is measured
1 Ref
at the network analyzer reference port per Equation (76):
– 16 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
V
Ref
I = in A
1 (76)
Z
where the transfer impedance of the current probe is denoted by Z in Ω. With reference to
Equation (74) and Equation (75), the magnetic field antenna factor of a loop AUC is given by
Equation (77)
F AUC= A 1,2+ 20lgπrK+ 1,2−20lg Z in dB(S/m)
( ) ( ) ( ) (77)
( )
aH i 1
where the site insertion loss is given by Equation (78)
V
Ref
A= 20lg in dB, and
(78)
i
V
and with
r is the radius of the transmit antenna, in m;
V is the output voltage of the AUC in V, and V= V + A , in dB(V), and A represents
Test ATT ATT
the attenuation values of all attenuators and cables within the antenna #2 path;
|Z| is the current probe transfer impedance, in Ω.
The transfer impedance of the current probe, Z, shall be calibrated in accordance with the
methods in CISPR 16-1-2.
The CPM can also be implemented using a two-port network analyzer. With a two-port network
analyzer instrumentation configuration, the AUC output voltage V and transmit loop reference
voltage V are measured separately.
Ref
If a balun is used, shown in Figure 25, it shall have an impedance ratio of at least 2:1. The
reason for the balun is to decrease the source impedance to 25 Ω or less thus to increase the
current I .
Requirements for the current probe used in CPM measurements are as follows.
a) The probe body shall not influence the magnetic field strength of the transmit loop. This
condition is fulfilled if the size of the probe is small compared to the size of the loop. The
influence of the probe body shall be determined by observing the magnetic field strength
result with and without the probe present.
b) The probe cable shall not influence the magnetic field strength of the transmit loop. This
can be determined by observing the magnetic field strength while the cable is laid at different
positions. If the probe cable has an influence, ferrites can be used to reduce the influence.
c) The probe output shall not depend on the direction of the current. Some current probes
show a direction-of-current dependency at the upper end of the frequency range. This may
be estimated by rotating the probe placement on the transmit loop, if possible.
d) The probe shall normally show a flat response of the transfer impedance, and shall be
calibrated with a reasonably fine (small discretization) frequency step.
© IEC 2022
e) The position of the probe can have an effect on the measured current, due to the
inhomogeneous current distribution around the loop circumference. Typically, this effect
should be negligible due to the small radius of the loop.
5.2.4.3 Measurement uncertainties for CPM calibration results
The measurement function based on Equation (77) for a circular transmit antenna is given in
Equation (79)
F (AUC)= A(1,2)+ 20lgπrK+−(1,2) 20lg(Z)+δ A (79)
aH i ( 1 ) coup
The uncertainty of the current probe calibration measurement result is given in Table 20.
Table 19 – Example of an uncertainty budget for F of a loop antenna determined
aH
by the current probe method – expanded uncertainty at 30 MHz
Source of uncertainty
Probability
u
Value Divisor Sensitivity
i
or quantity X
distribution
i
dB
A (1,2)
Site Insertion Loss (NOTE 1) 0,15 dB Normal (k = 1) 1 1 0,15
i
r
Loop radius (NOTE 2) 0,002 m Rectangular 347 0,40
1 3
Greene’s formula (NOTE 3) K(1,2) 0,38 dB Normal (k = 1) 1 1 0,38
Transfer impedance (NOTE 4) |Z| 0,23 dB Normal (k = 1) 1 −1 0,23
δA
Coupling to vicinity (NOTE 5) 0,1 dB Rectangular 1 0,06
coup 3
Combined standard uncertainty, u
0,62
c
Expanded uncertainty, U (k = 2) 1,24
NOTE 1 See Table 16 for site insertion loss measurement uncertainty.
NOTE 2 A radius of 5 cm with an uncertainty of 2 mm is assumed for the transmit loop. The sensitivity coefficient
is equal to 40/[r ×ln(10)]; this means that the sensitivity decreases with increased transmit loop diameter.
NOTE 3 See 5.2.3.3 for the uncertainty of K(1,2). Receive antenna radius of 0,3 m and distance of 0,5 m are
assumed.
NOTE 4 See Table 20 for the uncertainty of the transfer impedance.
NOTE 5 The coupling to the vicinity is estimated by simulation or measurement. If the calibration is performed
above ground plane, Figure 23 can be used to estimate the coupling.
– 18 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
Table 20 – Example of an uncertainty budget for transfer impedance |Z|
according to the jig method of CISPR 16-1-2
Probability
Source of uncertainty
u
Value Divisor Sensitivity
i
or quantity X
i
distribution
dB dB
Reference channel reflection 0,10 U-shaped 1 0,07
Reference channel cable reflection 0,17 U-shaped 1 0,12
Coaxial adaptor jig 0,20 Rectangular 1 0,12
Connector repeatability 0,05 Rectangular 1 0,03
Instrument accuracy 0,25 Rectangular 1 0,14
Combined standard uncertainty, u
0,23
c
5.2.5 Standard antenna method
5.2.5.1 General
The standard antenna method is simple to implement because neither a third antenna nor a
current probe is required. The traceability is based on the use of a previously-calibrated antenna.
To calibrate the standard antenna, the TAM (see 5.2.3) or the TEM-cell method (see 5.2.2) may
be used.
Similarly, as with all standard calibration methods, the largest contribution to the measurement
uncertainty of the calibrated antenna factor is from the standard antenna. Therefore, the
measurement uncertainty of antenna factors obtained using SAM can be larger compared to
other methods.
5.2.5.2 Calibration procedure
The measurement setup is shown in Figure 26. The magnetic field antenna factor derived from
the SIL between two loops is described by Equation (80). If the magnetic field antenna factor
of one of the antennas is known, it is possible to calculate the second antenna factor using
Equation (80) ([72] and [73]).
(80)
F AUC =−−45,9 20lg fA+ 1,2+ K 1,2− F STA in dB(S/m)
( ) ( ) ( ) ( )
aH MHz i aH
where
A(1,2)=−20lg S (1,2) in dB, is SIL (81)
i 21
f is the frequency in MHz
MHz
K(1,2) is Greene’s formula, per Equation (64), or Equation (65) for circular loops, in
−3
dB(m ).
F (AUC) is the magnetic field antenna factor of the AUC, in dB(S/m)
aH
F (STA) is the magnetic field antenna factor of the standard antenna, in dB(S/m)
aH
© IEC 2022
NOTE The feed points may be placed at the top of the loop antennas.
Figure 26 – Antenna arrangement for the standard antenna method
5.2.5.3 Measurement uncertainties for SAM calibration results
Equation (80) serves as the measurement function, where the frequency inaccuracy is
neglected and the influence of the vicinity δA is added. An example of the measurement
coup
uncertainty budget for magnetic field antenna factor at 30 MHz is shown in Table 21. The
measurement uncertainty depends mainly on the magnetic field antenna factor of the transmit
loop antenna used as the standard antenna. In addition, the distance between the antennas
and the radii of the loop antennas affect the measurement uncertainty. For example, if the
measurement uncertainty of the transmit loop antenna factor is 1,0 dB, this calibration method
gives 1,3 dB as the expanded measurement uncertainty of the AUC.
Table 21 – Example of an uncertainty budget for F (AUC) of a loop antenna
aH
determined by the standard antenna method – expanded uncertainty at 30 MHz
Source of uncertainty
Probability
u
Value Divisor Sensitivity
i
or quantity X
distribution
i
dB dB
A (1,2)
Site Insertion Loss (NOTE 1) 0,15 Normal (k = 1) 1 1 0,15
i
Greene’s formula (NOTE 2) K(1,2) 0,38 Normal (k = 1) 1 1 0,38
(STA)
F
AF of standard antenna 1,0 Normal (k = 2) 2 −1 0,50
aH
δA
Coupling to vicinity (NOTE 3) 0,2 Rectangular 1 0,12
coup 3
Combined standard uncertainty, u
0,66
c
Expanded uncertainty, U (k = 2)
1,31
NOTE 1 See Table 16 for site insertion loss measurement uncertainty.
NOTE 2 See 5.2.3 for the uncertainty of K(1,2). A receive antenna radius of 0,3 m and distance of 0,4 m is
assumed. For the transmit loop a radius of 5 cm with an accuracy of 2 mm is assumed.
NOTE 3 The coupling to the vicinity shall be estimated by simulation or measurement. If the calibration is
performed above ground plane, Figure 23 can be used to estimate the coupling
– 20 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
6.3.2 Balance of an antenna
Update dated reference to CISPR 16-1-4:2010 to CISPR 16-1-4:2019.
Add, after the existing Annex I, added by Amendment 1, the following new annex:
© IEC 2022
Annex J
(informative)
Monte Carlo simulation of TAM loop antenna calibration
measurement uncertainty – Example source code
%%%%%%%%%%%%%%%%
% MATLAB example source code
% CISPR 16-1-6
%
% Calculation of Uncertainty for TAM
% Calculation of K
%
% Monte Carlo (MC) Simulation
%%%%%%%%%%%%%%%%%%%
clear;
M=1000; %Number of MC trials
f=30; %Frequency in MHz
%
% Defining input estimates
%
d=0.4; %Distance between antennas
u_d=0.01; %Estimate of uncertainty for distance
r1=0.05; %Radius antenna 1
u_r1=0.002; %Estimate of uncertainty for radius 1
r2=0.05; %Radius antenna 2
u_r2=0.002; %Estimate of uncertainty for radius 2
u_phi1=5; %Estimate of uncertainty for misalignment around x axis
u_phi2=5; %Estimate of uncertainty for misalignment around x axis
u_l_theta1=1; %Estimate of uncertainty for misalignment around y axis
u_l_theta2=1; %Estimate of uncertainty for misalignment around y axis
u_s_theta1=5; %Estimate of uncertainty for misalignment around z axis
– 22 – CISPR 16-1-6:2014/AMD2:2022
© IEC 2022
u_s_theta2=5; %Estimate of uncertainty for misalignment around z axis
u_m=0.01; %Estimate of uncertainty for misalignment in x axis
u_l=0.01; %Estimate of uncertainty for misalignment in z axis
%
% Setting MC samples
%
mc_d=d-u_d+2*u_d*rand(M,1);
mc_r1=r1-u_r1+2*u_r1*rand(M,1);
mc_r2=r2-u_r2+2*u_r2*rand(M,1);
mc_phi1=-u_phi1+2*u_phi1*rand(M,1);
mc_phi2=-u_phi2+2*u_phi2*rand(M,1);
mc_s_theta1=-u_s_theta1+2*u_s_theta1*rand(M,1);
mc_s_theta2=-u_s_theta2+2*u_s_theta2*rand(M,1);
mc_l_theta1=-u_l_theta1+2*u_l_theta1*rand(M,1);
mc_l_theta2=-u_l_theta2+2*u_l_theta2*rand(M,1);
mc_m=-u_m+2*u_m*rand(M,1);
mc_l=-u_l+2*u_l*rand(M,1);
%
% Calculate output estimate
%
for i=1:M
i
%call function nec; calculates SIL using NEC
SIL(i)=nec(f,mc_d(i),mc_r1(i),mc_r2(i),mc_m(i),mc_k(i),mc_phi1(i),mc_phi2(i),mc_s_theta1(i),mc_s_theta2(i),
mc_l_theta1(i),mc_l_theta2(i));
end
u_SIL=std(SIL);
%
% Other uncertainty contribution
% Measurement function is linear
© IEC 2022
%
% Unwanted coupling between the antennas and ground
u_coup=0.1; %Rectangular contribution
% Approximation error in Equation (65)
u_approx=0.13; %Rectangular contribution
%
u_K=sqrt(u_SIL^2+(u_coup/sqrt(3))^2+(u_approx/sqrt
...
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