IEC 62153-4-16:2021

IEC 62153-4-16 ®
Edition 2.0 2021-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Metallic cables and other passive components test methods –
Part 4-16: Electromagnetic compatibility (EMC) – Extension of the frequency
range to higher frequencies for transfer impedance and to lower frequencies for
screening attenuation measurements using the triaxial set-up

Méthodes d’essai des câbles métalliques et autres composants passifs –
Partie 4-16: Compatibilité électromagnétique (CEM) – Extension de la plage de
fréquences à des fréquences supérieures pour l’impédance de transfert et à des
fréquences inférieures pour mesurer l’affaiblissement d’écran à l’aide d’un
montage triaxial
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IEC 62153-4-16 ®
Edition 2.0 2021-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Metallic cables and other passive components test methods –

Part 4-16: Electromagnetic compatibility (EMC) – Extension of the frequency

range to higher frequencies for transfer impedance and to lower frequencies for

screening attenuation measurements using the triaxial set-up

Méthodes d’essai des câbles métalliques et autres composants passifs –

Partie 4-16: Compatibilité électromagnétique (CEM) – Extension de la plage de

fréquences à des fréquences supérieures pour l’impédance de transfert et à des

fréquences inférieures pour mesurer l’affaiblissement d’écran à l’aide d’un

montage triaxial
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.120.10 ISBN 978-2-8322-1010-1

– 2 – IEC 62153-4-16:2021 © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviated terms . 5
3.1 Terms and definitions . 5
3.2 Abbreviated terms . 6
4 Overview . 6
5 Frequency behaviour of the triaxial set-up . 7
6 Extrapolation of transfer impedance measurement results . 9
6.1 General . 9
6.2 Example of a measurement according to IEC 62153-4-3, Method B . 9
6.3 Example of a measurement according to IEC 62153-4-3, Method C . 10
7 Extrapolation of screening attenuation measurement results . 12
8 Determination of the relative dielectric permittivity and impedance of the inner and
outer circuits . 14
8.1 General . 14
8.2 Influence of the test head . 17
Bibliography . 20

Figure 1 – Simulation of the scattering parameter S (left hand scale) and the transfer
impedance (right hand scale) for a single braid screen . 7
Figure 2 – Comparison of formulae for conversion between forward transfer scattering
parameter and transfer impedance . 9
Figure 3 – Example of the extrapolation of the transfer impedance of an RG59 type
cable. 10
Figure 4 – Measurement of transfer impedance of a single braided cable . 11
Figure 5 – Conversion of measured scattering parameter S to the transfer impedance
M
of a single braided cable . 12
Figure 6 – Example of the extrapolation of the scattering parameter S in logarithmic
frequency scale of an RG59 type cable . 13
Figure 7 – Example of the extrapolation of the scattering parameter S in linear
frequency scale of an RG59 type cable . 14
Figure 8 – Measurement of S of the outer circuit (tube) having a length of 203 cm . 16
Figure 9 – Example of test head (COMET set-up) . 17
Figure 10 – Example of how to obtain the electrical length of the test head from the
S measurement using a bare copper wire as DUT (COMET set-up) . 18
Figure 11 – Example of an RG58 type cable in 2 m triaxial set-up (COMET) . 19

Table 1 – Parameters for simulation of triaxial set-up . 8

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METALLIC CABLES AND OTHER
PASSIVE COMPONENTS TEST METHODS –

Part 4-16: Electromagnetic compatibility (EMC) –
Extension of the frequency range to higher frequencies
for transfer impedance and to lower frequencies for screening
attenuation measurements using the triaxial set-up

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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 IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 62153-4-16 has been prepared by IEC technical committee 46: Cables, wires,
waveguides, RF connectors, RF and microwave passive components and accessories. It is an
International Standard.
This second edition cancels and replaces the first edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– Replacement of the conversion formula which was limited to a matched DUT by a new
conversion formula suitable for any load conditions.

– 4 – IEC 62153-4-16:2021 © IEC 2021
The text of this International Standard is based on the following documents:
FDIS Report on voting
46/817/FDIS 46/826/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 International Standard is English.
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.
A list of all parts in the IEC 62153 series, published under the general title Metallic cables and
other passive components test methods, can be found on the IEC website.
Future documents in this series will carry the new general title as cited above. Titles of
existing documents in this series will be updated at the time of the next edition.
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.

METALLIC CABLES AND OTHER
PASSIVE COMPONENTS TEST METHODS –

Part 4-16: Electromagnetic compatibility (EMC) –
Extension of the frequency range to higher frequencies
for transfer impedance and to lower frequencies for screening
attenuation measurements using the triaxial set-up

1 Scope
This part of IEC 62153 specifies a method to extrapolate the test results of transfer
impedance to higher frequencies and the test results of screening attenuation to lower
frequencies when measured with the triaxial set-up in accordance with IEC 62153-4-3,
IEC 62153‑4‑4 [1] and IEC 62153-4-15. This method is applicable for homogenous screens,
i.e. screens having a transfer impedance directly proportional to length. The transfer
impedance can have any frequency behaviour, i.e. it could have a behaviour where it does not
increase with 20 dB per decade as observed for screens made of a foil and a braid.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 62153-4-3:2013, Metallic communication cable test methods – Part 4-3: Electromagnetic
compatibility (EMC) – Surface transfer impedance – Triaxial method
IEC 62153-4-15, Metallic communication cable test methods – Part 4-15: Electromagnetic
compatibility (EMC) – Test method for measuring transfer impedance and screening
attenuation – or coupling attenuation with triaxial cell
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
__________
Numbers in square brackets refer to the bibliography.

– 6 – IEC 62153-4-16:2021 © IEC 2021
3.2 Abbreviated terms
CUT cable under test
DUT device under test
TDR time domain reflectometer
VNA vector network analyser
4 Overview
The triaxial set-up can be used to measure both the surface transfer impedance
(IEC 62153-4-3, IEC 62153-4-15) and the screening attenuation (IEC 62153-4-4,
IEC 62153-4-15). The transfer impedance is in general measured with a coupling length of
maximum 0,5 m resulting in an upper frequency limit of around 100 MHz, whereas the
screening attenuation is in general measured with a coupling length of 2 m to 3 m resulting in
an upper frequency limit for the transfer impedance of around 10 MHz and a lower frequency
limit for the screening attenuation of around 100 MHz (see also IEC TS 62153-4-1:2014,
Clauses 8 and 9 [2]).
Figure 1 shows the grey zone between electrically short (measurement range for the transfer
impedance) and electrically long (measurement range for the screening attenuation). The
parameters used in the simulation are:
in accordance with IEC 62153-4-3, Method B,
– forward transfer scattering parameter S
where the value of the load resistor equals the characteristic impedance of the CUT;
– impedance of inner circuit is 50 Ω;
– impedance of outer circuit is 150 Ω;
– relative dielectric permittivity of inner circuit 2,3;
– relative dielectric permittivity of outer circuit 1,1;
– coupling length 50 cm and 200 cm;
– transfer impedance calculated according to T. KLEY [3] for a copper braid design of:
diameter under braid 2,95 mm, number of spindles 16, number of wires per spindle 5, wire
diameter 0,12 mm, lay length 15 mm.
In the example shown in Figure 1, the transfer impedance can be measured up to around
30 MHz using a coupling length of 50 cm and the screening attenuation can be measured
starting from 150 MHz using a coupling length of 200 cm.
This document describes how to extrapolate the test results of transfer impedance to higher
frequencies and the test results of screening attenuation to lower frequencies when measured
with the triaxial set-up in accordance with IEC 62153-4-3, IEC 62153-4-4 and IEC 62153-4-15.

Figure 1 – Simulation of the scattering parameter S (left hand scale)
and the transfer impedance (right hand scale) for a single braid screen
5 Frequency behaviour of the triaxial set-up
Knowing the frequency behaviour of the triaxial set-up one may convert a screening
attenuation measurement to transfer impedance and vice versa. And on the other hand, one
may extend the results of the measured transfer impedance to higher frequencies.
The general equations for the coupling between the inner and outer circuit for any load
conditions are described in [3] and [4].
The relation between the measured forward transfer scattering parameter and the transfer
impedance respective screening attenuation is described in [4].
In Formula (1) the capacitive coupling through the screen is neglected. In this case the
transfer impedance Z is obtained from the measured forward transfer scattering parameter
T
S by:
M
2 ZZ
ZS ×
TM
Z =0
F
2 2
11− rr−
1n 2f
−+2 γ γL
−−22γL γ L ( )
1+ rr e + r e + rr r e (1)
1n 1f 2f 1n 1f 2f


−(γ −γL) −(γ +γL)
 
12 1 2
11−−ee
−γL −(γ +γL) −(γ −γL)
1 2 12
 
e 11−+re − re
( 1f ) ( 1f )
γγ−+γ γ
 
12 1 2
 
=
– 8 – IEC 62153-4-16:2021 © IEC 2021
For low frequencies (γL<<1) Formula (1) becomes
ZZ( + Z )
2f 1n 1f
ZS=
(2)
TM
2LZ Z
1n 2f
where
Z is the transfer impedance;
T
Z is the capacitive coupling impedance (Z = 0);
F F
S is the measured forward transfer scattering parameter;
M
L is the coupling length;
Z , Z are the characteristic impedances of the inner circuit (cable) and outer circuit
1 2
(tube), respectively;
are the wave propagation factors in the inner circuit (cable) and outer circuit
γ γ
1, 2
(tube), respectively;
r r are the reflection coefficients in the inner circuit (cable) at the near end and far
1n, 1f
end, respectively;
r is the reflection coefficient in the outer circuit (tube) at the far end.
2f
Formula (2) is the basis for the conversion formulae given in IEC 62153-4-3 and
IEC 62153‑4‑15.
Figure 2 shows the comparison between the results of transfer impedance obtained from
Formula (1) and the commonly used conversion formula between the measured forward
transfer scattering parameter and transfer impedance as described in IEC 62153-4-3. The
configuration is detailed in Table 1. The inner circuit is mismatched having a short circuit at
the far end. (i.e. method C of IEC 62153-4-3)
Table 1 – Parameters for simulation of triaxial set-up
Parameter Values
Reference impedance of VNA, Z 50 Ω
Coupling length, L 0,5 m
Impedance of inner circuit (CUT), Z 75 Ω
Load at the near end of the inner circuit, Z 50 Ω
1n
Load at the far end of the inner circuit, Z 0 Ω
1f
Dielectric permittivity of the inner circuit, ε 2,25
r1
Attenuation of the inner circuit, α 0 dB/m
Impedance of outer circuit (tube), Z 150 Ω
Load at the near end of the outer circuit, Z 0 Ω
2n
Load at the far end of the outer circuit, Z 50 Ω
2f
Dielectric permittivity of the outer circuit, ε 1,0
r2
Attenuation of the outer circuit, α 0 dB/m
DC resistance of the screen, R 13,6 mΩ/m
T
Coupling inductance of the screen, M 0,93 nH/m
T
Coupling capacitance of the screen, C 0 pF/m
T
Figure 2 – Comparison of formulae for conversion between
forward transfer scattering parameter and transfer impedance
The transfer impedance obtained from Formula (1) corresponds, as expected, to the transfer
impedance obtained from the screen parameter (R , M , and C ). But using Formula (12)
T T T
described in IEC 62153-4-3:2013 to convert the measured forward transfer scattering
parameter to transfer impedance limits the upper frequency for the transfer impedance to
about 30 MHz.
6 Extrapolation of transfer impedance measurement results
6.1 General
The test results of the transfer impedance shall be extrapolated to higher frequencies by
using Formula (1) instead of the formulae detailed in IEC 62153-4-3 and IEC 62153-4-15 to
convert the measured forward transfer scattering parameter S to the transfer impedance.
M
6.2 Example of a measurement according to IEC 62153-4-3, Method B
Figure 3 shows an example of the extrapolation of the measured transfer impedance of an
RG59 type cable. The measurement was done in accordance with IEC 62153-4-3, Method B
(matched inner circuit) with a coupling length of 2 m. For the extrapolation, a relative
dielectric permittivity of 2,3 and 1,1 was assumed for the inner circuit and outer circuit,
respectively. The blue dotted line is the measurement result obtained with a coupling length of
2 m. The green dotted line is the measurement result obtained with a coupling length of
0,5 m. The red solid line is the extrapolation of the measurement with a coupling length of
2 m.
Good concordance is observed between the from 2 m extrapolated results and the 0,5 m
measured results. The extrapolation works well up to 100 MHz. The spikes observed above
100 MHz are due to slight differences between the real and assumed dielectric permittivities.

– 10 – IEC 62153-4-16:2021 © IEC 2021
This example shows that it is possible by the use of Formula (1) to measure the transfer
impedance and screening attenuation with one and the same triaxial set-up with a coupling
length of 2 m instead of doing two measurements, one with a short coupling length for the
transfer impedance and one with a long coupling length for the screening attenuation.

Cable measured with a coupling length of 2 m and assuming relative dielectric permittivity of 2,3 and 1,1 for the
inner circuit and outer circuit, respectively.
Figure 3 – Example of the extrapolation of the transfer
impedance of an RG59 type cable
6.3 Example of a measurement according to IEC 62153-4-3, Method C
Figure 4 shows the test results of transfer impedance measurement (IEC 62153-4-3,
Method C) for a single braided coaxial cable with a 50 Ω impedance. The DUT is short
circuited at the far end (Z = 0). The results are shown for three different coupling lengths
1f
35 cm, 100 cm and 200 cm. The cut-off frequency for the transfer impedance measurement
decreases as the length increases, from 60 MHz for 35 cm to 10 MHz for 200 cm.
Figure 5 shows the conversion of the measured scattering parameter S to the transfer
M
impedance using Formula (1) instead of Formula (12) given in IEC 62153-4-3:2013. The
conversion was done using a relative dielectric permittivity of the inner circuit (DUT) of 2,3
(PE dielectric) and 1,0 of the outer circuit (cable jacket was removed). The cut-off frequency
was increased from 10 MHz for 200 cm and from 20 MHz for 100 cm respectively to 200 MHz.
The observed residual peaks at higher frequencies are due to the capacitive coupling
impedance Z which is not exactly zero and due to uncertainties in the dielectric permittivity
F
used in the conversion formula.

Cable with a 50 Ω impedance; inner circuit short circuit; coupling length 35 cm, 100 cm, 200 cm.
Figure 4 – Measurement of transfer impedance of a single braided cable

– 12 – IEC 62153-4-16:2021 © IEC 2021

Cable with a 50 Ω impedance; Formula (1); inner circuit short circuit; assuming relative dielectric permittivity of 2,3
and 1,0 for the inner circuit and outer circuit, respectively.
Figure 5 – Conversion of measured scattering parameter S
M
to the transfer impedance of a single braided cable
7 Extrapolation of screening attenuation measurement results
The test results of the screening attenuation and the measured forward transmission
scattering parameter S shall be extrapolated to lower frequencies, or in other words
M
extrapolated from a short to a long length by first converting S to the transfer impedance
M
using Formula (1). In a second step the so obtained transfer impedance is converted to the
extrapolated forward transmission scattering parameter S by:
E
2 ZZ
S ×
E
L
2 2 2
Z
T
11− rr−
1n 2f
−+2 γ γL
−−22γL γ L ( )

12 2 2 12 2
(3)
1+ r r e ++re r r re
1n 1f 2f 1n 1f 2f


− γ −γL − γ +γL
( ) ( )
1 22 1 22
11−−ee
− γ +γL − γ −γL
−γL ( ) ( )
1 22 1 22

e 11−+re − re
1f 1f
( ) ( )
γγ−+γ γ

12 1 2

=
where
S is the forward transfer scattering parameter extrapolated to length L ;
E 2
Z is the transfer impedance obtained from the measured forward transfer scattering
T
parameter S ;
M
L is the extrapolated coupling length;
Z , Z are the characteristic impedances of the inner circuit (cable) and outer circuit
1 2
(tube), respectively;
are the wave propagation factors in the inner circuit (cable) and outer circuit
γ γ
1, 2
(tube), respectively;
r r are the reflection coefficients in the inner circuit (cable) at the near end and far
1n, 1f
end, respectively;
r is the reflection coefficient in the outer circuit (tube) at the far end.
2f
Figure 6 and Figure 7 show examples of the extrapolation of the measured scattering
parameter S of an RG59 type cable.
Cable measured with a coupling length of 0,5 m and assuming dielectric permittivities of 2,3 and 1,1 for the inner
circuit and outer circuit, respectively
Figure 6 – Example of the extrapolation of the scattering parameter S
in logarithmic frequency scale of an RG59 type cable

– 14 – IEC 62153-4-16:2021 © IEC 2021

Cable measured with a coupling length of 0,5 m and assuming dielectric permittivities of 2,3 and 1,1 for the inner
circuit and outer circuit, respectively.
Figure 7 – Example of the extrapolation of the scattering parameter S
in linear frequency scale of an RG59 type cable
The measurement was done with a coupling length of 0,5 m. For the extrapolation, a dielectric
permittivity of 2,3 and 1,1 was assumed for the inner circuit and outer circuit, respectively.
The blue dotted line is the measurement result obtained with a coupling length of 0,5 m. The
green dashed line is the measurement result obtained with a coupling length of 2 m. The red
solid line is the extrapolation of the measurement with a coupling length of 0,5 m.
A good concordance is observed between the from 0,5 m extrapolated results and the 2 m
measured results. The extrapolation works well up to 300 MHz. The deviations observed
above 300 MHz are due to slight differences between the real and assumed dielectric
permittivities.
8 Determination of the relative dielectric permittivity and impedance of the
inner and outer circuits
8.1 General
In the conversion formulae, the exact dielectric permittivity and impedance of the inner and
outer circuit are needed. The relative dielectric permittivity and impedance of the inner circuit
(CUT) is in general known or may be obtained from an open/short measurement (see
IEC 61156-1:2007/AMD1:2009, 6.3.10 [5], IEC TR 62152:2009, Clause A.6 [6]) or a TDR
measurement.
For the determination of the impedance and relative dielectric permittivity of the outer circuit
(tube), one can use a TDR measurement (rise-time maximum 200 ps) or use the theory of the
transformation characteristics of a line. The input impedance of a line is expressed by the
following equation (neglecting the attenuation):

Z L
 
load
+ j tan2π 
Z λ
 
c
Z = Z (4)
in c
Z
 L 
load
1+ j tan 2π
 
Z λ
 
c
where
Z is the input impedance of the transmission line;
in
Z is the load impedance of the transmission line;
load
Z is the characteristic impedance of the transmission line;
c
is the wave length of the transmission line;
λ
L is the length of the transmission line.

For even multiples of the half wavelength (λ/2), the input impedance is equal to the load
impedance and for odd multiples of the quarter wavelength (λ/4), the transmission line acts as
a dual transformer.
With the short circuit in the outer circuit of the triaxial set-up, one gets:
Z = 0 or S = −1 when L = n λ/2
in 11
Z = ∞ or S = +1 when L = (2n+1) λ/4
in 11
So by measuring the scattering parameter S and observing two successive resonances
where the real part Re(S ) = –1 (and the imaginary part Im(S ) = 0), or two successive
11 11
resonances where the real part Re(S ) = +1 (and the imaginary part Im(S ) = 0), one can
11 11
obtain the relative dielectric permittivity:
When Re(S ) = –1 or Re(S ) = +1
11 11
 c 
ε = (5)
r  
2L∆f
 
where
ε is the relative dielectric permittivity;
r
c is the speed of light in free space;
L is the length of the transmission line;
is the frequency spacing between two successive resonances where the real part
∆f
Re(S ) = –1 (and Im(S ) = 0), or two successive resonances where the real part
11 11
Re(S ) = +1 (and Im(S ) = 0).
11 11
The observation of two successive resonances also allows for the determination of the
characteristic impedance in the outer circuit. From Formula (4), the input impedance for a
short circuited transmission line is obtained:
Z = Zjtan βL (6)
( )
in c
Z
load=0
– 16 – IEC 62153-4-16:2021 © IEC 2021
Hence:
Z = jZ for tanβL = 1, βL = (nπ + π/4), f = (4n+1)/4 ∆f
in c
or
Z = –jZ for tanβL = –1, βL = (nπ – π/4), f = (4n–1)/4 ∆f
in c
where
Z is the input impedance of the transmission line;
in
Z is the characteristic impedance of the transmission line;
c
L is the length of the transmission line;
is the phase constant of transmission line.
β
The principle of this method is shown in Figure 8, which shows the test results of a short
circuited RG58 cable having a length of 203 cm. Subclause 8.2 describes how to apply this
method to determine the relative dielectric permittivity and impedance of the outer circuit.
It is recommended to take the average frequency spacing of at least five successive
resonances as shown in Figure 8. The average frequency spacing of two successive
resonances is 48,90 MHz. Formulae (5) and (6) result in a relative dielectric permittivity of
2,28 and a characteristic impedance of 49,5 Ω which correspond to the typical values for this
type of cable.
Test results of the real part of the scattering parameter S of an RG58 type cable (with solid PE insulation) having
a length of 203 cm and a short circuit at the far end, where the average distance between two successive maxima
is 48,93 MHz and between two successive minima is 48,87 MHz, i.e. the global average distance is 48,90 MHz.
Figure 8 – Measurement of S of the outer circuit (tube) having a length of 203 cm
The characteristic impedance in the outer circuit can also be obtained if the dimensions of the
cable and the tube and the relative dielectric permittivity in the outer circuit are known:
60 D
 
(7)
Z = ln 
d
ε  
r2
where
Z is the characteristic impedance of the outer circuit in Ω;
ε is the relative dielectric permittivity of the outer circuit;
r2
D is the inner diameter of the tube in mm;
d is the outer diameter of the cable screen in mm.

8.2 Influence of the test head
To obtain the relative dielectric permittivity and impedance in the outer circuit from the
measurement of the scattering parameter S , the configuration of the triaxial tube shall be
taken into account. The well-known COMET set-up has a test head which is attached to the
measuring tube, see Figure 9.
Dimensions in millimetres
Key
characteristic impedance in the outer circuit (tube)
Z
Z characteristic impedance of the test head
Figure 9 – Example of test head (COMET set-up)
This test head is built to have a characteristic impedance of 50 Ω to match with the test
receiver. As the characteristic impedance in the outer circuit, Z is different from the
impedance of the test head, the test head will act as a line transformer and the S
measurement shall be corrected.
elec f
j4π⋅L ⋅
mech
H
cor meas j2β L meas c
H H 0
S = S × e = S × e (8)
11 11 11
– 18 – IEC 62153-4-16:2021 © IEC 2021
elec mech
L = L ε (9)
H H r,H
where
cor
S is the corrected scattering parameter S ;
11 11
meas
S is the measured scattering parameter S ;
11 11
mech
L is the mechanical length of the test head;
H
elec
L is the electrical length of the test head;
H
is the phase constant of the test head;
β
H
f is the frequency;
ε is the relative dielectric permittivity of the test head.
r,H
The electrical length of the test head can be obtained when replacing the cable in Figure 9 by
a bare copper wire. Using such a DUT, the relative dielectric permittivity in the tube is equal
to the one of air (1,00). The exact mechanical length of the tube is 948 mm, which is the
1 000 mm overall length minus 47 mm for the exceeding length of the screening cap (sleeve)
minus 5 mm for the thickness of the short circuit disc.
In this configuration, the expected frequency spacing is 158 MHz in the measurement of the
scattering parameter S measured at the test head, see Formula (5). In Figure 10, one can
observe that the results are distorted (red line) due to the line transformation of the test head.
The expected frequency spacing of 158 MHz is obtained by taking an electrical length of
175 mm for the test head. This is shown in the blue line which represents the corrected
scattering parameter S , see Formula (8).
Figure 10 – Example of how to obtain the electrical length of the test head from the S
measurement using a bare copper wire as DUT (COMET set-up)

The so determined electrical length of the test head is used to correct the results in the case
of a real CUT.
Figure 11 shows the test results of the scattering parameter S measured from the test head
with an RG58 type cable as a CUT in the 2 m tube. The results are distorted (red line) due to
the line transformation of the test head. The blue line shows the corrected results using
Formula (8) and an electrical length for the test head of 175 mm.

Figure 11 – Example of an RG58 type cable in 2 m triaxial set-up (COMET)
The exact mechanical length of the tube is 1 948 mm which is the 2 000 mm overall length
minus 47 mm for the exceeding length of the screening cap (sleeve) minus 5 mm for the
thickness of the short circuit disc. The average frequency spacing is 71,8 MHz which results
in a relative dielectric permittivity in the outer circuit of 1,15 and a characteristic impedance in
the outer circuit of 137 Ω, see Formulae (5) and (6).

– 20 – IEC 62153-4-16:2021 © IEC 2021
Bibliography
[1] IEC 62153-4-4, Metallic communication cable test methods – Part 4-4: Electromagnetic
compatibility (EMC) – Test method for measuring of the screening attenuation as up to
and above 3 GHz, triaxial method
[2] IEC TS 62153-4-1:2014, Metallic communication cable test methods – Part 4-1:
Electromagnetic compatibility (EMC) – Introduction to electromagnetic screening
measurements
[3] KLEY, T., Optimierte Kabelschirme Theorie und Messung, Diss. ETH Nr. 9354, 1991
[4] HÄHNER, T., The scattering and transfer matrix of screening effectiveness, modelling
of the triaxial setup, IWCS proceedings 2018
[5] IEC 61156-1:2007, Multicore and symmetrical pair/quad cables for digital
communications – Part 1: Generic specification
IEC 61156-1:2007/AMD1:2009
[6] IEC TR 62152:2009, Transmission properties of cascaded two-ports or quadripols –
Background of terms and definitions
[7] JUNGFER, H., Die Messung des Kopplungswiderstandes von Kabelschirmungen bei
hohen Frequenzen, NTZ, 1956, Heft 12

___________
– 22 – IEC 62153-4-16:2021 © IEC 2021
SOMMAIRE
AVANT-PROPOS . 23
1 Domaine d’application . 25
2 Références normatives . 25
3 Termes, définitions et termes abrégés . 25
3.1 Termes et définitions . 25
3.2 Termes abrégés . 26
4 Vue d’ensemble . 26
5 Comportement en fréquence du montage triaxial . 27
6 Extrapolation des résultats de mesure de l'impédance de transfert . 29
6.1 Généralités . 29
6.2 Exemple de mesurage selon l'IEC 62153-4-3, Méthode B . 29
6.3 Exemple de mesurage selon l'IEC 62153-4-3, Méthode C . 30
7 Extrapolation des résultats de mesure de l'affaiblissement d'écran . 32
8 Détermination de la permittivité diélectrique relative et de l'impédance du circuit
interne et du circuit externe, respectivement . 34
8.1 Généralités . 34
8.2 Influence de la tête d'essai . 37
Bibliographie . 41

Figure 1 – Simulation du paramètre de diffusion S (échelle de gauche) et de
l'impédance de transfert (échelle de droite) d'un écran à une seule tresse . 27
Figure 2 – Comparaison des formules de conversion entre le paramètre de diffusion de
transmission d’exécution et l'impédance de transfert . 29
Figure 3 – Exemple d'extrapolation de l'impédance de transfert d'un câble de
type RG59 . 30
Figure 4 – Mesurage de l’impédance de transfert d’un câble à tressage simple . 31
Figure 5 – Conversion du paramètre de diffusion mesuré S en impédance de transfert
M
d’un câble à tressage simple . 32
Figure 6 – Exemple d'ext
...