IEC 62153-4-3:2013

IEC 62153-4-3 ®
Edition 2.0 2013-10
INTERNATIONAL
STANDARD
colour
inside
Metallic communication cable test methods –
Part 4-3: Electromagnetic compatibility (EMC) – Surface transfer impedance –
Triaxial method
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IEC 62153-4-3 ®
Edition 2.0 2013-10
INTERNATIONAL
STANDARD
colour
inside
Metallic communication cable test methods –

Part 4-3: Electromagnetic compatibility (EMC) – Surface transfer impedance –

Triaxial method
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
X
ICS 33.120.10; 33.100 ISBN 978-2-8322-1179-3

– 2 – 62153-4-3 © IEC:2013(E)
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Principle . 11
5 Test methods. 11
5.1 General . 11
5.2 Test equipment . 11
5.3 Calibration procedure . 12
5.4 Sample preparation . 12
5.5 Test set-up . 13
5.6 Test configurations . 14
5.6.1 General . 14
5.6.2 Vector network analyser with S-parameter test set . 14
5.6.3 (Vector) network analyser with power splitter . 15
5.6.4 Separate signal generator and receiver . 15
5.7 Expression of test results . 16
5.7.1 Expression . 16
5.7.2 Test report . 16
6 Test method A: Matched inner circuit with damping resistor in outer circuit . 16
6.1 General . 16
6.2 Damping resistor R . 16
6.3 Cut-off frequency . 17
6.4 Block diagram of the set-up . 17
6.5 Measuring procedure . 17
6.6 Evaluation of test results . 18
7 Test method B: Inner circuit with load resistor and outer circuit without damping
resistor . 18
7.1 General . 18
7.2 Cut-off frequency . 18
7.3 Block diagram of the set-up . 18
7.4 Measuring procedure . 19
7.5 Evaluation of test results . 20
8 Test method C: (Mismatched)-Short-Short without damping resistor . 20
8.1 General . 20
8.2 Cut-off frequency . 20
8.3 Block diagram of the set-up . 21
8.4 Measuring procedure . 21
8.5 Evaluation of test results . 21
Annex A (normative) Determination of the impedance of the inner circuit . 23
Annex B (normative) Impedance matching adapter . 24
Annex C (normative) Sample preparation for “milked on braid” method . 28
Annex D (informative) Triaxial test set-up depicted as a T-circuit . 35
Annex E (informative) Cut-off frequency of the triaxial set-up for the measurement of
the transfer impedance . 36

62153-4-3 © IEC:2013(E) – 3 –
Annex F (informative) Impact of ground loops on low frequency measurements . 42
Bibliography . 45

Figure 1 – Definition of Z . 9
T
Figure 2 – Definition of Z . 10
F
Figure 3 – Preparation of test sample for coaxial cables . 13
Figure 4 – Preparation of test sample for symmetrical cables . 13
Figure 5 – Connection to the tube . 14
Figure 6 – Test set-up using a vector network analyser with the S-parameter test set . 14
Figure 7 – 50 Ω power splitter, 2- and 3-resistor types . 15
Figure 8 – Test set-up using a network analyser (NA) and a power splitter . 15
Figure 9 – Test set-up using a signal generator and a receiver . 15
Figure 10 – Test set-up using a signal generator and a receiver with feeding resistor . 16
Figure 11 – Test set-up (principle) . 17
Figure 12 – Test set-up (principle) . 19
Figure 13 – Test set-up (principle) . 21
Figure B.1 – Impedance matching for Z < Z . 24
2 1
Figure B.2 – Impedance matching for Z > Z . 25
2 1
Figure B.3 – Coaxial impedance matching adapters (50 Ω to 75 Ω) . 26
Figure B.4 – Attenuation of 50 Ω to 75 Ω impedance matching adapter . 27
Figure C.1 – Coaxial cables: preparation of cable end “A” (1 of 2) . 29
Figure C.2 – Coaxial cables: preparation of cable end “B” . 31
Figure C.3 – Symmetrical cables: preparation of cable end “A” (1 of 2) . 32
Figure C.4 – Symmetrical cables: preparation of cable end “B” . 33
Figure C.5 – Typical resonance of end “A” . 34
Figure C.6 – Typical resonance of end “B” . 34
Figure D.1 – Triaxial set-up depicted as a T-circuit . 35
Figure E.1 – Equivalent circuit of the triaxial set-up . 36
Figure E.2 – Frequency response of the triaxial set-up for different load conditions . 38
Figure E.3 – Measurement of S of the outer circuit (tube) having a length of 50 cm . 40
Figure F.1 – Triaxial test set-up . 42
Figure F.2 – Equivalent circuits of the triaxial set-up . 43
Figure F.3 – Example showing the impact of the measurement error . 44

– 4 – 62153-4-3 © IEC:2013(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METALLIC COMMUNICATION CABLE
TEST METHODS –
Part 4-3: Electromagnetic compatibility (EMC) –
Surface transfer impedance – Triaxial method

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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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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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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
International Standard IEC 62153-4-3 has been prepared by IEC technical committee 46:
Cables, wires, waveguides, R.F. connectors, R.F. and microwave passive components and
accessories.
This second edition cancels and replaces the first edition published in 2006. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) now three different test configurations are described;
b) formulas to calculate the maximum frequency up to which the different test configurations
can be used are included (Annex E: Cut-off frequency of the triaxial set-up for the
measurement of the transfer impedance);
c) the effect of ground loops is described (Annex F: impact of ground loops on low frequency
measurements).
62153-4-3 © IEC:2013(E) – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
46/471/FDIS 46/482/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62153 series, published under the general title Metallic
communication cable test methods, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
The committee has decided that the contents of this publication will remain unchanged until
the stability 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.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.
– 6 – 62153-4-3 © IEC:2013(E)
INTRODUCTION
IEC 62153 consists of the following parts, under the general title Metallic communication
cable test methods:
Part 1-1: Metallic communication cables test methods – Part 1-1: Electrical – Measurement
of the pulse/step return loss in the frequency domain using the Inverse Discrete
Fourier Transformation (IDFT)
Part 1-2: Metallic communication cables test methods – Part 1-2: Electrical – Reflection
measurement correction
Part 4-0: Metallic communication cable test methods – Part 4-0: Electromagnetic
compatibility (EMC) – Relationship between surface transfer impedance and
screening attenuation, recommended limits
Part 4-1: Metallic communication cable test methods – Part 4-1: Electromagnetic
compatibility (EMC) – Introduction to electromagnetic (EMC) screening
measurements
Part 4-2: Metallic communication cable test methods – Part 4-2: Electromagnetic
compatibility (EMC) – Screening and coupling attenuation – Injection clamp
method
Part 4-3: Metallic communication cable test methods – Part 4-3: Electromagnetic
compatibility (EMC) – Surface transfer impedance – Triaxial method
Part 4-4: Metallic communication cable test methods – Part 4-4: Electromagnetic
compatibility (EMC) – Shielded screening attenuation, test method for measuring
of the screening attenuation as up to and above 3 GHz
Part 4-5: Metallic communication cables test methods – Part 4-5: Electromagnetic
compatibility (EMC) – Coupling or screening attenuation – Absorbing clamp
method
Part 4-6: Metallic communication cable test methods – Part 4-6: Electromagnetic
compatibility (EMC) – Surface transfer impedance – Line injection method
Part 4-7: Metallic communication cable test methods – Part 4-7: Electromagnetic
compatibility (EMC) – Test method for measuring the transfer impedance and the
screening – or the coupling attenuation – Tube in tube method
Part 4-8: Metallic communication cable test methods – Part 4-8: Electromagnetic
compatibility (EMC) – Capacitive coupling admittance
Part 4-9: Metallic communication cable test methods – Part 4-9: Electromagnetic
compatibility (EMC) – Coupling attenuation of screened balanced cables, triaxial
method
Part 4-10: Metallic communication cable test methods – Part 4-10: Electromagnetic
compatibility (EMC) – Shielded screening attenuation test method for measuring
the screening effectiveness of feed-throughs and electromagnetic gaskets double
coaxial method
Part 4-11: Metallic communication cable test methods – Part 4-11: Electromagnetic
compatibility (EMC) – Coupling attenuation or screening attenuation of patch
cords, coaxial cable assemblies, pre-connectorized cables – Absorbing clamp
method
___________
Under consideration.
62153-4-3 © IEC:2013(E) – 7 –
Part 4-12: Metallic communication cable test methods – Part 4-12: Electromagnetic
compatibility (EMC) – Coupling attenuation or screening attenuation of connecting
hardware – Absorbing clamp method
Part 4-13: Metallic communication cable test methods – Part 4-13: Electromagnetic
compatibility (EMC) – Coupling attenuation of links and channels (laboratory
conditions) – Absorbing clamp method
Part 4-14: Metallic communication cable test methods – Part 4-14: Electromagnetic
compatibility (EMC) – Coupling attenuation of cable assemblies (Field conditions)
absorbing clamp method
– 8 – 62153-4-3 © IEC:2013(E)
METALLIC COMMUNICATION CABLE
TEST METHODS –
Part 4-3: Electromagnetic compatibility (EMC) –
Surface transfer impedance – Triaxial method

1 Scope
This part of IEC 62153 determines the screening effectiveness of a cable shield by applying a
well-defined current and voltage to the screen of the cable and measuring the induced voltage
in order to determine the surface transfer impedance. This test measures only the magnetic
component of the transfer impedance.
NOTE The measurement of the electrostatic component (the capacitance coupling impedance) is described in
IEC 62153-4-8 [1] .
The triaxial method of measurement is in general suitable in the frequency range up to
30 MHz for a 1 m sample length and up to 100 MHz for a 0,3 m sample length, which
corresponds to an electrical length less than about 1/6 of the wavelength in the sample.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC/TR 62153-4-1:2010, Metallic communication cable test methods – Part 4-1:
Electromagnetic compatibility (EMC) – Introduction to electromagnetic (EMC) screening
measurements
IEC 60050 (all parts), International Electrotechnical Vocabulary (IEV) (available at
)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050 as well as
the following apply.
3.1
inner circuit
circuit consisting of the screens and the conductor(s) of the test specimen
Note 1 to entry: Quantities relating to the inner circuit are denoted by the subscript “1”. See Figure 1 and
Figure 2.
3.2
outer circuit
circuit consisting of the screen surface and the inner surface of a surrounding test jig
___________
Numbers in square brackets refer to the bibliography.

62153-4-3 © IEC:2013(E) – 9 –
Note 1 to entry: Quantities relating to the outer circuit are denoted by the subscript “2”. See Figure 1 and
Figure 2.
3.3
transfer impedance
Z
T
quotient of the longitudinal voltage induced in the matched outer circuit – formed by the
screen under test and the measuring jig – and the current fed into the inner circuit or vice
versa (see Figure 1)
U U
2 2
Z U = Z U =
Z
2 2n 2 2f
2 2
Z
T
Z
ZZ
I
U 1f
E
U
I
1n
L << λ
IEC  2697/13
U
Z =
T
I
where
Z , Z is the characteristic impedance of the inner and the outer circuits;
1 2
U , U
1 2
are the voltages in the inner and the outer circuits (n: near end, f: far end);
I
is the current in the inner circuit (n: near end, f: far end);
L is the length of the cable, respectively the length of the screen under test;
λ is the wavelength in free space.
Figure 1 – Definition of Z
T
Note 1 to entry: Transfer impedance is expressed in mΩ/m.
3.4
capacitive coupling impedance
Z
F
quotient of twice the voltage induced to the terminating impedance Z of the matched outer
circuit by a current I fed (without returning over the screen) to the inner circuit and the
current I or vice versa (see Figure 2)
– 10 – 62153-4-3 © IEC:2013(E)

I I
2n 2f
I
Z U Z U
2 2n 2 2f Z
C
T
I I
1 1
ZZ
U
U Z
1f 1
U
1n
L << λ
IEC  2698/13
I = I
2n 2f
U = U
1n 1f
I = I = (1/2) × I = I /2
2n 2f 2 2
I = I + I
2 2n 2f
U + U 2U
2n 2f 2f
Z = = = Z Z × jωC
F 1 2 T
I I
1 1
where
Z , Z is the characteristic impedance of the inner and the outer circuits;
1 2
U , U are the voltages in the inner and the outer circuits (n: near end, f: far end);
1 2
I  is the current in the inner circuit (n: near end, f: far end);
I is the current in the outer circuit (n: near end, f: far end);
C is the coupling capacitance;
T
L is the length of the cable, respectively the length of the screen under test;
λ is the wavelength in free space.
Figure 2 – Definition of Z
F
Note 1 to entry: Capacitive coupling impedance is expressed in mΩ/m
3.5
effective transfer impedance
Z
TE
3.5.1
effective transfer impedance
Z
TE
maximum absolute value of the sum or difference of the Z and Z at every frequency
F T
Z = max Z ± Z
TE F T
Note 1 to entry: The effective transfer impedance is expressed in Ω.
3.5.2
effective transfer impedance related to a reference impedance of 1 Ω
Z
TE
maximum absolute value of the sum or difference of the Z and Z at every frequency
F T
expressed in dB (Ω)
62153-4-3 © IEC:2013(E) – 11 –
 
Z
TE
 
Z =+ 20×log
TE 10
 
Z
T,ref
 
where
Z is the reference transfer impedance with a value of 1 Ω.
T,ref
Note 1 to entry: The effective transfer impedance is expressed in dB (Ω).
3.6
coupling length
L
c
length of cable which is inside the test jig, i.e. the length of the screen under test
Note 1 to entry: The coupling length together with the test method has an impact on the maximum frequency up to
which the transfer impedance could be measured. A detailed description can be found in Clause 8 of
IEC/TR 62153-4-1:2010.
3.7
cut-off frequency
maximum frequency up to which the transfer impedance can be measured
Note 1 to entry: The cut-off frequency varies with the coupling length and the used test method. A detailed
description can be found in Clause 8 of IEC/TR 62153-4-1:2010. The calculation of the cut-off frequency is
described in Annex E.
4 Principle
The test determines the screening effectiveness of a shielded cable by applying a well-
defined current and voltage to the screen of the cable and measuring the induced voltage in a
secondary circuit in order to determine the surface transfer impedance. This test measures
only the magnetic component of the transfer impedance. The measurement of the
electrostatic component (the capacitance coupling impedance) is described in IEC 62153-4-8.
The triaxial method of measurement is in general suitable in the frequency range up to
30 MHz for a 1 m sample length and up to 100 MHz for a 0,3 m sample length, which
corresponds to an electrical length less than 1/6 of the wavelength in the sample. A detailed
description can be found in Clause 8 of IEC/TR 62153-4-1:2010.
5 Test methods
5.1 General
The measurements shall be carried out at the temperature of (23 ± 3) °C.
The test method determines the transfer impedance of a cable by measuring the cable in a
triaxial test set-up. The triaxial set-up can be realised by a rigid tube or by using a milked on
braid. Different methods using different load conditions are possible and are described below.
All the different methods give the same results up to their corresponding cut-off frequency.
5.2 Test equipment
The measurements can be performed using a vector network analyser (VNA) or alternatively a
separate signal generator and a selective measuring receiver.
The measuring equipment consists of the following:
a) a vector network analyser (with an S-parameter test set); or alternatively

– 12 – 62153-4-3 © IEC:2013(E)
• a signal generator with the same characteristic impedance as the coaxial system of the
cable under test or with an impedance adapter and complemented with a power
amplifier if necessary for very high screening attenuation;
• a receiver with optional low noise amplifier for very high screening attenuation;
• the generator and receiver shall have the same system impedance:
Z = Z = Z
G R 0
b) impedance matching circuit if necessary
• primary side: nominal impedance of generator;
• secondary side: nominal impedance of the inner circuit;
• return loss: >10 dB.
Optional equipments are:
1) time domain reflectometer (TDR) with a rise time of less than 200 ps or a network
analyser with maximum frequency up to 5 GHz and time domain capability;
2) plotter.
5.3 Calibration procedure
The calibration shall be established at the same frequency points at which the measurement
of the transfer impedance is done, i.e. in a logarithmic frequency sweep over the whole
frequency range, which is specified for the transfer impedance.
When using a vector network analyser with an S-parameter test set, a full two-port calibration
shall be established including the connecting cables used to connect the test set-up to the
test equipment. The reference planes for the calibration are the connector interface of the
connecting cables.
When using a (vector) network analyser without an S-parameter test set, i.e. by using a power
splitter, a THRU calibration shall be established including the connecting cables used to
connect the test set-up to the test equipment.
When using a separate signal generator and receiver, the composite loss of the connecting
cables shall be measured and the calibration data shall be saved, so that the results may be
corrected.
 P 
 
a = 10log =−20log (S ) (1)
cal 10 10 21
 
P
 2
where
P is the power fed during the calibration procedure;
P is the power at the receiver during the calibration procedure.
If amplifiers are used, their gain shall be measured over the above-mentioned frequency
range and the data shall be saved.
If an impedance matching adapter is used, the attenuation shall be measured over the above-
mentioned frequency range and the data shall be saved (see Annex B).
5.4 Sample preparation
The test sample shall have a length not more than 50 % longer than the coupling length.
Coaxial cables are prepared as shown in Figure 3.

62153-4-3 © IEC:2013(E) – 13 –

Screen
XXXXXXXXXXXXXXXXXX
Well screened load
R
Connector
resistor R
XXXXXXXXXXXXXXXXXX
IEC  2699/13
Figure 3 – Preparation of test sample for coaxial cables
One end of the coaxial cable is loaded with a well-screened resistor, R . The value of R
1 1
depends on the test method used (as detailed below), i.e. either a short circuit or equal to the
characteristic impedance of the inner circuit, Z , or equal to the generator impedance. R is
1 1
chosen as a standard value resistor, whose resistance is close (within 10 %) to Z .
The other end is prepared with a connector to make a connection to the generator or the
impedance matching adapter (depending on the used method). All connections shall be made
so that the R.F.-contact resistance can be neglected with respect to the results.
Screened symmetrical cables are treated as a quasi-coaxial system. Therefore, the
conductors of all pairs/quads shall be connected together at both ends (other configurations
of connection are under study). All screens, including those of individually screened
pairs/quads, shall be connected together at both ends. The screens shall be connected over
the whole circumference. See also Figure 4.

Screen
XXXXXXXXXXXXXXXXXX
Well screened load
R
Connector
Pairs/quads
resistor R
XXXXXXXXXXXXXXXXXX
IEC  2700/13
Figure 4 – Preparation of test sample for symmetrical cables
5.5 Test set-up
The test sample shall be fitted to the test set-up. The test set-up is an apparatus of a triple
coaxial form. The cable screen forms both the outer conductor of the inner circuit and the
inner conductor of the outer circuit.
In the rigid set-up, the outer conductor of the outer circuit is a well-conductive tube of non-
ferromagnetic metal (for example brass, copper or aluminium) with a short circuit to the
screen on the fed side of the cable (see Figure 5).
In the flexible set-up, the outer conductor of the outer circuit is a tinned copper braid having a
coverage >70 % and braid angle <30° which is pulled over the entire length of the cable under
test (see Annex C).
– 14 – 62153-4-3 © IEC:2013(E)
Coupling length L
c
Terminating resistor
R
Cable sheath
Tube
Cable screen
Resistor R
Short circuit
IEC  2701/13
R is the terminating resistor. The value of R depends on the test method used, i.e. either a
1 1
short circuit or equal to the characteristic impedance of the inner circuit, Z or equal to the
generator impedance as detailed in the corresponding test method.
R is the damping resistor. The value of R depends on the test method used, i.e. either a
2 2
short circuit or a value as a function of the impedance of the outer circuit as detailed in the
corresponding test method.
Figure 5 – Connection to the tube
5.6 Test configurations
5.6.1 General
Depending on the available test equipment, different test configurations are available which
may – depending on the test method used – have an impact on how to convert the measured
values into the transfer impedance (see Annex D).
5.6.2 Vector network analyser with S-parameter test set
Nowadays, the common test configuration is to use a vector network analyser with an S-
parameter test set (see Figure 6).

Network analyser
Port 1 Port 2
IEC  2702/13
Figure 6 – Test set-up using a vector network analyser
with the S-parameter test set
62153-4-3 © IEC:2013(E) – 15 –
5.6.3 (Vector) network analyser with power splitter
If an S-parameter test set is not available, one can use a power splitter (see Figure 8). Power
splitters can be either a 2-resistor or a 3-resistor type (see Figure 7). When using the test
method feeding into a short (see Clause 8), the conversion from the measured scattering
parameter S to the transfer impedance will depend on the power splitter type used.
50 Ω 16,7 Ω
16,7 Ω
50 Ω 16,7 Ω
IEC  2703/13
Figure 7 – 50 Ω power splitter, 2- and 3-resistor types

Network analyser
RF
out R A B
IEC  2704/13
Figure 8 – Test set-up using a network analyser (NA) and a power splitter
5.6.4 Separate signal generator and receiver
When measuring very good screens having very low transfer impedance, the test results
could be prone to error at low frequencies due to ground loops. To avoid those ground loops,
one could use a separate generator and receiver which are either battery-driven or connected
to the power supply using disconnecting transformers (see Figure 9).
When using the test methods where the power is fed into a short (see Clause 8), one can feed
the power via a feeding resistor (the value of which is equal to the generator impedance) in
order to avoid damage of the generator (see Figure 10).

Signal
Receiver
generator
IEC  2705/13
Figure 9 – Test set-up using a signal generator and a receiver

– 16 – 62153-4-3 © IEC:2013(E)

Signal
Receiver
50 Ω resistor
generator
End "A"
End "B"
IEC  2706/13
Figure 10 – Test set-up using a signal generator and a receiver with feeding resistor
5.7 Expression of test results
5.7.1 Expression
The values of the transfer impedance are expressed as mΩ/m at the frequencies for which
requirements are specified in the relevant cable specifications.
5.7.2 Test report
The test report shall record the test results and shall conclude if the requirements of the
relevant cable specification are met.
6 Test method A: Matched inner circuit with damping resistor in outer circuit
6.1 General
In this method, the inner circuit (cable) is terminated on a matched termination (R = Z ) and
1 1
is considered as the disturbing circuit (i.e. it is fed by the generator). If the impedance of the
inner circuit is unknown, it may be measured as described in Annex A.
The outer circuit is short-circuited on the near-end side on the cable shield and connected to
the receiver on the far end via a damping resistor R .
If the impedance of the inner circuit is different from the generator impedance, then an
impedance matching adapter is used (see Annex B).
The advantage of this method is that it has a high cut-off frequency. However, the use of the
damping resistor and impedance matching adapters reduces the dynamic range.
NOTE This method is usually used with the rigid set-up.
6.2 Damping resistor R
To obtain the maximum flat bandwidth of the set-up by means of critical damping, the resistor
R should be incorporated at the far end of the outer circuit. The value of the resistor is:
D
 
R = A×60ln − 50
  (2)
d
 
ε
r1
A= 2 or A=
ε
r2
where
D is the inner diameter of the tube;
d is the outer diameter of the cable screen;
ε is the permittivity of the inner circuit;
r1
ε is the permittivity of the outer circuit.
r2
62153-4-3 © IEC:2013(E) – 17 –
6.3 Cut-off frequency
The cut-off frequency length product of this test method is (for details, see
Clause 8 of IEC/TR 62153-4-1:2010):
f × L≈ 80MHz × m (3)
cut
i.e. for a coupling length of 0,5 m the maximum frequency up to which the transfer impedance
could be measured is 160 MHz.
6.4 Block diagram of the set-up
A block diagram of the test set-up is shown in Figure 11.

Coupling length L
c Terminating resistor R = Z
1 1
Cable sheath Tube
Calibrated receiver
Input voltage U
1 or network analyser
Signal
generator
Z I
1 1 U
U
R
Z
g
Matching
circuit
Resistor R
Cable screen
IEC  2707/13
Key
Z    impedance of the generator
g
Z    impedance of the cable under test
U    input voltage in the inner circuit
U    voltage in the outer circuit
U    voltage measured by the receiver
R
L    coupling length
c
R    terminating resistor in the inner circuit
R    damping resistor
I    current in the cable screen
Figure 11 – Test set-up (principle)
6.5 Measuring procedure
The test sample shall be connected to the generator and the outer circuit (tube) to the
receiver.
The attenuation, a , shall be preferably measured in a logarithmic frequency sweep over
meas
the whole frequency range, which is specified for the transfer impedance and at the same
frequency points as for the calibration procedure:
 P 
a = 10log  =−20log (S ) (4)
meas 10 10 21
 
P
 2
– 18 – 62153-4-3 © IEC:2013(E)
where
P is the power fed to inner circuit;
P is the power in the outer circuit.
6.6 Evaluation of test results
The conversion from the measured attenuation to the transfer impedance is given by the
following formula:
 
 
 Z 
 
a −a − a +10log  
 
meas cal pad 10
 
 
Z
 
 1
 
−
 
 
 
R(Z + R )
1 0 2
 
Z = 10 (5)
T
Z L
0 c
where
Z is the system impedance (in general 50 Ω);
Z is the characteristic impedance of the inner circuit;
Z is the transfer impedance;
T
a is the attenuation measured at the measuring procedure;
meas
a is the attenuation of the connection cables if not eliminated by the calibration
cal
procedure of the test equipment;
a is the attenuation of the impedance matching adapter;
pad
L is the coupling length;
c
R is the terminating resistor in the inner circuit;
R is the series resistor in the outer circuit.
7 Test method B: Inner circuit with load resistor and outer circuit without
damping resistor
7.1 General
This method is the same as Clause 6, however without the use of the impedance matching
adapter and without the damping resistor R It has a higher dynamic range.
2.
The load resistor shall be either equal to the impedance of the inner circuit or be equal to the
generator impedance. The latter case is of interest when using a network analyser with power
splitter instead of S-parameter test set.
7.2 Cut-off frequency
The cut-off frequency length product of this test method is:
f × L≈ 25MHz × m (6)
cut
i.e. for a coupling length of 0,5 m the maximum frequency up to which the transfer impedance
could be measured is 50 MHz.
7.3 Block diagram of the set-up
A block diagram of the test set-up is shown in Figure 12.

62153-4-3 © IEC:2013(E) – 19 –

Coupling length L
c
Terminating resistor R
Cable sheath Tube
Calibrated receiver
Input voltage U
1 or network analyser
Signal
generator
I
1 U
U
R
Cable screen
IEC  2708/13
Key
U input voltage in the inner circuit
U voltage in the outer circuit
U voltage measured by the receiver
R
L coupling length
c
R  terminating resistor in the inner circuit
I current in the cable screen
Figure 12 – Test set-up (principle)
7.4 Measuring procedure
The test sample shall be connected to the generator and the outer circuit (tube) to the
receiver.
The attenuation, a , shall be preferably measured in a logarithmic frequency sweep over
meas
the whole frequency range, which is specified for the transfer impedance and at the same
frequency points as for the calibration procedure:
 P 
 
a = 10log =−20log (S ) (7)
meas 10 10 21
 
P
 
where
P is the power fed to the inner circuit;
P is the power in the outer circuit.
– 20 – 62153-4-3 © IEC:2013(E)
7.5 Evaluation of test results
The conversion from the measured attenuation to the transfer impedance is given by the
following formula:
a −a
 
meas cal
−
 
R+ Z
1 0 20
 
Z = 10 (8)
T
2L
c
where
Z is the transfer impedance;
T
Z is the system impedance (in general 50 Ω);
a is the attenuation measured at measuring procedure;
meas
a is the attenuation of the connection cables if not eliminated by the calibration
cal
procedure of the test equipment;
L is the coupling length;
c
R is the terminating resistor in inner circuit (either equal to the impedance of the inner
circuit or the impedance of the generator).
8 Test method C: (Mismatched)-Short-Short without damping resistor
8.1 General
In this method, both the inner and the outer circuits are short-circuited on one side, i.e. the
damping resistor R and the terminating resistor R (see Figure 5) are replaced by short
2 1
circuits. An impedance matching adapter is not used.
The generator feeds the outer circuit at the near end and the inner circuit (the cable under
test) is connected to the receiver at the far end. In this set-up, the influence of the capacitive
coupling is suppressed by the short circuits in the primary and secondary circuit. It is also
very sensitive and thus suitable to measure very low values of the transfer impedance (down
to 1 µΩ/m and less). Using a milked on braid as described below allows the measurement of
the transfer impedance of cable under test before, during and after mechanical tests.
NOTE This method can be used either with the rigid or the flexible (milked on braid) set-up.
8.2 Cut-off frequency
The cut-off frequency length p
...