IEC 62153-4-7:2015

IEC 62153-4-7 ®
Edition 2.0 2015-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Metallic communication cable test methods –
Part 4-7: Electromagnetic compatibility (EMC) – Test method for measuring of
transfer impedance Z and screening attenuation a or coupling attenuation a
T s C
of connectors and assemblies up to and above 3 GHz – Triaxial tube in tube
method
Méthodes d'essai des câbles métalliques de communication –
Partie 4-7: Compatibilité électromagnétique (CEM) – Méthode d'essai pour
mesurer l'impédance de transfert Z et l'affaiblissement d'écrantage a ou
T s
l'affaiblissement de couplage a des connecteurs et des cordons jusqu'à 3 GHz
C
et au-dessus – Méthode triaxiale en tubes concentriques

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IEC 62153-4-7 ®
Edition 2.0 2015-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Metallic communication cable test methods –

Part 4-7: Electromagnetic compatibility (EMC) – Test method for measuring of

transfer impedance Z and screening attenuation a or coupling attenuation a

T s C
of connectors and assemblies up to and above 3 GHz – Triaxial tube in tube

method
Méthodes d'essai des câbles métalliques de communication –

Partie 4-7: Compatibilité électromagnétique (CEM) – Méthode d'essai pour

mesurer l'impédance de transfert Z et l'affaiblissement d'écrantage a ou
T s
l'affaiblissement de couplage a des connecteurs et des cordons jusqu'à 3 GHz
C
et au-dessus – Méthode triaxiale en tubes concentriques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100; 33.120.10 ISBN 978-2-8322-3231-6

– 2 – IEC 62153-4-7:2015 © IEC 2015
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references. 8
3 Terms and definitions . 8
4 Physical background . 10
5 Principle of the test methods . 10
5.1 General . 10
5.2 Transfer impedance . 12
5.3 Screening attenuation . 12
5.4 Coupling attenuation . 12
6 Test procedure . 13
6.1 General . 13
6.2 Tube in tube procedure . 13
6.3 Test equipment . 14
6.4 Calibration procedure . 15
6.5 Connection between extension tube and device under test . 15
6.6 Dynamic range respectively noise floor . 15
6.7 Impedance matching . 16
6.8 Influence of Adapters . 16
7 Sample preparation . 17
7.1 Coaxial connector or device . 17
7.2 Balanced or multiconductor device . 17
7.3 Cable assembly . 19
8 Measurement of transfer impedance . 19
8.1 General . 19
8.2 Principle block diagram of transfer impedance . 19
8.3 Measuring procedure – Influence of connecting cables . 19
8.4 Measuring . 20
8.5 Evaluation of test results . 20
8.6 Test report . 20
9 Screening attenuation . 21
9.1 General . 21
9.2 Impedance matching . 21
9.2.1 General . 21
9.2.2 Evaluation of test results with matched conditions . 21
9.2.3 Measuring with mismatch . 22
9.2.4 Evaluation of test results . 22
9.3 Test report . 23
10 Coupling attenuation . 23
10.1 Procedure . 23
10.2 Expression of results . 23
10.3 Test report . 24
10.4 Balunless procedure . 25
Annex A (normative) Determination of the impedance of the inner circuit . 26

Annex B (informative) Example of a self-made impedance matching adapter . 27
Annex C (informative) Measurements of the screening effectiveness of connectors
and cable assemblies . 29
C.1 General . 29
C.2 Physical basics . 29
C.2.1 General coupling equation . 29
C.2.2 Coupling transfer function . 31
C.3 Triaxial test set-up . 33
C.3.1 General . 33
C.3.2 Measurement of cable assemblies . 34
C.3.3 Measurement of connectors . 35
C.4 Conclusion . 38
Annex D (informative) Influence of contact resistances . 39
Bibliography . 41

Figure 1 – Definition of Z . 9
T
Figure 2 – Principle of the test set-up to measure transfer impedance and screening or
coupling attenuation of connectors with tube in tube . 11
Figure 3 – Principle of the test set-up to measure transfer impedance and screening
attenuation of a cable assembly . 14
Figure 4 – Principle set-up for verification test . 16
Figure 5 – Preparation of balanced or multiconductor connectors . 18
Figure 6 – Test set-up (principle) for transfer impedance measurement according to
test method B of IEC 62153-4-3 . 19
Figure 7 – Measuring the screening attenuation with tube in tube with impedance
matching device . 21
Figure 8 – Measuring the coupling attenuation with tube in tube and balun . 23
Figure 9 – Typical measurement of a connector of 0,04 m length with 1 m extension
tube . 24
Figure 10 – Measuring the coupling attenuation with multiport VNA (balunless
procedure is under consideration) . 25
Figure B.1 – Attenuation and return loss of a 50 Ω to 5 Ω impedance matching
adapter, log scale . 27
Figure B.2 – Attenuation and return loss of a 50 Ω to 5 Ω impedance matching
adapter, lin scale . 28
Figure C.1 – Equivalent circuit of coupled transmission lines . 30
Figure C.2 – Summing function S . 31
Figure C.3 – Calculated coupling transfer function (l = 1 m; e = 2,3; e = 1; Z = 0) . 32
r1 r2 F
Figure C.4 – Triaxial set-up for the measurement of the screening attenuation a and
S
the transfer impedance Z . 33
T
Figure C.5 – Simulation of a cable assembly (logarithmic scale) . 35
Figure C.6 – Simulation of a cable assembly (linear scale) . 35
Figure C.7 – Triaxial set-up with extension tube for short cable assemblies . 36
Figure C.8 – Triaxial set-up with extension tube for connectors . 36
Figure C.9 – Simulation, logarithmic frequency scale . 37
Figure C.10 – Measurement, logarithmic frequency scale. 37
Figure C.11 – Simulation, linear frequency scale . 37

– 4 – IEC 62153-4-7:2015 © IEC 2015
Figure C.12 – Measurement, linear frequency scale . 37
Figure C.13 – Simulation, logarithmic frequency scale . 38
Figure C.14 – simulation, linear frequency scale . 38
Figure D.1 – Contact resistances of the test set-up . 39
Figure D.2 – Equivalent circuit of the test set-up . 39

Table 1 – IEC 62153, Metallic communication cable test methods – Test procedures
with triaxial test set-up . 11

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METALLIC COMMUNICATION CABLE TEST METHODS –

Part 4-7: Electromagnetic compatibility (EMC) – Test method for
measuring of transfer impedance Z and screening attenuation a
T s
or coupling attenuation a of connectors and assemblies
C
up to and above 3 GHz – Triaxial tube in tube 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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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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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.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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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 62153-4-7 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:
The document is revised and updated. The changes of the revised IEC 62153-4-3:2013, and
IEC 62153-4-4:2015, are included.

– 6 – IEC 62153-4-7:2015 © IEC 2015
Measurements can be achieved now with mismatch at the generator site, impedance
matching devices are not necessary.
This bilingual version (2016-03) corresponds to the monolingual English version, published in
2015-12.
The text of this standard is based on the following documents:
FDIS Report on voting
46/572/FDIS 46/585/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.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62153 series, under the general title: Metallic communication
cable test methods, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
The contents of the corrigendum of April 2016 have been included in this copy.

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.
INTRODUCTION
The shielded screening attenuation test set-up according to IEC 62153-4-3 and
IEC 62153-4-4 have been extended to take into account the particularities of electrically short
elements like connectors and cable assemblies. Due to the concentric outer tube of the
triaxial set-up, measurements are independent of irregularities on the circumference and outer
electromagnetic fields.
With the use of an additional resonator tube (inner tube respectively tube in tube), a system is
created where the screening effectiveness of an electrically short device is measured in
realistic and controlled conditions. Also a lower cut off frequency for the transition between
electrically short (transfer impedance Z ) and electrically long (screening attenuation a ) can
T S
be achieved.
A wide dynamic and frequency range can be applied to test even super screened connectors
and assemblies with normal instrumentation from low frequencies up to the limit of defined
transversal waves in the outer circuit at approximately 4 GHz.

– 8 – IEC 62153-4-7:2015 © IEC 2015
METALLIC COMMUNICATION CABLE TEST METHODS –

Part 4-7: Electromagnetic compatibility (EMC) – Test method for
measuring of transfer impedance Z and screening attenuation a
T s
or coupling attenuation a of connectors and assemblies
C
up to and above 3 GHz – Triaxial tube in tube method

1 Scope
This triaxial method is suitable to determine the surface transfer impedance and/or screening
attenuation and coupling attenuation of mated screened connectors (including the connection
between cable and connector) and cable assemblies. This method could also be extended to
determine the transfer impedance, coupling or screening attenuation of balanced or multipin
connectors and multicore cable assemblies. For the measurement of transfer impedance and
screening- or coupling attenuation, only one test set-up is needed.
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 TS 62153-4-1, Metallic communication cable test methods – Part 4-1: Electromagnetic
compatibility (EMC) – Introduction to electromagnetic screening measurements
IEC 62153-4-3, Metallic communication cable test methods – Part 4-3: Electromagnetic
Compatibility (EMC) − Surface transfer impedance − Triaxial method
IEC 62153-4-4, 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
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 and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
surface transfer impedance
Z
T
for an electrically short screen, quotient of the longitudinal voltage U induced to the inner
circuit by the current I fed into the outer circuit or vice versa, see figure 1
Note 1 to entry: The surface transfer impedance is expressed in ohms.
Note 2 to entry: The value Z of an electrically short screen is expressed in ohms [Ω] or decibels in relation to
T
1 Ω.
Note 3 to entry: See Figure 1.

I I
2 2
l < λ/10
U
IEC
Figure 1 – Definition of Z
T
U
Z = (1)
T
I
 Z 
T
Z dB(Ω)=+20×log   (2)
T 10
 
1Ω
 
3.2
effective transfer impedance
Z
TE
effective transfer impedance, defined as:
Z = max Z ± Z (3)
TE F T
where
Z is the capacitive coupling impedance.
F
3.3
screening attenuation
a
s
for electrically long devices, i.e. above the cut-off frequency, logarithmic ratio of the feeding
power P and the periodic maximum values of the coupled power P in the outer circuit
1 r,max
 
P
r,max
 
a=−10log Env (4)
s 10


P
 
where
Env is the minimum envelope curve of the measured values in dB
Note 1 to entry: The screening attenuation of an electrically short device is defined as:
150Ω
a=− 20log (5)
s 10
Z
TE
where
150 Ω is the standardized impedance of the outer circuit.

– 10 – IEC 62153-4-7:2015 © IEC 2015
3.4
coupling attenuation
a
C
for a screened balanced device, the sum of the unbalance attenuation a of the symmetric
U
pair and the screening attenuation a of the screen of the device under test
S
Note 1 to entry: For electrically long devices, i.e. above the cut-off frequency, the coupling attenuation a is
C
defined as the logarithmic ratio of the feeding power P and the periodic maximum values of the coupled power
P in the outer circuit.
r,max
3.5
coupling length
length of cable inside the test jig between the end of the extension tube and the screening
cap (see Figure 2)
Note 1 to entry: the coupling length is electrically short, if
c
λ
o
o
>10⋅ ε or f< (6)
r1
l
10⋅ l⋅ ε
r1
or electrically long, if
C
λ
o
o
≤ 2⋅ ε – ε or f> (7)
r1 r2
l
2⋅l⋅ ε – ε
r1 r2
where
l is the effective coupling length in m;
λ is the free space wave length in m;
o
ε is the resulting relative permittivity of the dielectric of the cable;
r1
ε is the resulting relative permittivity of the dielectric of the secondary circuit;
r2
f is the frequency in Hz;
c is the velocity of light in free space.
o
3.6
device under test
device consisting of the mated connectors with their attached cables
4 Physical background
See respective clauses of IEC TS 62153-4-1, IEC 62153-4-3, IEC 62153-4-4 and Annexes C
and D.
5 Principle of the test methods
5.1 General
The IEC 62153-4-x series describes different test procedures to measure screening
effectiveness on communication cables, connectors and components with triaxial test set-up.
Table 1 gives an overview about IEC 62153-4-x test procedures with triaxial test set-up.

Table 1 – IEC 62153, Metallic communication cable test methods –
Test procedures with triaxial test set-up
Metallic Communication Cable test methods − Electromagnetic compatibility (EMC)
IEC TR 62153-4-1 Ed.3 Introduction to electromagnetic (EMC) screening measurements
IEC 62153-4-3 Ed.2
Surface transfer impedance − Triaxial method
IEC 62153-4-4Ed.2 Shielded screening attenuation, test method for measuring of the screening attenuation
a up to and above 3 GHz
s
IEC 62153-4-7 Shielded screening attenuation test method for measuring the transfer impedance Z and
T
the screening attenuation a or the coupling attenuation a of RF-connectors and
s c
assemblies up to and above 3 GHz, tube in tube method
IEC 62153-4-9 Coupling attenuation of screened balanced cables, triaxial method
IEC 62153-4-10 Shielded screening attenuation test method for measuring the screening effectiveness of
feedtroughs and electromagnetic gaskets double coaxial method
IEC 62153-4-15
Test method for measuring transfer impedance and screening attenuation − or coupling
attenuation with triaxial cell (under consideration)
IEC 62153-4-16 Technical report on the relationship between transfer impedance and screening
attenuation (under consideration)

Usually RF connectors have mechanical dimensions in the longitudinal axis in the range of
20 mm to maximum 50 mm. With the definition of electrical short elements we get cut off or
corner frequencies for the transition between electrically short and long elements of about
1 GHz or higher for usual RF-connectors.
To measure the screening attenuation instead of transfer impedance also in the lower
frequency range, the tube in tube procedure was designed. The electrically length of the RF-
connector is extended by a RF-tightly closed metallic extension tube (tube in tube). See
Figure 2.
Measuring
Connector
tube
under test
Matching resistor
Generator
R = Z
1 1
Receiver
Screening cap
Extension tube
Connecting cable
IEC
Figure 2 – Principle of the test set-up to measure transfer impedance
and screening or coupling attenuation of connectors with tube in tube
The tube in tube test set up is based on the triaxial system according to IEC 62153-4-3 and
IEC 62153-4-4 consisting of the DUT, a solid metallic tube and (optional) a RF-tight extension
tube. The matched device under test, DUT, which is fed by a generator, forms the disturbing
circuit which may also be designated as the inner or the primary circuit. The connecting
cables to the DUT are additionally screened by the tube in tube.

– 12 – IEC 62153-4-7:2015 © IEC 2015
The disturbed circuit, which may also be designated as the outer or the second circuit, is
formed by the outer conductor of the device under test (and the extension tube), connected to
the connecting cable and a solid metallic tube, having the DUT under test in its axis.
5.2 Transfer impedance
The test determines the screening effectiveness of a shielded cable by applying a well-
defined current and voltage to the screen of the cable, the assembly or the device under test
and measuring the induced voltage in secondary circuit in order to determine the surface
transfer impedance. This test measures only the magnetic component of the transfer
impedance. To measure the electrostatic component (the capacitance coupling impedance),
the method described in IEC 62153-4-8 should be used.
The triaxial method of the measurement is in general suitable in the frequency range up to
30 MHz for a 1 m sample length and 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 is
found in Clause 9 of IEC TS 62153-4-1:2014 as well as in IEC 62153-4-3.
5.3 Screening attenuation
The disturbing or primary circuit is the matched cable, assembly or device under test. The
disturbed or secondary circuit consists of the outer conductor (or the outermost layer in the
case of multiscreen cables or devices) of the cable or the assembly or the device under test
and a solid metallic housing, having the device under test in its axis (see Figure 3).
The voltage peaks at the far end of the secondary circuit have to be measured. The near end
of the secondary circuit is short-circuited. For this measurement, a matched receiver is not
necessary. The expected voltage peaks at the far end are not dependent on the input
impedance of the receiver, provided that it is lower than the characteristic impedance of the
secondary circuit. However, it is an advantage to have a low mismatch, for example, by
selecting of housings of sufficient size. A detailed description could be found in Clause 10 of
IEC TS 62153-4-1:2014 as well as in IEC 62153-4-4.
5.4 Coupling attenuation
Balanced cables, connectors, assemblies or devices which are driven in the differential mode
may radiate a small part of the input power, due to irregularities in the symmetry. For
unscreened balanced cables, connectors, assemblies or devices, this radiation is related to
the unbalance attenuation a . For screened balanced cables, connectors or assemblies, the
u
unbalance causes a current in the screen which is then coupled by the transfer impedance
and capacitive coupling impedance into the outer circuit. The radiation is attenuated by the
screen of the component and is related to the screening attenuation a .
s
Consequently the effectiveness against electromagnetic disturbances of shielded balanced
cables, connectors or assemblies is the sum of the unbalance attenuation a of the pair and
u
the screening attenuation a of the screen. Since both quantities usually are given in a
s
logarithmic ratio, they may simply be added to form the coupling attenuation a :
c
a = a +a (8)
c u s
Coupling attenuation a is determined from the logarithmic ratio of the feeding power P and
c 1
the periodic maximum values of the power P (which may be radiated due to the peaks of
r,max
voltage U in the outer circuit):
 
P
r,max
 
a = –10 log Env (9)
c 10
 
P
 
where
Env is the minimum envelope curve of the measured values in dB.
The relationship of the radiated power P to the measured power P received on the input
r 2
impedance R is:
P P R
s S max
= = (10)
P P 2⋅ Z
2 2max s
There will be a variation of the voltage U on the far end, caused by the electromagnetic
coupling through the screen and superposition of the partial waves caused by the surface
transfer impedance Z ,the capacitive coupling impedance Z (travelling to the far and near
T F
end) and the totally reflected waves from the near end.
To feed the balanced device under test, a differential mode signal is necessary. This can be
achieved with a two-port network analyser (generator and receiver) and a balun or a multiport
network analyser. The procedure to measure coupling attenuation with a multiport network
analyser is under consideration.
6 Test procedure
6.1 General
The measurements shall be carried out at the temperature of (23 ± 3) °C. The test method
determines the transfer impedance or the screening attenuation or the coupling attenuation of
a DUT by measuring in a triaxial test set-up according to IEC 62153-4-3 and IEC 62153-4-4.
6.2 Tube in tube procedure
Usually RF connectors have mechanical dimensions in the longitudinal axis in the range of
20 mm to maximum 50 mm. With the definition of electrically short elements, we get cut off or
corner frequencies or corner for the transition between electrically short and long elements of
about 1 GHz or higher for usual RF-connectors.
In the frequency range up to the cut off frequency, where the device under test (DUT) is
electrically short, the transfer impedance of the DUT can be measured. For frequencies above
the cut-off frequency, where the DUT is electrically long, the screening attenuation can be
measured.
By extending the electrically length of the RF-connector by a RF-tightly closed metallic
extension tube (tube in tube), the tested combination becomes electrically long and the cut-off
frequency is moved towards the lower frequency range. In this way, also in the lower
frequency range, the screening attenuation may be measured and the effective transfer
impedance of electrical short devices calculated.
The test set up is a triaxial system consisting of the DUT, a solid metallic tube and a RF-tight
extension tube. The matched device under test, DUT, which is fed by a generator forms the
disturbing circuit which may also be designated as the inner or the primary circuit.
The disturbed circuit, which may also be designated as the outer or the second circuit, is
formed by the outer conductor of the device under test, connected to the extension tube and a
solid metallic tube having the DUT under test in its axis.
The principle of the test set-up is shown in Figure 2 and Figure 3. The set-up is the same for
measuring the transfer impedance and the screening- or the coupling attenuation, whereas
the length of the inner and the outer tube may vary.

– 14 – IEC 62153-4-7:2015 © IEC 2015
Measuring tube
Connector interface
Assembly
under test Matching resistor
R = Z
1 1
Generator
Receiver
Screening cap
Connecting cable
Extension tube,
variable length
IEC
Figure 3 – Principle of the test set-up to measure transfer impedance
and screening attenuation of a cable assembly
The voltage ratio of the voltage at the near end (U ) of the inner circuit (generator) and the
voltage at the far end (U ) of the secondary circuit (receiver) shall be measured (U /U ). The
2 1 2
near end of the secondary circuit is short-circuited.
Depending on the electrical length of the tested combination, the DUT and the extension tube,
the result may be expressed either by the transfer impedance, the effective transfer
impedance or the screening attenuation (or the coupling attenuation).
For this measurement, a matched receiver is not necessary. The likely voltage peaks at the
far end are not dependant on the input impedance of the receiver, provided that it is lower
than the characteristic impedance of the secondary circuit. However, it is an advantage to
have a low mismatch, for example by selecting a range of tube diameters for several sizes of
coaxial cables.
6.3 Test equipment
The principle of the test set-up is shown in Figure 2 and 3 and consists of:
– an apparatus of a triple coaxial form with a length sufficient to produce a superimposition
of waves in narrow frequency bands which enable the envelope curve to be drawn,
– tubes with variable lengths, e.g. by different parts of the tubes and/or by a movable tube in
tube. In case of larger connectors or components, the triaxial tubes may be replaced by a
triaxial cell according to IEC 62153-15.
– a RF-tight extension tube (tube in tube), variable in length, which should preferably have a
diameter such that the characteristic impedance to the outer tube is 50 Ω or equal to the
nominal characteristic wave impedance of the network analyser or the generator and
receiver. The material of the extension tube shall be non ferromagnetic and well
conductive (copper or brass) and shall have a thickness ≥1 mm such that the transfer
impedance is negligible compared to the transfer impedance of the device under test,
– a signal generator and a receiver with a calibrated step attenuator and a power amplifier if
necessary for very high screening attenuation. The generator and the receiver may be
included in a network analyser.
– a balun for impedance matching of the unbalanced generator output signal to the
characteristic wave impedance of balanced cables for measuring the coupling attenuation.
Requirements for the balun are given in IEC 62153-4-9:2008, 6.2. Alternatively to a balun,
a VNA with mixed mode option may be used (procedures with mixed mode VNAs are
under consideration).
Optional equipment is:
– time domain reflectometer (TDR) with a rise time of less than 200 ps or network analyser
with maximum frequency up to 5 GHz and time domain capability.
6.4 Calibration procedure
The calibration shall be established at the same frequency points at which the measurement
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 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 S-parameter test-set, i.e. by using a power
splitter, a THRU calibration shall be established including the test leads used to connect the
test set-up to the test equipment.
When using a separate signal generator and receiver, the composite loss of the test leads
shall be measured and the calibration data shall be saved, so that the results may be
corrected.
 
P
 
a = 10 log
...

IEC 62153-4-7 ®
Edition 2.1 2018-05
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Metallic communication cable test methods –
Part 4-7: Electromagnetic compatibility (EMC) – Test method for measuring of
transfer impedance Z and screening attenuation a or coupling attenuation a
T s C
of connectors and assemblies up to and above 3 GHz – Triaxial tube in tube
method
Méthodes d'essai des câbles métalliques de communication –
Partie 4-7: Compatibilité électromagnétique (CEM) – Méthode d'essai pour
mesurer l'impédance de transfert Z et l'affaiblissement d'écrantage a ou
T s
l'affaiblissement de couplage a des connecteurs et des cordons jusqu'à 3 GHz
C
et au-dessus – Méthode triaxiale en tubes concentriques

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IEC 62153-4-7 ®
Edition 2.1 2018-05
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Metallic communication cable test methods –

Part 4-7: Electromagnetic compatibility (EMC) – Test method for measuring of

transfer impedance Z and screening attenuation a or coupling attenuation a
T s C
of connectors and assemblies up to and above 3 GHz – Triaxial tube in tube

method
Méthodes d'essai des câbles métalliques de communication –

Partie 4-7: Compatibilité électromagnétique (CEM) – Méthode d'essai pour

mesurer l'impédance de transfert Z et l'affaiblissement d'écrantage a ou
T s
l'affaiblissement de couplage a des connecteurs et des cordons jusqu'à 3 GHz
C
et au-dessus – Méthode triaxiale en tubes concentriques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.10; 33.120.10 ISBN 978-2-8322-5701-2

IEC 62153-4-7 ®
Edition 2.1 2018-05
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Metallic communication cable test methods –
Part 4-7: Electromagnetic compatibility (EMC) – Test method for measuring of
transfer impedance Z and screening attenuation a or coupling attenuation a
T s C
of connectors and assemblies up to and above 3 GHz – Triaxial tube in tube
method
Méthodes d'essai des câbles métalliques de communication –
Partie 4-7: Compatibilité électromagnétique (CEM) – Méthode d'essai pour
mesurer l'impédance de transfert Z et l'affaiblissement d'écrantage a ou
T s
l'affaiblissement de couplage a des connecteurs et des cordons jusqu'à 3 GHz
C
et au-dessus – Méthode triaxiale en tubes concentriques

– 2 – IEC 62153-4-7:2015+AMD1:2018 CSV

© IEC 2018
CONTENTS
FOREWORD . 5

INTRODUCTION . 7

1 Scope . 8

2 Normative references . 8

3 Terms and definitions . 8

4 Physical background . 10

5 Principle of the test methods . 10
5.1 General . 10
5.2 Transfer impedance . 12
5.3 Screening attenuation . 12
5.4 Coupling attenuation . 12
6 Test procedure . 13
6.1 General . 13
6.2 Tube in tube procedure . 13
6.3 Test equipment . 14
6.4 Calibration procedure . 15
6.5 Connection between extension tube and device under test . 15
6.6 Dynamic range respectively noise floor . 15
6.7 Impedance matching . 16
6.8 Influence of Adapters . 16
7 Sample preparation . 17
7.1 Coaxial connector or device . 17
7.2 Balanced or multiconductor device . 17
7.3 Cable assembly . 19
8 Measurement of transfer impedance . 19
8.1 General . 19
8.2 Principle block diagram of transfer impedance . 19
8.3 Measuring procedure – Influence of connecting cables . 19
8.4 Measuring . 20
8.5 Evaluation of test results . 20
8.6 Test report . 20

9 Screening attenuation . 21
9.1 General . 21
9.2 Impedance matching . 21
9.2.1 General . 21
9.2.2 Evaluation of test results with matched conditions . 21
9.2.3 Measuring with mismatch. 22
9.2.4 Evaluation of test results . 22
9.3 Test report . 23
10 Coupling attenuation . 23
10.1 Procedure . 23
10.2 Expression of results . 23
10.3 Test report . 24
10.4 Balunless procedure . 25

© IEC 2018
Annex A (normative) Determination of the impedance of the inner circuit . 26

Annex B (informative) Example of a self-made impedance matching adapter . 27

Annex C (informative) Measurements of the screening effectiveness of connectors

and cable assemblies . 29

C.1 General . 29

C.2 Physical basics . 29

C.2.1 General coupling equation . 29

C.2.2 Coupling transfer function . 31

C.3 Triaxial test set-up . 33

C.3.1 General . 33
C.3.2 Measurement of cable assemblies . 34
C.3.3 Measurement of connectors . 35
C.4 Conclusion . 38
Annex D (informative) Influence of contact resistances . 39
Annex E (informative) Direct measurement of screening effectiveness of connectors . 41
E.1 General . 41
E.2 Test set-up . 41
E.3 Construction details of test set-up . 42
Bibliography . 44

Figure 1 – Definition of Z . 9
T
Figure 2 – Principle of the test set-up to measure transfer impedance and screening or
coupling attenuation of connectors with tube in tube . 11
Figure 3 – Principle of the test set-up to measure transfer impedance and screening
attenuation of a cable assembly . 14
Figure 4 – Principle set-up for verification test . 16
Figure 5 – Preparation of balanced or multiconductor connectors . 18
Figure 6 – Test set-up (principle) for transfer impedance measurement according to
test method B of IEC 62153-4-3 . 19
Figure 7 – Measuring the screening attenuation with tube in tube with impedance
matching device . 21
Figure 8 – Measuring the coupling attenuation with tube in tube and balun . 23
Figure 9 – Typical measurement of a connector of 0,04 m length with 1 m
extension tube . 24

Figure 10 – Measuring the coupling attenuation with multiport VNA (balunless
procedure is under consideration) . 25
Figure B.1 – Attenuation and return loss of a 50 Ω to 5 Ω impedance matching
adapter, log scale . 27
Figure B.2 – Attenuation and return loss of a 50 Ω to 5 Ω impedance matching
adapter, lin scale . 28
Figure C.1 – Equivalent circuit of coupled transmission lines . 30
Figure C.2 – Summing function S . 31
Figure C.3 – Calculated coupling transfer function (l = 1 m; e = 2,3; e = 1; Z = 0) . 32
r1 r2 F
Figure C.4 – Triaxial set-up for the measurement of the screening attenuation a and
S
the transfer impedance Z . 33
T
Figure C.5 – Simulation of a cable assembly (logarithmic scale) . 35
Figure C.6 – Simulation of a cable assembly (linear scale) . 35

– 4 – IEC 62153-4-7:2015+AMD1:2018 CSV

© IEC 2018
Figure C.7 – Triaxial set-up with extension tube for short cable assemblies . 36

Figure C.8 – Triaxial set-up with extension tube for connectors . 36

Figure C.9 – Simulation, logarithmic frequency scale . 37

Figure C.10 – Measurement, logarithmic frequency scale . 37

Figure C.11 – Simulation, linear frequency scale. 37

Figure C.12 – Measurement, linear frequency scale . 37

Figure C.13 – Simulation, logarithmic frequency scale . 38

Figure C.14 – simulation, linear frequency scale . 38

Figure D.1 – Contact resistances of the test set-up . 39
Figure D.2 – Equivalent circuit of the test set-up . 39
Figure E.1 – Principle of the test set-up to measure transfer impedance and screening
attenuation of a connector . 41
Figure E.2 – Principle of the test set-up to measure transfer impedance and screening
attenuation of a cable assembly . 42
Figure E.3 – Example of sample preparing . 42
Figure E.4 – Screening tube with separate nut . 43
Figure E.5 – Screening fixed with associated nut . 43
Table 1 – IEC 62153, Metallic communication cable test methods – Test procedures
with triaxial test set-up . 11

© IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
METALLIC COMMUNICATION CABLE TEST METHODS –

Part 4-7: Electromagnetic compatibility (EMC) – Test method for

measuring of transfer impedance Z and screening attenuation a
T s
or coupling attenuation a of connectors and assemblies
C
up to and above 3 GHz – Triaxial tube in tube 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
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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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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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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.
This consolidated version of the official IEC Standard and its amendment has been prepared
for user convenience.
IEC 62153-4-7 edition 2.1 contains the second edition (2015-12) [documents 46/572/FDIS and
46/585/RVD], its corrigendum 1 (2016-04) and its amendment 1 (2018-05) [documents 46/679/
FDIS and 46/682/RVD].
In this Redline version, a vertical line in the margin shows where the technical content is
modified by amendment 1. Additions are in green text, deletions are in strikethrough red text. A
separate Final version with all changes accepted is available in this publication.

– 6 – IEC 62153-4-7:2015+AMD1:2018 CSV

© IEC 2018
International Standard IEC 62153-4-7 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 constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous
edition:
The document is revised and updated. The changes of the revised IEC 62153-4-3:2013, and
IEC 62153-4-4:2015, are included.
Measurements can be achieved now with mismatch at the generator site, impedance
matching devices are not necessary.
This bilingual version (2016-03) corresponds to the monolingual English version, published
in 2015-12.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62153 series, under the general title: Metallic communication
cable test methods, can be found on the IEC website.
The committee has decided that the contents of the base publication and its amendment 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.
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.
© IEC 2018
INTRODUCTION
The shielded screening attenuation test set-up according to IEC 62153-4-3 and

IEC 62153-4-4 have been extended to take into account the particularities of electrically short

elements like connectors and cable assemblies. Due to the concentric outer tube of the

triaxial set-up, measurements are independent of irregularities on the circumference and outer

electromagnetic fields.
With the use of an additional resonator tube (inner tube respectively tube in tube), a system is

created where the screening effectiveness of an electrically short device is measured in

realistic and controlled conditions. Also a lower cut off frequency for the transition between

) and electrically long (screening attenuation a ) can
electrically short (transfer impedance Z
T S
be achieved.
A wide dynamic and frequency range can be applied to test even super screened connectors
and assemblies with normal instrumentation from low frequencies up to the limit of defined
transversal waves in the outer circuit at approximately 4 GHz.

– 8 – IEC 62153-4-7:2015+AMD1:2018 CSV

© IEC 2018
METALLIC COMMUNICATION CABLE TEST METHODS –

Part 4-7: Electromagnetic compatibility (EMC) – Test method for

measuring of transfer impedance Z and screening attenuation a
T s
or coupling attenuation a of connectors and assemblies
C
up to and above 3 GHz – Triaxial tube in tube method

1 Scope
This triaxial method is suitable to determine the surface transfer impedance and/or screening
attenuation and coupling attenuation of mated screened connectors (including the connection
between cable and connector) and cable assemblies. This method could also be extended to
determine the transfer impedance, coupling or screening attenuation of balanced or multipin
connectors and multicore cable assemblies. For the measurement of transfer impedance and
screening- or coupling attenuation, only one test set-up is needed.
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 TS 62153-4-1, Metallic communication cable test methods – Part 4-1: Electromagnetic
compatibility (EMC) – Introduction to electromagnetic screening measurements
IEC 62153-4-3, Metallic communication cable test methods – Part 4-3: Electromagnetic
Compatibility (EMC) − Surface transfer impedance − Triaxial method
IEC 62153-4-4, 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
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 and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
surface transfer impedance
Z
T
for an electrically short screen, quotient of the longitudinal voltage U induced to the inner
circuit by the current I fed into the outer circuit or vice versa, see figure 1
Note 1 to entry: The surface transfer impedance is expressed in ohms.
Note 2 to entry: The value Z of an electrically short screen is expressed in ohms [Ω] or decibels in relation to
T
1 Ω.
Note 3 to entry: See Figure 1.

© IEC 2018
I I
2 2
l < λ/10
U
IEC
Figure 1 – Definition of Z
T
U
Z = (1)
T
I
 Z 
T
 
Z dB(Ω)=+20×log (2)
T 10
 
1Ω
 
3.2
effective transfer impedance
Z
TE
effective transfer impedance, defined as:
Z = max Z ± Z (3)
TE F T
where
Z is the capacitive coupling impedance.
F
3.3
screening attenuation
a
s
for electrically long devices, i.e. above the cut-off frequency, logarithmic ratio of the feeding
power P and the periodic maximum values of the coupled power P in the outer circuit
1 r,max
 
P
r,max
 
a=−10log Env (4)
s 10
 
P


where
Env is the minimum envelope curve of the measured values in dB
Note 1 to entry: The screening attenuation of an electrically short device is defined as:
150Ω
a=− 20log (5)
s 10
Z
TE
where
150 Ω is the standardized impedance of the outer circuit.

– 10 – IEC 62153-4-7:2015+AMD1:2018 CSV

© IEC 2018
3.4
coupling attenuation
a
C
for a screened balanced device, the sum of the unbalance attenuation a of the symmetric
U
pair and the screening attenuation a of the screen of the device under test
S
Note 1 to entry: For electrically long devices, i.e. above the cut-off frequency, the coupling attenuation a is
C
defined as the logarithmic ratio of the feeding power P and the periodic maximum values of the coupled power

P in the outer circuit.
r,max
3.5
coupling length
length of cable inside the test jig between the end of the extension tube and the screening
cap (see Figure 2)
Note 1 to entry: the coupling length is electrically short, if
c
λ
o
o
>10⋅ ε or f< (6)
r1
l
10⋅ l⋅ ε
r1
or electrically long, if
C
λ
o
o
≤ 2⋅ ε – ε or f> (7)
r1 r2
l
2⋅l⋅ ε – ε
r1 r2
where
l is the effective coupling length in m;
λ is the free space wave length in m;
o
ε is the resulting relative permittivity of the dielectric of the cable;
r1
ε is the resulting relative permittivity of the dielectric of the secondary circuit;
r2
f is the frequency in Hz;
c is the velocity of light in free space.
o
3.6
device under test
device consisting of the mated connectors with their attached cables
4 Physical background
See respective clauses of IEC TS 62153-4-1, IEC 62153-4-3, IEC 62153-4-4 and Annexes C
and D.
5 Principle of the test methods
5.1 General
The IEC 62153-4-x series describes different test procedures to measure screening
effectiveness on communication cables, connectors and components with triaxial test set-up.
Table 1 gives an overview about IEC 62153-4-x test procedures with triaxial test set-up.

© IEC 2018
Table 1 – IEC 62153, Metallic communication cable test methods –

Test procedures with triaxial test set-up

Metallic Communication Cable test methods − Electromagnetic compatibility (EMC)

IEC TR 62153-4-1 Ed.3 Introduction to electromagnetic (EMC) screening measurements

IEC 62153-4-3 Ed.2
Surface transfer impedance − Triaxial method

IEC 62153-4-4Ed.2 Shielded screening attenuation, test method for measuring of the screening attenuation
a up to and above 3 GHz
s
IEC 62153-4-7 Shielded screening attenuation test method for measuring the transfer impedance Z and
T
the screening attenuation a or the coupling attenuation a of RF-connectors and

s c
assemblies up to and above 3 GHz, tube in tube method

IEC 62153-4-9 Coupling attenuation of screened balanced cables, triaxial method
IEC 62153-4-10 Shielded screening attenuation test method for measuring the screening effectiveness of
feedtroughs and electromagnetic gaskets double coaxial method
IEC 62153-4-15
Test method for measuring transfer impedance and screening attenuation − or coupling
attenuation with triaxial cell (under consideration)
IEC 62153-4-16 Technical report on the relationship between transfer impedance and screening
attenuation (under consideration)

Usually RF connectors have mechanical dimensions in the longitudinal axis in the range of
20 mm to maximum 50 mm. With the definition of electrical short elements we get cut off or
corner frequencies for the transition between electrically short and long elements of about
1 GHz or higher for usual RF-connectors.
To measure the screening attenuation instead of transfer impedance also in the lower
frequency range, the tube in tube procedure was designed. The electrically length of the RF-
connector is extended by a RF-tightly closed metallic extension tube (tube in tube). See
Figure 2.
Measuring
Connector
tube
under test
Matching resistor
Generator
R = Z
1 1
Receiver
Screening cap
Extension tube
Connecting cable
IEC
Figure 2 – Principle of the test set-up to measure transfer impedance
and screening or coupling attenuation of connectors with tube in tube
The tube in tube test set up is based on the triaxial system according to IEC 62153-4-3 and
IEC 62153-4-4 consisting of the DUT, a solid metallic tube and (optional) a RF-tight extension
tube. The matched device under test, DUT, which is fed by a generator, forms the disturbing
circuit which may also be designated as the inner or the primary circuit. The connecting
cables to the DUT are additionally screened by the tube in tube.

– 12 – IEC 62153-4-7:2015+AMD1:2018 CSV

© IEC 2018
The disturbed circuit, which may also be designated as the outer or the second circuit, is

formed by the outer conductor of the device under test (and the extension tube), connected to

the connecting cable and a solid metallic tube, having the DUT under test in its axis.

5.2 Transfer impedance
The test determines the screening effectiveness of a shielded cable by applying a well-

defined current and voltage to the screen of the cable, the assembly or the device under test

and measuring the induced voltage in secondary circuit in order to determine the surface
transfer impedance. This test measures only the magnetic component of the transfer

impedance. To measure the electrostatic component (the capacitance coupling impedance),

the method described in IEC 62153-4-8 should be used.

The triaxial method of the measurement is in general suitable in the frequency range up to
30 MHz for a 1 m sample length and 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 is
found in Clause 9 of IEC TS 62153-4-1:2014 as well as in IEC 62153-4-3.
5.3 Screening attenuation
The disturbing or primary circuit is the matched cable, assembly or device under test. The
disturbed or secondary circuit consists of the outer conductor (or the outermost layer in the
case of multiscreen cables or devices) of the cable or the assembly or the device under test
and a solid metallic housing, having the device under test in its axis (see Figure 3).
The voltage peaks at the far end of the secondary circuit have to be measured. The near end
of the secondary circuit is short-circuited. For this measurement, a matched receiver is not
necessary. The expected voltage peaks at the far end are not dependent on the input
impedance of the receiver, provided that it is lower than the characteristic impedance of the
secondary circuit. However, it is an advantage to have a low mismatch, for example, by
selecting of housings of sufficient size. A detailed description could be found in Clause 10 of
IEC TS 62153-4-1:2014 as well as in IEC 62153-4-4.
5.4 Coupling attenuation
Balanced cables, connectors, assemblies or devices which are driven in the differential mode
may radiate a small part of the input power, due to irregularities in the symmetry. For
unscreened balanced cables, connectors, assemblies or devices, this radiation is related to
the unbalance attenuation a . For screened balanced cables, connectors or assemblies, the
u
unbalance causes a current in the screen which is then coupled by the transfer impedance
and capacitive coupling impedance into the outer circuit. The radiation is attenuated by the
screen of the component and is related to the screening attenuation a .
s
Consequently the effectiveness against electromagnetic disturbances of shielded balanced
cables, connectors or assemblies is the sum of the unbalance attenuation a of the pair and
u
the screening attenuation a of the screen. Since both quantities usually are given in a
s
logarithmic ratio, they may simply be added to form the coupling attenuation a :
c
a = a +a (8)
c u s
Coupling attenuation a is determined from the logarithmic ratio of the feeding power P and
c 1
(which may be radiated due to the peaks of
the periodic maximum values of the power P
r,max
voltage U in the outer circuit):
 
P
r,max
 
(9)
a = –10 log Env
c 10
 
P
 
© IEC 2018
where
Env is the minimum envelope curve of the measured values in dB.

The relationship of the radiated power P to the measured power P received on the input
r 2
impedance R is:
P P R
s S max
= = (10)
P P 2⋅ Z
2 2max s
There will be a variation of the voltage U on the far end, caused by the electromagnetic
coupling through the screen and superposition of the partial waves caused by the surface
transfer impedance Z ,the capacitive coupling impedance Z (travelling to the far and near
T F
end) and the totally reflected waves from the near end.
To feed the balanced device under test, a differential mode signal is necessary. This can be
achieved with a two-port network analyser (generator and receiver) and a balun or a multiport
network analyser. The procedure to measure coupling attenuation with a multiport network
analyser is under consideration.
6 Test procedure
6.1 General
The measurements shall be carried out at the temperature of (23 ± 3) °C. The test method
determines the transfer impedance or the screening attenuation or the coupling attenuation of
a DUT by measuring in a triaxial test set-up according to IEC 62153-4-3 and IEC 62153-4-4.
6.2 Tube in tube procedure
Usually RF connectors have mechanical dimensions in the longitudinal axis in the range of
20 mm to maximum 50 mm. With the definition of electrically short elements, we get cut off or
corner frequencies or corner for the transition between electrically short and long elements of
about 1 GHz or higher for usual RF-connectors.
In the frequency range up to the cut off frequency, where the device under test (DUT) is
electrically short, the transfer impedance of the DUT can be measured. For frequencies above
the cut-off frequency, where the DUT is electrically long, the screening attenuation can be
measured.
By extending the electrically length of the RF-connector by a RF-tightly closed metallic

extension tube (tube in tube), the tested combination becomes electrically long and the cut-off
frequency is moved towards the lower frequency range. In this way, also in the lower
frequency range, the screening attenuation may be measured and the effective transfer
impedance of electrical short devices calculated.
The test set up is a triaxial system consisting of the DUT, a solid metallic tube and a RF-tight
extension tube. The matched device under test, DUT, which is fed by a generator forms the
disturbing circuit which may also be designated as the inner or the primary circuit.
The disturbed circuit, which may also be designated as the outer or the second circuit, is
formed by the outer conductor of the device under test, connected to the extension tube and a
solid metallic tube having the DUT under test in its axis.
The principle of the test set-up is shown in Figure 2 and Figure 3. The set-up is the same for
measuring the transfer impedance and the screening- or the coupling attenuation, whereas
the length of the inner and the outer tube may vary.

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© IEC 2018
Measuring tube
Connector interface
Assembly
under test Matching resistor
R = Z
1 1
Generator
Receiver
Screening cap
Connecting cable
Extension tube,
variable length
IEC
Figure 3 – Principle of the test set-up to measure transfer impedance
and screening attenuation of a cable assembly
The voltage ratio of the voltage at the near end (U ) of the inner circuit (generator) and the
voltage at the far end (U ) of the secondary circuit (receiver) shall be measured (U /U ). The
2 1 2
near end of the secondary circuit is short-circuited.
Depending on the electrical length of the tested combination, the DUT and the extension tube,
the result may be expressed either by the transfer impedance, the effective transfer
impedance or the screening attenuation (or the coupling attenuation).
For this measurement, a matched receiver is not necessary. The likely voltage peaks at the
far end are not
...