IEC 61196-1-108:2011

Coaxial communication cables - Part 1-108: Electrical test methods - Test for characteristic impedance, phase and group delay, electrical length and propagation velocity

IEC 61196-1-108:2011(E) applies to coaxial communications cables. It specifies test methods for determining the characteristic impedance, phase and group delay, electrical length and propagation velocity of coaxial cables for use in telecommunications networks. This second edition replaces the first edition published in 2005. The main changes to the previous edition is the enclosing of Annex A describing the measurement of phase dispersion.

General Information

• Status: Published
• Publication Date: 28-Nov-2011
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 33.120.10 - Coaxial cables. Waveguides
• Technical Committee: SC 46A - Coaxial cables
• Drafting Committee: WG 3 - TC 46/SC 46A/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 30-Nov-2011
• Completion Date: 29-Nov-2011

Relations

• Revises: IEC 61196-1-108:2005 - Coaxial communication cables - Part 1-108: Electrical test methods - Test for characteristic impedance, phase and group delay, electrical length and propagation velocity
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61196-1-108 ®
Edition 2.0 2011-11
INTERNATIONAL
STANDARD
colour
inside
Coaxial communication cables –
Part 1-108: Electrical test methods – Test for characteristic impedance, phase
and group delay, electrical length and propagation velocity

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IEC 61196-1-108 ®
Edition 2.0 2011-11
INTERNATIONAL
STANDARD
colour
inside
Coaxial communication cables –
Part 1-108: Electrical test methods – Test for characteristic impedance, phase
and group delay, electrical length and propagation velocity

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
N
ICS 33.120.10 ISBN 978-2-88912-786-3

– 2 – 61196-1-108 © IEC:2011(E)
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Parameters . 5
5 Test method . 6
5.1 Equipment . 6
5.2 Test sample . 6
5.3 Procedure . 7
6 Expression of test results . 7
6.1 Phase constant β. 7
6.2 Phase and group delay . 8
6.3 Velocity of propagation . 8
6.4 Electrical length. 8
6.5 Characteristic impedance . 9
7 Test report. 9
8 Requirements . 9
Annex A (normative) Phase dispersion measurement of coaxial cables. 10
Bibliography . 14

Figure 1 – Phase shift expanded . 7
Figure A.1 – Phase dispersion of 1/2" cable with deeply corrugated outer conductor . 13

61196-1-108 © IEC:2011(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COAXIAL COMMUNICATION CABLES –

Part 1-108: Electrical test methods –
Test for characteristic impedance, phase and group delay,
electrical length and propagation velocity

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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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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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 61196-1-108 has been prepared by subcommittee 46A: Coaxial
cables, of IEC technical committee 46: Cables, wires, waveguides, R.F. connectors, R.F. and
microwave passive components and accessories.
This second edition replaces the first edition published in 2005. The main changes to the
previous edition is the enclosing of Annex A describing the measurement of phase dispersion.
The text of this standard is based on the following documents:
FDIS Report on voting
46A/1039/FDIS 46A/1057/RVD
– 4 – 61196-1-108 © IEC:2011(E)

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 standard is intended to be read in conjunction with IEC 61196-1. It is based on the
second edition (2005) of that standard.
A list of all parts of IEC 61196 series, published under the general title Coaxial
communication cables, 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 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.
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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.
A bilingual version of this publication may be issued at a later date.

61196-1-108 © IEC:2011(E) – 5 –
COAXIAL COMMUNICATION CABLES –

Part 1-108: Electrical test methods –
Test for characteristic impedance, phase and group delay,
electrical length and propagation velocity

1 Scope
This part of IEC 61196 applies to coaxial communications cables. It specifies test methods for
determining the characteristic impedance, phase and group delay, electrical length and
propagation velocity of coaxial cables for use in telecommunications networks.
A procedure to measure phase dispersion of coaxial cable is included as Annex A.
2 Normative references
The following referenced documents are indispensable for the application 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 61196-1:2005, Coaxial communication cables – Part 1: Generic specification – General,
definitions and requirements
IEC 61196-1-103, Coaxial communication cables – Part 1-103: Electrical test methods – Test
for capacitance of cable
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61196-1 apply.
4 Parameters
From the phase constant β of a cable, one can derive several parameters:
group delay (1)
dβ ∆β
τ = ≈
g
dω ∆ω
phase delay (2)
β
τ =
p
ω
propagation velocity (3)
1 ω
v = =
τ β
p
relative propagation velocity (4)
v 1 l
mech
v = = =
r
c τ ⋅ c l
p e
electrical length (5)
l = l ⋅τ ⋅ c
e mech p
– 6 – 61196-1-108 © IEC:2011(E)
characteristic impedance (6)
τ
β
p
Z = =
c
ωC C
where
is the phase constant in radian/m;
β
ω = 2 π f is the angular frequency in radian/s;
is the group delay in s/m;
τ
g
is the phase delay in s/m;
τ
p
C is the capacitance in pF/m;
c
is the propagation velocity in free space (3⋅10 m/s);
l is the electrical length in m;

e
l
is the mechanical length in m;

mech
v is the propagation velocity in m/s;
v
is the relative propagation velocity;

r
Z
is the characteristic impedance in Ω.
c
Delay and velocity parameters as well as characteristic impedance are frequency-dependent
and reach an asymptotic value at high frequencies. It is usual to report them at frequencies
higher than 200 MHz where the frequency is sufficiently high for the theoretical approximation
always to be valid. Generally, the above-given formulas are limited to low dispersive cables
as coaxial communications cables typically are in their specified frequency range. Methods
with a wider range of application are given in Annex A.
5 Test method
5.1 Equipment
The equipment to be used consists of:
– a capacitance metre or bridge in accordance with IEC 61196-1-103.
– a vector network analyser (VNA) capable of performing S measurements.
5.2 Test sample
Due to the cyclic behaviour of exp(-jβl), a VNA can measure the phase constant β only in the
range of –180 ° to +180 ° respectively from –π to +π and doesn’t give an information how
many phase turns have already been at the lowest frequency. To avoid hidden phase turns,
the maximum length of the sample should be:
l <
(7)
max
Z ⋅ C ⋅ f
c
where
C is the capacitance of the cable in pF/m according to IEC 61196-1-103;
f is the lowest frequency to be measured in MHz;
l is the maximum possible sample length in m;

max
Z is the nominal characteristic impedance of the cable.
c
This restriction is not applicable if solely group delay is to be measured as then only the
derivative of the phase is important.

61196-1-108 © IEC:2011(E) – 7 –
5.3 Procedure
The S or S parameter of the sample shall be measured with the VNA. The phase constant
21 12
obtained from this measurement is used to
...