IEC 62037-1:2021

Passive RF and microwave devices, intermodulation level measurement - Part 1: General requirements and measuring methods

IEC 62037-1:2021 is available as IEC 62037-1:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 62037-1:2021 deals with the general requirements and measuring methods for intermodulation (IM) level measurement of passive RF and microwave components, which can be caused by the presence of two or more transmitting signals. The test procedures given in this document give the general requirements and measurement methods required to characterize the level of unwanted IM signals using two transmitting signals. The IEC 62037 series addresses the measurement of PIM, but does not cover the long-term reliability of a product with reference to its performance. This second edition cancels and replaces the first edition published in 2012. This edition includes the following significant technical changes with respect to the previous edition:
a. clarification added that test equipment may utilize pulsed generators to reduce power consumption;
b. heating effect differences in the device under test noted in Annex B for tests conducted using pulsed generators;
c. guidance added in Annex B to improve probability of detection of short duration PIM events while dynamic testing.

Dispositifs RF et à micro-ondes passifs, mesure du niveau d'intermodulation - Partie 1: Exigences générales et méthodes de mesure

IEC 62037-1:2021 est disponible sous forme de IEC 62037-1:2021 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L'IEC 62037-1:2021 est applicable aux exigences générales et aux méthodes de mesure du niveau d’intermodulation (IM) des composants RF et à micro-ondes passifs, qui peut être provoquée par la présence de deux ou plusieurs signaux d’émission. Les procédures d’essai présentées dans le présent document donnent les exigences générales et les méthodes de mesure exigées pour caractériser le niveau des signaux d’intermodulation indésirables à l’aide de deux signaux d’émission. La série IEC 62037 porte sur la mesure de l’intermodulation passive (PIM), mais ne couvre pas la fiabilité à long terme des produits par rapport à ses performances. Cette seconde édition annule et remplace la première édition parue en 2012. Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
a. ajout d’une clarification au fait que le matériel d’essai peut utiliser des générateurs à impulsions pour réduire la consommation de puissance;
b. description des différences d’effet de chauffage sur le dispositif en essai à l’Annexe B dans les essais réalisés avec des générateurs à impulsions;
c. ajout de recommandations à l’Annexe B pour améliorer la probabilité de détection d’événements d’intermodulation passive de courte durée lors des essais dynamiques.

General Information

• Status: Published
• Publication Date: 18-Nov-2021
• ICS: 33.040.20 - Transmission systems
• Technical Committee: TC 46 - Cables, wires, waveguides, RF connectors, RF and microwave passive components and accessories
• Current Stage: PPUB - Publication issued
• Completion Date: 19-Nov-2021

Standards Content (sample)

IEC 62037-1
Edition 2.0 2021-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Passive RF and microwave devices, intermodulation level measurement –
Part 1: General requirements and measuring methods
Dispositifs RF et à micro-ondes passifs, mesure du niveau d’intermodulation –
Partie 1: Exigences générales et méthodes de mesure
IEC 62037-1:2021-11(en-fr)
---------------------- Page: 1 ----------------------
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IEC 62037-1
Edition 2.0 2021-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Passive RF and microwave devices, intermodulation level measurement –
Part 1: General requirements and measuring methods
Dispositifs RF et à micro-ondes passifs, mesure du niveau d’intermodulation –
Partie 1: Exigences générales et méthodes de mesure
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.040.20 ISBN 978-2-8322-1050-8

Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 62037-1:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 3

1 Scope .............................................................................................................................. 5

2 Normative references ...................................................................................................... 5

3 Terms, definitions and abbreviated terms ........................................................................ 5

3.1 Terms and definitions .............................................................................................. 5

3.2 Abbreviated terms ................................................................................................... 5

4 Characteristics of intermodulation products ..................................................................... 6

5 Principle of test procedure .............................................................................................. 6

6 Test set-up ...................................................................................................................... 6

6.1 General ................................................................................................................... 6

6.2 Test equipment ....................................................................................................... 7

6.2.1 General ........................................................................................................... 7

6.2.2 Set-up 1 .......................................................................................................... 7

6.2.3 Set-up 2 .......................................................................................................... 8

7 Preparation of DUT and test equipment ............................................................................ 8

7.1 General ................................................................................................................... 8

7.2 Guidelines for minimizing generation of passive intermodulation ............................. 8

8 Test procedure ................................................................................................................ 9

9 Reporting....................................................................................................................... 10

9.1 Results ................................................................................................................. 10

9.2 Example of results ................................................................................................ 10

10 Measurement error ........................................................................................................ 10

Annex A (informative) Configuration of low-PIM termination ................................................ 13

A.1 General ................................................................................................................. 13

A.2 Configuration of low-PIM terminations ................................................................... 13

A.2.1 Long cable termination .................................................................................. 13

A.2.2 Lumped termination with a linear attenuator .................................................. 13

Annex B (informative) Test procedure considerations .......................................................... 15

B.1 PIM variation versus frequency ............................................................................. 15

B.2 Stepped frequency sweep method ........................................................................ 15

B.3 Fixed frequency method ........................................................................................ 15

B.4 Dynamic PIM testing ............................................................................................. 15

B.5 Heating effects ...................................................................................................... 15

Figure 1 – Set-up 1: reverse IM-test set-up .......................................................................... 11

Figure 2 – Set-up 2: forward IM-test set-up .......................................................................... 11

Figure 3 – Passive intermodulation (PIM) measurement error caused by residual

system error ......................................................................................................................... 12

Figure A.1 – Long cable termination ...................................................................................... 13

Figure A.2 – Lumped termination with a linear attenuator ...................................................... 14

Table 1 – Guide for the design, selection of materials and handling of components that

can be susceptible to PIM generation ....................................................................................... 9

Table 2 – Test set-up conditions ........................................................................................... 10

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IEC 62037-1:2021 © IEC 2021 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PASSIVE RF AND MICROWAVE DEVICES,
INTERMODULATION LEVEL MEASUREMENT –
Part 1: General requirements and measuring methods
FOREWORD

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rights. IEC shall not be held responsible for identifying any or all such patent rights.

IEC 62037-1 has been prepared by IEC technical committee 46: Cables, wires, waveguides, RF

connectors, RF and microwave passive components and accessories. It is an International

Standard.

This second edition cancels and replaces the first edition published in 2012. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

a) clarification added that test equipment may utilize pulsed generators to reduce power

consumption;

b) heating effect differences in the device under test noted in Annex B for tests conducted

using pulsed generators;

c) guidance added in Annex B to improve probability of detection of short duration PIM events

while dynamic testing.
---------------------- Page: 5 ----------------------
– 4 – IEC 62037-1:2021 © IEC 2021
The text of this International Standard is based on the following documents:
Draft Report on voting
46/834/FDIS 46/855/RVD

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are

described in greater detail at www.iec.ch/standardsdev/publications.

This International Standard is to be used in conjunction with IEC 62037 (all parts).

A list of all the parts in the IEC 62037 series, published under the general title Passive RF and

microwave devices, intermodulation level measurement, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under webstore.iec.ch in the data related to the

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The "colour inside" logo on the cover page of this document indicates

that it contains colours which are considered to be useful for the correct understanding

of its contents. Users should therefore print this document using a colour printer.

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IEC 62037-1:2021 © IEC 2021 – 5 –
PASSIVE RF AND MICROWAVE DEVICES,
INTERMODULATION LEVEL MEASUREMENT –
Part 1: General requirements and measuring methods
1 Scope

This part of IEC 62037 deals with the general requirements and measuring methods for

intermodulation (IM) level measurement of passive RF and microwave components, which can

be caused by the presence of two or more transmitting signals.

The test procedures given in this document give the general requirements and measurement

methods required to characterize the level of unwanted IM signals using two transmitting signals.

The IEC 62037 series addresses the measurement of PIM, but does not cover the long-term

reliability of a product with reference to its performance.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies.

For undated references, the latest edition of the referenced document (including any

amendments) applies.

IEC 62037 (all parts), Passive RF and microwave devices, intermodulation level measurement

3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.2 Abbreviated terms
CATV Community antenna television
CFEC Carbon fibre epoxy composite
CW Continuous wave
DUT Device under test
IM Intermodulation
PCB Printed circuit board
PIM Passive intermodulation
RBW Resolution bandwidth
VDA Vacuum deposited aluminium
---------------------- Page: 7 ----------------------
– 6 – IEC 62037-1:2021 © IEC 2021
4 Characteristics of intermodulation products

PIM interference is caused by sources of non-linearity of mostly unknown nature, location and

behaviour. A few examples are inter-metallic contacts, choice of materials, corrosion products,

dirt, etc. Most of these effects are subject to changes over time due to mechanical stress,

temperature changes, variations in material characteristics (cold flow, etc.) and climatic

changes.

The generation of intermodulation products originates from point sources inside a DUT and

propagates equally in all available directions.

The generation of passive intermodulation (PIM) products does not necessarily follow the law

of the usual non-linear equation of quadratic form. Therefore, accurate calculation to other

power levels causing the intermodulation is not possible and PIM comparisons should be made

at the same power level.

Furthermore, PIM generation can be frequency dependent. When PIM generation is frequency

dependent, the PIM performance shall be investigated over the specified frequency band.

5 Principle of test procedure

Test signals of frequencies f and f with equal specified test port power levels are combined

1 2

and fed to the DUT. The test signals should contain a harmonic or self-intermodulation signal

level at least 10 dB lower than the expected level generated in the DUT.

The PIM is measured over the specified frequency range. The intermodulation products of order

(2f ± f ), (2f ± f ), etc., are measured.
1 2 2 1

In most cases, the third order intermodulation signals represent the worst-case condition of

unwanted signals generated; therefore, the measurement of these signals characterizes the

DUT in a sufficient way. However, the test set-ups given in Clause 6 are suitable for measuring

other intermodulation products.

In other systems (such as CATV), the third order may not be as applicable in characterizing the

DUT.

Intermodulation can be measured in the reverse and forward direction. Reverse and forward

refer to the direction of propagation of the most powerful carrier.
6 Test set-up
6.1 General

Experience shows that the generation of intermodulation products originates from point sources

inside a device under test (DUT) and propagates equally in all available directions. Therefore,

either the reverse (reflected) or the forward (transmitted) intermodulation signal can be

measured.

Two different test set-ups are described in Figure 1 and Figure 2 and are for reference only.

Other topologies are possible.

Set-up 1 is for measuring the reverse (reflected) intermodulation signal only, and set-up 2 is for

measuring the forward (transmitted) intermodulation signal. The measurement method (reverse

or forward) is dependent upon the DUT. The set-ups may be assembled from standard

microwave or radio link hardware selected for this particular application. All components shall

be checked for lowest self-intermodulation generation.
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IEC 62037-1:2021 © IEC 2021 – 7 –

Experience shows that devices containing magnetic materials (circulators, isolators, etc.) can

be prominent sources of intermodulation signal generation.
See Annex B for additional set-up considerations.
6.2 Test equipment
6.2.1 General

Two signal sources or signal generators with power amplifiers are required to reach the

specified test port power. The combining and diplexing device can comprise a circulator, hybrid

junction, coupler or filter network.

The test set-up self-intermodulation generated (including contribution of the load) should be at

least 10 dB below the level to be measured on the DUT. The associated error may be obtained

from the graph in Figure 3.

The DUT shall be terminated by a load for the specified power if necessary. The receiving

bandpass filter, tuned for the desired intermodulation signal, is followed by a low noise amplifier

(if required) and a receiver.
See Annex B for additional set-up considerations.
6.2.2 Set-up 1

This set-up is for measuring the reverse (reflected) IM-product and is therefore suitable for one-

port and multi-port DUTs. On multi-port DUTs, the unused ports shall be connected to a linear

termination. See Annex A for information on low PIM terminations.
a) Generators

The generators shall provide continuous wave (CW) signals of the specified test port power.

They shall have sufficient frequency stability to ensure that the IM-product can be detected

properly by the receiver. The generators may be pulsed on and off while testing to reduce

power consumption.

Some limitations apply when using pulsed generators. See Annex B for test procedure

considerations when using equipment with pulsed generators.
b) Transmit-filters

The filters are bandpass filters tuned to the particular frequencies. They isolate the

generators from each other and filter out the harmonics of f and f .
1 2
c) Combining and diplexing device

This device is used for combining the signals f and f , delivering them to the test port and

1 2
provides a port for the extraction of the reverse (reflected) signal f .
d) Receive-filter

This filter is used for isolating the input of the receiver from the signals f and f to the extent

1 2
that IM-products are not generated within the receiver.
e) Test port

The DUT is connected to P4. The specified input power shall be at the DUT, with any set-

up loss between the receiver and the DUT compensated for.
f) Termination

When a multi-port DUT is measured, the DUT shall be connected to a sufficiently linear

termination (low intermodulation) of suitable power handling capability.
---------------------- Page: 9 ----------------------
– 8 – IEC 62037-1:2021 © IEC 2021
g) Receiver

The receiver shall be sensitive enough to detect a signal of the expected power level.

The receiver response time shall be sufficiently short to allow acquisition of rapid changes

in amplitude. Sensitivity can be increased by a low noise preamplifier. Frequency stability

shall be sufficient for the proper detection of the IM-signal.

When the PIM measurement result is close to the thermal noise floor of the receiver, the

receiver sensitivity can be improved by reducing the resolution bandwidth (RBW).

Furthermore, by using the averaging mode rather than the max-hold mode, a further

improvement can be achieved, since the max-hold mode essentially measures the maximum

thermal noise peak, while the averaging mode results in a measurement that is closer to the

RMS value.
6.2.3 Set-up 2

This set-up is for measuring the forward (transmitted) IM-product and is therefore suitable only

for two- or multi-port DUTs.

All components are the same as those of set-up 1, except for those as noted below:

a) Combining and diplexing device

The extraction-port P3 on this device shall be terminated to prevent reflection of the IM-

signals.
b) Diplexing device

The signals f , f and f are split to P6 and P7. This device, together with an additional

1 2 IM
receive-filter, is used for the extraction of the intermodulation signals.
7 Preparation of DUT and test equipment
7.1 General

The DUT and test equipment shall be carefully checked for proper power handling range,

frequency range, cleanliness and correct interconnection dimensions. All connector interfaces

shall be tightened to the applicable IEC specification or, if none exists, to the manufacturer’s

recommended specification.
See Annex B for additional set-up considerations.
7.2 Guidelines for minimizing generation of passive intermodulation

The following guidelines and Table 1 should be considered and adhered to wherever possible.

a) Non-linear materials should not be used in or near the current paths.

b) Current densities should be minimized in the conduction paths (e.g. Tx channel), by using

larger conductors.
c) Minimize metallic junctions, avoid loose contacts and rotating joints.

d) Minimize the exposure of loose contacts, rough surfaces and sharp edges to RF power.

e) Keep thermal variations to a minimum, as the expansion and contraction of metals can create

non-linear contacts.

f) Use brazed, soldered or welded joints if possible, but ensure these joints are good and have

no non-linear materials, cracks, contamination or corrosion.

g) Avoid having tuning screws or moving parts in the high current paths; if necessary, ensure

all joints are tight and clean, and preferably, free from vibration.

h) Cable lengths in general should be minimized and the use of high quality, low-IM cable is

essential.
---------------------- Page: 10 ----------------------
IEC 62037-1:2021 © IEC 2021 – 9 –

i) Minimize the use of non-linear components such as high-PIM loads, circulators, isolators and

semiconductor devices.

j) Achieve good isolation between the high-power transmit signals and the low power receive

signals by filtering and physical separation.
Table 1 – Guide for the design, selection of materials and handling
of components that can be susceptible to PIM generation
Part, material or procedure Recommendations
Interfaces Minimize the total number.
Connectors Minimize the number of connectors used. Use high quality, low-PIM
connectors mated with proper torque.

Inter-metallic connections Each inter-metallic connection should be evaluated in terms of

criticality for the total PIM level. Methods of controlling the
performance are high contact pressure, insulation, soldering,
brazing, etc.
Ferromagnetic materials Not recommended (non-linear).
Non-magnetic stainless steel Not recommended (contains iron).
Circulators, isolators and other ferrite
Not recommended.
devices
Sharp edges Avoid if it results in high current density.
Terminations or attenuators Should be evaluated before use.
Hermetic seals / gaskets Evaluate before use and avoid ferromagnetic materials.
Materials, processes and design should all be considered and
Printed circuit boards (PCBs)
evaluated. Use low-PIM materials; be careful with material
impurities, contamination and etching residuals. The copper trace
should be finished to prevent corrosion.
Dissimilar metals Not recommended (risk of galvanic corrosion).
Dielectric material Use clean, high quality material. Ensure it does not contain
electrically conductive particles.
Machined dielectric materials Use clean non-contaminated tools for machining.

Welded, soldered or brazed joints Well executed and thoroughly cleaned, they provide satisfactory

results. Shall be carefully inspected.

Carbon fibre epoxy composite (CFEC) Generally acceptable for use in reflector and support structures,

provided the fibres are not damaged. Should be evaluated if high
flux density (e.g. > 10 mW /cm ) is expected.
Standard multilayer
...