SIST EN 60556:2007

SLOVENSKI STANDARD
01-september-2007
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Gyromagnetic materials intended for application at microwave frequencies - Measuring
methods for properties (IEC 60556:2006)
Gyromagnetische Materialien für Mikrowellenanwendungen - Messverfahren zur
Ermittlung der Eigenschaften (IEC 60556:2006)
Materiaux gyromagnétiques destinés aux applications hyperfréquences - Méthodes de
mesure des caractéristiques (IEC 60556:2006)
Ta slovenski standard je istoveten z: EN 60556:2006
ICS:
29.100.10 Magnetne komponente Magnetic components
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 60556
NORME EUROPÉENNE
June 2006
EUROPÄISCHE NORM
ICS 29.100.10
English version
Gyromagnetic materials intended for application
at microwave frequencies -
Measuring methods for properties
(IEC 60556:2006)
Materiaux gyromagnétiques destinés  Gyromagnetische Materialien
aux applications hyperfréquences - für Mikrowellenanwendungen -
Méthodes de mesure des caractéristiques Messverfahren zur Ermittlung
(CEI 60556:2006) der Eigenschaften
(IEC 60556:2006)
This European Standard was approved by CENELEC on 2006-05-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in two official versions (English and German). A version in any other language
made by translation under the responsibility of a CENELEC member into its own language and notified to the
Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60556:2006 E
Foreword
The text of document 51/850/FDIS, future edition 2 of IEC 60556, prepared by IEC TC 51, Magnetic
components and ferrite materials, was submitted to the IEC-CENELEC parallel vote and was approved by
CENELEC as EN 60556 on 2006-05-01.
This Standard is to be used in conjunction with IEC 60392.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2007-02-01
– latest date by which the national standards conflicting
(dow) 2009-05-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60556:2006 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 60556:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

1)
IEC 60050-221 - International electrotechnical vocabulary - - -
Chapter 221: Magnetic materials and
components
IEC 60205 2006 Calculation of the effective parameters of EN 60205 2006
magnetic piece parts
IEC 60392 1972 Guide for the drafting of specifications for - -
microwave ferrites
1)
Undated reference.
INTERNATIONAL IEC
STANDARD 60556
Second edition
2006-04
Gyromagnetic materials intended
for application at microwave frequencies –
Measuring methods for properties

 IEC 2006  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
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International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

– 2 – 60556  IEC:2006(E)
CONTENTS
FOREWORD.5

1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 Saturation magnetization M .7
s
4.1 General .7
4.2 Object .8
4.3 Theory.8
4.4 Test sample .9
4.5 Measuring apparatus for the vibrating coil method (VCM).9
4.6 Measuring apparatus for the vibrating sample method (VSM) .12
4.7 Calibration.15
4.8 Measuring procedure.16
4.9 Calculation .17
4.10 Accuracy .17
4.11 Data presentation.18
5 Magnetization (at specified field strength) M .18
H
5.1 General .18
5.2 Object .18
5.3 Theory.18
5.4 Test specimen.20
5.5 Measuring apparatus.21
5.6 Calibration.23
5.7 Measuring procedure.24
5.8 Calculation .24
5.9 Accuracy .24
5.10 Data presentation.24
6 Gyromagnetic resonance linewidth ΔH and effective Landé factor g (general) .25
eff
6.1 General .25
6.2 Object .25
6.3 Theory.25
6.4 Test specimens and cavities.26
6.5 Measuring apparatus.29
6.6 Measuring procedure.29
6.7 Calculation .31
6.8 Accuracy .31
6.9 Data presentation.31
7 Gyromagnetic resonance linewidth ΔH and effective Landé factor g (at 10 GHz) .31
10 10
7.1 General .31
7.2 Object .31
7.3 Theory.31

60556  IEC:2006(E) – 3 –
7.4 Test specimen and cavity .32
7.5 Measuring apparatus.33
7.6 Measuring procedure.33
7.7 Calculation .34
7.8 Accuracy .34
7.9 Data presentation.35
8 Spin-wave resonance linewidth ΔH .35
k
8.1 General .35
8.2 Object .35
8.3 Theory.35
8.4 Test specimen and cavity .38
8.5 Measuring apparatus.39
8.6 Calibration.39
8.7 Measuring procedure.39
8.8 Calculation .40
8.9 Accuracy .40
8.10 Data presentation.40
9 Effective linewidth ΔH .40
eff
9.1 General .40
9.2 Object .40
9.3 Theory.41
9.4 Test specimen and cavity .43
9.5 Measuring apparatus.43
9.6 Calibration.44
9.7 Apparatus adjustment.44
9.8 Measuring procedure.45
9.9 Calculation .46
9.10 Accuracy .46
9.11 Data presentation.46
10 Complex permittivity ε .47
r
10.1 General .47
10.2 Object .47
10.3 Theory.47
10.4 Test specimen and cavity .50
10.5 Measuring apparatus.50
10.6 Measurement procedure.51
10.7 Calculation .51
10.8 Accuracy .52
10.9 Data presentation.52
11 Apparent density ρ .52
app
11.1 General .52
11.2 Apparent density (by mensuration) .52
11.3 Apparent density (by water densitometry).54

Bibliography.56

– 4 – 60556  IEC:2006(E)
Figure 1 – Vibrating coil method – Sample and coils arrangement .9
Figure 2 – Magnetic field configuration .10
Figure 3 – Measuring apparatus (VCM).12
Figure 4 – Vibrating sample method – Sample and coil arrangement .13
Figure 5 – Measuring apparatus (VSM).14
Figure 6 – Hysteresis curves for a magnetic material: B(H) curve, M(H) curve .19
Figure 7 – Test sample with compensation unit.20
Figure 8 – Test specimen.21
Figure 9 – Measuring circuit for determining magnetization (at specified field strength) M .22
H
Figure 10 – Miller integrator .23
Figure 11 – Cavity for measurement of gyromagnetic resonance linewidth and
effective Landé factor .27
Figure 12 – Stripline resonator for measurement of gyromagnetic resonance linewidth
and effective Landé factor at low frequency .28
Figure 13 – Schematic diagram of the equipment required for measurement of
gyromagnetic resonance linewidth and effective Landé factor .30
Figure 14 – Schematic diagram of the equipment required for measurement of
gyromagnetic resonance linewidth and effective Landé factor at 10 GHz .34
Figure 15 – Subsidiary absorption and saturation of the normal resonance .36
Figure 16 – Pulse deterioration at onset of subsidiary resonance.36
Figure 17 – Measured critical r.f. field strength as a function of pulse duration t .37
d
Figure 18 – Typical TE cavity for the measurement of spin-wave resonance
linewidth at about 9,3 GHz.38
Figure 19 – Block diagram of spin-wave resonance linewidth test equipment .39
Figure 20 – Sectional view of the cavity with specimen .42
Figure 21 – Dimensions of a cavity designed for resonance at a frequency of 9,1 GHz .42
Figure 22 – Schematic diagram of equipment for measuring effective linewidth ΔH .44
eff
Figure 23 – Determination of Q .46
Figure 24 – Ideal resonant cavity with specimen, used for theoretical calculation
(sectional view).48
Figure 25 – Dimensions of the resonant cavity with specimen.50
Figure 26 – Schematic diagram of equipment required for the measurement of
complex dielectric constant.51

60556  IEC:2006(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GYROMAGNETIC MATERIALS
INTENDED FOR APPLICATION AT MICROWAVE FREQUENCIES –
MEASURING METHODS FOR PROPERTIES

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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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 60556 has been prepared by IEC technical committee 51:
Magnetic components and ferrite materials.
This second edition cancels and replaces the first edition, published in 1982, its amendment 1
(1997) and amendment 2 (2004). This edition constitutes a technical revision.
This second edition is a consolidation of the first edition and its amendments 1 and 2.
It includes editorial improvements as well as improvements to the figures.
This standard is to be read in conjunction with IEC 60392.

– 6 – 60556  IEC:2006(E)
The text of this standard is based on the following documents:
FDIS Report on voting
51/850/FDIS 51/859/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.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.

60556  IEC:2006(E) – 7 –
GYROMAGNETIC MATERIALS
INTENDED FOR APPLICATION AT MICROWAVE FREQUENCIES –
MEASURING METHODS FOR PROPERTIES

1 Scope
This International Standard describes methods of measuring the properties used to specify
polycrystalline microwave ferrites in accordance with IEC 60392 and for general use in ferrite
technology. These measuring methods are intended for the investigation of materials,
generally referred to as ferrites, for application at microwave frequencies.
Single crystals and thin films generally fall outside the scope of this standard.
NOTE 1 For the purposes of this standard, the words “ferrite” and “microwave” are used in a broad sense:
– by “ferrites” is meant not only magneto-dielectric chemical components having a spinel crystal structure, but
also materials with garnet and hexagonal structures;
– the “microwave” region is taken to include wavelengths approximately between 1 m and 1 mm, the main interest
being concentrated on the region 0,3 m to 10 mm.
NOTE 2 Examples of components employing microwave ferrites are non-reciprocal devices such as circulators,
isolators and non-reciprocal phase-shifters. These constitute the major field of application, but the materials may
be used in reciprocal devices as well, for example, modulators and (reciprocal) phase-shifters. Other applications
include gyromagnetic filters, limiters and more sophisticated devices, such as parametric amplifiers.
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 amendment) applies.
IEC 60050-221, International Electrotechnical Vocabulary (IEV) – Part 221: Magnetic materials
components
IEC 60205:2006, Calculation of the effective parameters of magnetic piece parts
IEC 60392:1972, Guide for the drafting of specifications for microwave ferrites
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-221 apply.
4 Saturation magnetization M
s
4.1 General
Saturation magnetization is a characteristic parameter of ferrite materials. It is widely used in
theoretical calculations, for instance in computation of tensor permeability components (see
IEC 60050-221). In a variety of microwave applications, saturation magnetization determines
the lower frequency limit of the device, mainly due to the occurrence of so-called low-field
loss when the material is unsaturated.

– 8 – 60556  IEC:2006(E)
4.2 Object
The object is to give two similar techniques for measuring saturation magnetization. These
are the vibrating coil method (VCM) and vibrating sample method (VSM).
The vibrating coil method [1] [2] has the advantages of easier sample mounting and simpler
mechanical arrangement when measurements over a range of temperatures are required,
particularly at low temperatures.
The vibrating sample method is more accurate, given a similar degree of elaboration in
electronic apparatus.
The equipment needed in both cases is very similar and the calibration methods are identical.
The same test samples can be used for either technique.
4.3 Theory
When a sphere of isotropic magnetic material is placed in a uniform magnetic field, the sphere
becomes uniformly magnetized in the direction parallel to the applied field. The sphere now
produces its own external magnetic field, equivalent to that of a magnetic dipole at the centre
of the sphere and orientated parallel to the direction of magnetization.
If a small detection coil (in practice a pair wound in opposition) is now vibrated at small
amplitude, close to the sample sphere and in a direction at right angles to the applied field, a
voltage e , will be induced in the coil, proportional to the rate of change of flux ϕ due to the
s s
sample at the mean coil position x whose value is given by
dϕ dx
 
s
e = −N ⋅ ⋅ (1)
 
s
dx dt
 
x
where N is the number of turns on the coil.
The motion of the coil, in the x-direction, is given by
x = x + δ sin ωt (2)
where
x is displacement at time t;
ω is angular frequency;
δ is vibration amplitude.
If the unknown sample is now replaced by a calibrating sample of known saturation
magnetization M and volume V , inducing a voltage e , the magnetization of the sample M
c c c s
may be found by comparison:
M e V
s s c
= ⋅ (3)
M e V
c c s
If the induced voltages e and e give rise to readings E and E from the apparatus, then
s c s c
E d
s c
M = M ⋅ ⋅ (4)
s c
E d
c s
and d are diameters of the sample and calibrating spheres, respectively.
where d
s c
—————————
Figures in square brackets refer to the bibliography.

60556  IEC:2006(E) – 9 –
Identical equations apply in the VSM case, when the sample is vibrated while the coil remains
stationary.
4.4 Test sample
For the dipole assumption to be valid, the test sample shall be a sphere, whose deviation from
roundness is not more than 0,5 %. The percentage deviation from roundness is defined as
 max. diameter − min. diameter
× 100 (5)
 
min. diameter
 
For most ferrite materials, a diameter of about 2,5 mm is suitable. If it is less than 1 mm, a
reasonable signal-to-noise ratio will be difficult to achieve, particularly when M is low.
s
Spheres larger than about 4 mm are less convenient to make and it is not so easy to maintain
a uniform applied field over the volume of the sphere.
It may be permissible to use other than spherical samples, provided that the induced voltage
can be shown to be a linear function of the magnetization to within the accuracy required, and
that the calibration sample has identical dimensions to the samples to be measured.
4.5 Measuring apparatus for the vibrating coil method (VCM)
4.5.1 Arrangement of detection coils and sample
A schematic diagram of the arrangement of the detection coils and the sample is shown in
Figure 1. Figure 2 indicates the directions of the applied and sample fields.
The sample is rigidly mounted between the pole-pieces of an electromagnet, in such a way
that its position relative to the detection coils is reproducible to ±0,1 mm in any direction. All
parts of the sample holder shall be made of non-magnetic material.
The detection coils are an identical pair wound in series opposition. They are attached to the
vibrator by a rigid, non-magnetic arm and are located as close to the sample as practicable.
Their axes are normally parallel to the direction of vibration, but other configurations are
acceptable.
Vibration
x
Electromagnet pole
Electromagnet pole
z
Sample
y
Detection coils
IEC  555/06
Figure 1 – Vibrating coil method – Sample and coils arrangement

– 10 – 60556  IEC:2006(E)
Applied magnetic field
Electromagnet pole
Electromagnet pole
x
z
Dipole field of sample
y
IEC  556/06
Figure 2 – Magnetic field configuration
The direction of vibration (the x-direction) is at 90° to the z-axis of the electromagnet (Figure
1), i.e. perpendicular to the magnetostatic field direction, and the amplitude shall be of the
order of 0,05 mm to 0,5 mm. The frequency is not critical, but would normally be between
20 Hz and 200 Hz, although frequencies outside that range are acceptable. Motion of the coils
in the z- and y-directions shall be limited by means of suitable mounting to not more than 1 %
of that in the x-direction. Some means of stabilizing the vibration amplitude by use of a
feedback loop may be incorporated if required.
4.5.2 The electromagnet
The magnetostatic field shall be capable of fully saturating a spherical specimen of the
–1
material to be measured. For most microwave ferrites, a field of 300 kAm will be adequate,
–1
but for the hexagonal, barium-based ferrites, a field up to 500 kAm may be needed. The
current supply to the electromagnet shall be such as to maintain the field stable to 0,5 %.
At the mean position of the detection coils, the transverse field shall be not more than 1 % of
the longitudinal field (H ).
z
Since the uniformity of the field is dependent on the field-strength, measurements shall
always be made at the applied field at which calibration and zero-setting (see 4.8) have been
carried out.
4.5.3 Elimination of applied field effects
If the applied field were wholly uniform and had no radial components, while the direction of
vibration was exactly at right angles to the applied field, the theory of 4.3 could be applied
directly to the experimental arrangement of Figure 1.
However, as indicated in Figure 2, the applied field is not uniform, and its direction and
magnitude vary from point to point. Moreover, it is impracticable to make an identical pair of
detection coils. The angle of vibration will deviate from 90° and some residual motion in the y-
and z-directions will always be present.
Voltages will therefore be induced in the coils by the inhomogeneity of the applied field. The
effect of H is considerably lessened by winding the coils in opposition, so that voltages due
z
to H tend to cancel out whereas those due to the sample dipole field will add up.
z
However, complete cancellation cannot in general be achieved with one pair of coils alone.
Therefore, a second pair of coils, the compensating coils, is used. These are mounted on the
same formers as the sample coils, but are wound in series, so that the voltages induced by H
z
are additive. A compensating voltage can then be obtained, which may be adjusted in
amplitude and phase to balance out the voltage induced in the sample coils by H .
z
60556  IEC:2006(E) – 11 –
The effect of H is more difficult to eliminate because the voltages induced in the sample coils
x
will be added in the same way as those due to the dipole field. However, in general, the
variation of H with x will be different from that of the sample dipole field. The two signals will
x
therefore differ in phase and may be distinguished by means of a phase sensitive detector.
4.5.4 Electronic instrumentation
A schematic diagram of the measuring apparatus is shown in Figure 3. The vibrator is driven
by a low-frequency oscillator (9), which may be tunable, and a power amplifier. The amplitude
of the oscillator output and the gain of the power amplifier shall be sufficiently stable to
provide a constant drive to the vibrator to within ±0,3 %, after warm-up. If this is not possible,
some means of stabilizing the vibration amplitude shall be provided. The oscillator frequency
shall be stable to 0,05 % after warm-up.
The output from the compensating coils (1(c)) is balanced against that of the sample coils
(1(s)) by means of the difference amplifier (4), using the variable attenuator (2) and phase
shifter (3). The phase shifter shall be fully variable over 360° and its resolution shall be at
least ±0,1°. Neither the phase shifter nor the attenuator needs to be calibrated.
The difference amplifier shall have a low enough noise level at low frequencies to allow
precise zero setting. The exact requirements will depend on the design of the coils and other
equipment. A variable gain control may be incorporated.
The low-pass filter (5) shall reduce all harmonics by at least 20 dB with respect to the
fundamental frequency.
The selective amplifier, which is tuned to the oscillator frequency, shall have a bandwidth of
the order of 1 % and shall be tunable if the oscillator is not tunable.
The phase-sensitive detector (7) shall have a resolution better than 3° and either the
reference or signal channel shall be variable over 360° in phase. The phase setting shall be
independent of the amplitude of the input to either channel.
The meter (8) may be an analogue or digital type. When measurements are to be made over a
range of temperatures, an X–Y-recorder may be substituted for the meter, one axis to record
a linear function of magnetization, the other a linear function of temperature. Both axes shall
be calibrated to the accuracy required. The temperature measuring device, normally a
thermocouple, shall be in close thermal contact with the sample itself.
All the electronic instruments shall have adequate temperature stability to ensure the required
accuracy over the range of ambient temperatures to be met in use.

– 12 – 60556  IEC:2006(E)
Sample
coils
Selective
1(s)
low-frequency
Phase-sensitive
amplifier
detector
Difference
4 5 7
amplifier
Compensating
coils
Meter or
Low-pass
filter digital voltmeter
1(c)
Attenuator Phase shifter
Oscilloscope
Low-frequency
oscillator
Power
amplifier
Vibrator
IEC  557/06
Figure 3 – Measuring apparatus (VCM)
4.6 Measuring apparatus for the vibrating sample method (VSM)
4.6.1 Arrangement of detection coils and sample
In the vibrating sample case, the detection coils (Figure 4) are rigidly mounted between the
pole-pieces of the electromagnet, but in such a way that frequent small adjustments are
possible. Normally, their axes are at right angles to the applied field and parallel to the
direction of vibration, but other configurations [5] are acceptable. The mean sample position
is on the axis of the electromagnet, normally located symmetrically with respect to the
detection coils. Its position shall be reproducible to ±0,1 mm. It is rigidly mounted on a non-
magnetic vibrating arm, attached to a vibrator, and is as close to the detection coils as
practicable.
The direction of vibration (the x-direction) is at 90° to the z-axis of the electromagnet
(Figure 4), i.e. perpendicular to the magnetostatic field direction, and the amplitude shall be of
the order of 0,05 mm to 0,5 mm. The frequency is not critical, but would normally be between
20 Hz and 200 Hz, although frequencies outside that range are acceptable. Motion of the
sample in the z- and y-directions shall be limited by means of a suitable mounting to not more
than 1 % of that in the x-direction. Some means of stabilizing the vibration amplitude by use of
a feedback loop may be incorporated if necessary.
A small permanent magnet is attached to the vibrating arm, far enough away from the
electromagnet to be unaffected by it. Two small coils are mounted rigidly on either side of this
magnet to detect its field. A small coil carrying a precisely controlled direct current may be
used instead of the magnet.
60556  IEC:2006(E) – 13 –
Permanent magnet or d.c. coil
Balancing coils
Vibration
Electromagnet pole x
Electromagnet pole
z
Detection coils
y
Sample
IEC  558/06
Figure 4 – Vibrating sample method – Sample and coil arrangement
4.6.2 The electromagnet
No precautions need be taken to counteract curvature and non-uniformity of applied field,
provided that a uniformity of about 3 % over the volume of the sample is maintained. A radial
field of up to 1 % of the longitudinal field is permissible.
The magnetostatic field shall be capable of fully saturating a spherical specimen of the
–1
material to be measured. For most microwave ferrites, a field of 300 kAm will be adequate,
–1
but for the hexagonal, barium-based ferrites a field up to 500 kAm may be needed. The
current supply shall maintain the field stable to about 0,5 %.
4.6.3 Electronic instrumentation
A schematic diagram of the electronic instrumentation is shown in Figure 5. The simplest
arrangement uses only items 1 to 8, and allows point-by-point measurements to be made at
fixed temperatures. The calibrated potential divider (3) is used to balance the voltage induced
in the balancing coils against that in the sample coils. The null point is observed by means of
the oscilloscope (5). Magnetization is calculated from the potential divider setting.
Alternatively, the null balance may be made with the empty sample holder in position. The
out-of-balance signal on insertion of a sample is then proportional to magnetization. This
signal may be read directly from the meter (5) or oscilloscope. For continuous plotting of M
s
as a function of temperature, an X–Y-recorder may be substituted for the oscilloscope.
Greater sensitivity and better stability may be obtained by use of a phase sensitive detector (9)
to detect the signal, which may then be observed by means of a meter or recorder.
If a d.c. coil (12) is used instead of a permanent magnet to obtain the balancing voltage,
automatic null balancing may be achieved by feeding the output of this phase sensitive
detector to the d.c. coil. The current in the coil is then directly proportional to magnetization.
The coil current may be measured by means of a d.c. ammeter in series with it, or by a high-
resistance voltmeter in parallel with the coil. In the second case, variations in coil resistance
due to temperature changes shall be compatible with the degree of accuracy required in M .
s
– 14 – 60556  IEC:2006(E)
Sample
coils
1(s)
Difference
Oscilloscope
amplifier
4 5
or meter
(selective)
Balancing
coils
1(b)
Potential
Phase shifter
divider
Meter or
digital voltmeter
Phase-sensitive
detector
Low-frequency
Power
oscillator
amplifier
DC voltmeter
Ammeter
Vibrator
DC coil
Buffer
amplifier
IEC  559/06
Figure 5 – Measuring apparatus (VSM)
The vibrator is driven by a low-frequency oscillator, which may be tunable, and a power
amplifier. The amplitude of the oscillator output and the gain of the power amplifier shall be
sufficiently stable to maintain the drive to the vibrator at a constant level, to within 0,3 % after
warm-up. If this is not possible, some means of stabilizing the vibration amplitude shall be
provided. The oscillator frequency shall be stable to within 0,05 % after warm-up.
The potential divider shall be continuously variable with a resolution of 0,01 % or better and
shall be calibrated to the accuracy required.
The difference amplifier shall have a sufficiently low noise level and shall incorporate, or be
followed by, a selective amplifier with a bandwidth of the order of 3 %, tuned to the oscillator
frequency. The selective stage shall be tunable if the oscillator is not tunable.
The requirements for the phase-sensitive detector are not stringent. A resolution of 10° is
adequate. The phase setting shall be independent of the amplitude of the input to either
channel.
The meters may be analogue or digital types. When measurements are to be made over a
range of temperatures, an X–Y-recorder may be substituted for the meter, one axis to be a
linear function of magnetization, the other a linear function of temperature. Both shall be
calibrated to the accuracy required. The temperature measuring device, normally a
thermocouple, shall be in close thermal contact with the sample itself.
All the electronic equipment shall have adequate temperature stability to maintain the
required accuracy over the range of ambient temperatures generally encountered in use.

60556  IEC:2006(E) – 15 –
4.7 Calibration
4.7.1 Comparison method
This method, which is equally applicable to either the vibrating coil or the vibrating sample
methods, calls for a standard sample whose saturation magnetization is accurately known.
The most usual material for the standard is pure nickel, but other materials may be used if
their saturation magnetization is known accurately enough.
The calibration sample shall be a sphere (if the samples to be measured are spheres) and be
of a similar order of size. (If samples other than spheres have to be measured,
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