Gyromagnetic materials intended for application at microwave frequencies - Measuring methods for properties

Gyromagnetische Materialien für Mikrowellenanwendungen - Messverfahren zur Ermittlung der Eigenschaften

Matériaux gyromagnétiques destinés à des applications hyperfréquences - Méthodes de mesure des propriétés

Giromagnetne snovi za uporabo pri mikrovalovnih frekvencah - Merilne metode za določene lastnosti - Dopolnilo A1

Ta mednarodni standard opisuje metode za merjenje lastnosti, ki se uporabljajo za določitev polikristalnih mikrovalovnih feritov v skladu s standardom IEC 60392 in za splošno uporabo v tehnologiji feritov. Te merilne metode so namenjene za preiskave materialov, ki se običajno imenujejo feriti, za uporabo pri mikrovalovnih frekvencah.

General Information

Status
Published
Publication Date
09-Jun-2016
Current Stage
6060 - Document made available
Due Date
10-Jun-2016
Completion Date
10-Jun-2016

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SLOVENSKI STANDARD
SIST EN 60556:2007/A1:2017
01-april-2017
*LURPDJQHWQHVQRYL]DXSRUDERSULPLNURYDORYQLKIUHNYHQFDK0HULOQHPHWRGH]D
GRORþHQHODVWQRVWL'RSROQLOR$

Gyromagnetic materials intended for application at microwave frequencies Measuring

methods for properties

Matériaux gyromagnétiques destinés à des applications hyperfréquences - Méthodes de

mesure des propriétés
Ta slovenski standard je istoveten z: EN 60556:2006/A1:2016
ICS:
29.100.10 Magnetne komponente Magnetic components
SIST EN 60556:2007/A1:2017 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 60556:2007/A1:2017
---------------------- Page: 2 ----------------------
SIST EN 60556:2007/A1:2017
EUROPEAN STANDARD EN 60556:2006/A1
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2016
ICS 29.100.10
English Version
Gyromagnetic materials intended for application at microwave
frequencies - Measuring methods for properties
(IEC 60556:2006/A1:2016)

Matériaux gyromagnétiques destinés à des applications Gyromagnetische Materialien für Mikrowellenanwendungen -

hyperfréquences - Méthodes de mesure des propriétés Messverfahren zur Ermittlung der Eigenschaften

(IEC 60556:2006/A1:2016) (IEC 60556:2006/A1:2016)

This amendment A1 modifies the European Standard EN 60556:2006; it was approved by CENELEC on 2016-05-05. CENELEC members

are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this amendment 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 CEN-CENELEC

Management Centre or to any CENELEC member.

This amendment exists in three official versions (English, French, 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 CEN-CENELEC Management Centre has the same status as

the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 60556:2006/A1:2016 E
---------------------- Page: 3 ----------------------
SIST EN 60556:2007/A1:2017
EN 60556:2006/A1:2016
European foreword

The text of document 51/1064/CDV, future IEC 60556:2006/A1, prepared by IEC/TC 51 "Magnetic

components and ferrite materials" was submitted to the IEC-CENELEC parallel vote and approved by

CENELEC as EN 60556:2006/A1:2016.
The following dates are fixed:
(dop) 2017-02-05
• latest date by which the document has to be implemented at
national level by publication of an identical national
standard or by endorsement
(dow) 2019-05-05
• latest date by which the national standards conflicting with
the document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such

patent rights.
Endorsement notice

The text of the International Standard IEC 60556:2006/A1:2016 was approved by CENELEC as a

European Standard without any modification.
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SIST EN 60556:2007/A1:2017
IEC 60556
Edition 2.0 2016-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
AM ENDMENT 1
AM ENDEMENT 1
Gyromagnetic materials intended for application at microwave frequencies –
Measuring methods for properties
Matériaux gyromagnétiques destinés à des applications hyperfréquences –
Méthodes de mesure des propriétés
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.100.10 ISBN 978-2-8322-3274-3

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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 5 ----------------------
SIST EN 60556:2007/A1:2017
– 2 – IEC 60556:2006/AMD1:2016
© IEC 2016
FOREWORD

This amendment has been prepared by IEC technical committee 51: Magnetic components

and ferrite materials.
The text of this amendment is based on the following documents:
CDV Report on voting
51/1064/CDV 51/1089A/RVC

Full information on the voting for the approval of this amendment can be found in the report

on voting indicated in the above table.

The committee has decided that the contents of this amendment and the base 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.

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.
_____________
Add, after Clause 11, the following new Clause 12 and Annex A:
12 Gyromagnetic resonance linewidth ΔH and effective gyromagnetic ratio γ
eff
by non resonant method
12.1 General

So far the gyromagnetic resonance linewidth ΔH and the effective gyromagnetic ratio γ have

eff

been measured by using the resonant cavity as described in Clause 6. Therefore, the

measuring frequency is restricted to the frequency specified by a cavity resonator.

Meanwhile, various kinds of ferrite devices have been developed in a wide frequency range.

Accordingly it is desirable to measure the gyromagnetic resonance linewidth ΔH and the

effective gyromagnetic ratio γ easily at any frequency demanded for the development of

eff

ferrite materials or devices. Moreover, there are two problems in the cavity resonator method

described in Clause 6. One problem is the insufficient resolution of a magneto flux density

meter, which is apt to cause poor accuracy in the measurement of the narrow resonance

---------------------- Page: 6 ----------------------
SIST EN 60556:2007/A1:2017
IEC 60556:2006/AMD1:2016 – 3 –
© IEC 2016

linewidth. Another problem is that a ferrite sample becomes too small to be shaped into a

sphere or a disk, because it is necessary to reduce the size of a ferrite sample to keep the

resonance absorption increasing with the reduction of the resonance linewidth to proper

values in order to ensure a sufficiently small cavity perturbation. In Clause 12, the measuring

methods of the gyromagnetic resonance linewidth ΔH and the effective gyromagnetic ratio γ

eff
at an arbitrary frequency are described.
12.2 Object

To describe methods that can be used for measuring the gyromagnetic resonance linewidth

ΔH and the effective gyromagnetic ratio γ of isotropic microwave ferrites at an arbitrary

eff

frequency over the frequency range of 1 GHz to 10 GHz by the measurement of the changes

in transmission and reflection characteristics with frequency sweep.
12.3 Measuring methods
12.3.1 General

The measurements are performed by measuring the changes of transmission characteristics,

such as complex reflection coefficients or scalar transmission coefficients, in a transmission

line loaded with a ferrite sample with frequency sweep. The advent of a frequency synthesizer

and a receiver with low noise figure and a wide dynamic range in the microwave region has

made it possible to perform these measurements accurately.

Strictly speaking, the linewidth measured under frequency sweep and a constant external

magnetic field is not the same as the one measured under external magnetic field sweep and

a constant frequency as described in Clause 6. However the difference between two

measured values is small to the extent that it causes no problem in practical use.

As the measuring method, two methods can be considered as follows:

1) Reflection method – method measuring the reflection coefficients from the short-circuited

transmission line loaded with a ferrite sample.

2) Transmission method – method measuring the transmission power through a ferrite-

loaded coupling hole made in a common ground plane of the transmission lines crossing

at right angle.

These two methods have advantages and disadvantages in comparison with each other from

the standpoint of practical use. The reflection method has the advantage of a simple test

fixture’s structure, easier sample mounting and simpler measuring circuit arrangement due to

one port measurement, which is convenient for the measurement of temperature dependence

of the resonance linewidth. The transmission method has the advantage of being able to

measure the resonance linewidth by one ferrite sample in a wide frequency range and gives

more accurate measuring values of the resonance linewidth due to simpler measurement, i.e.

the measurement of the transmission power only, under careful making of a test fixture.

These two methods are enumerated in 12.3.2 and 12.3.3.
12.3.2 Reflection method
12.3.2.1 Measurement theory
The recommended method for measuring the gyromagnetic resonance linewidth ΔH and

effective gyromagnetic ratio γ is based on the measurement of the reflection coefficient S

eff 11

of a short-circuited transmission line with the specimen as proposed by Bady [20]. In this

standard, the short-circuited microstrip line is used as schematically shown in Figure 27.

---------------------- Page: 7 ----------------------
SIST EN 60556:2007/A1:2017
– 4 – IEC 60556:2006/AMD1:2016
© IEC 2016
Reference plane (virtual)
Stripline
Connector
for µ = 1
for FMR
H cal
ext
Short end
Ground
Specimen
IEC
Figure 27 – Schematic drawing of short-circuited
microstrip line fixture with specimen

The reference plane is defined by the length of the specimen from the short end. Seen from

the reference plane of the test fixture, the lumped element equivalent circuit can be assumed

to be a L C parallel circuit as in Figure 28a) when the strong magnetic field is applied

o o

parallel to the plane of specimen (x-direction) to achieve the situation of µ = 1. After removing

this field, the field is applied perpendicularly to the specimen plane for gyromagnetic

resonance. Figure 28b) shows the equivalent circuit for gyromagnetic resonance [21], where

L is an air core inductance and C is a parasitic capacitance. The values of L and C are

o o o o

designated “fixture constants”. The method to calculate “fixture constants” is shown in

12.3.2.8. When a gyromagnetic resonance occurs, it is considered that some portion η of air

core inductance L is replaced by the complex relative permeability µ’ µ”, and the coupling

coefficient η is almost invariable within the measurement frequency range. The half value

width of the resonant curve of the imaginary part µ” is defined as gyromagnetic resonance

linewidth. By measuring the S parameters of Figure 28a) and 28b), the quantity ηµ”L

11 o

proportional to the imaginary part µ” can be derived based on the circuit theory analysis as

shown in 12.3.2.5.

Consequently the gyromagnetic resonance linewidth ∆H is derived from the resonance curve

of ηµ”L .
ηµ’L ηωµ”L
o o
S ←
S ←
11o
(1 − η)L
C L C
o o o
a) b)
IEC IEC
Figure 28a) with µ = 1 under strong magnetic
Figure 28b) with gyromagnetic resonance
field parallel to r.f. magnetic field
Figure 28 – Equivalent circuits of short-circuited microstrip line
12.3.2.2 Test specimens and test fixtures

The structure of the all-shielded short-circuited microstrip line as test fixture is shown

schematically in Figure 29. A disk shape or square slab specimen is set at the end of the

short-circuited portion. To avoid disturbance from outside, the shielded covers are set up on

the upper side and both sides of the test fixture. The impedance of the test fixture except the

short end should be made at 50 Ω ± 2 Ω by adjusting the gap between the connector and the

strip line. The typical dimensions of the test fixture are shown in Table 1.
---------------------- Page: 8 ----------------------
SIST EN 60556:2007/A1:2017
IEC 60556:2006/AMD1:2016 – 5 –
© IEC 2016
Side shield cover a
Gap
(a) Top view
Side shield cover b
Microstrip line
Reference plane
Upper shield cover
Connector
2 (b) Side view
Specimen
Ground
(thickness t)
IEC
NOTE The thickness of the strip line is 0,3 mm.
Figure 29 – Cross-sectional drawing of all-shielded
shorted microstrip line with specimen
Table 1 – Typical dimensions of test fixture
h w h gap w L L
1 1 2 2 1 2
2,0 7,0 3,7 20 8 5
0,35 ± 0,15
NOTE Dimensions in mm.

The shapes of specimens are a disk or a square slab. The typical dimensions of specimens

are shown in Table 2.
Table 2 – Specimen shape and typical dimensions
Disk Diameter D Quotient of diameter and thickness
D ≤ 5 mm φ up to 10 GHz t/D ≤ 1/20 (t = thickness)
Square slab Side length Quotient of side length and thickness
L ≤ 5 mm up to 10 GHz t/ L ≤ 1/20 (t = thickness)
2 2
12.3.2.3 Measuring apparatus

Figure 30 shows the block diagram of this measurement method. The test fixture with a

specimen is located between pole pieces of permanent magnets or an electro magnet to

generate gyromagnetic resonance. In case of a disk or square slab, in order to apply a static

magnetic field in normal to plane, the test fixture and pole piece should be capable of rotating

along two different axes which are orthogonal to each other. Under the constant static

magnetic field, the absolute value and phase of the S parameter of the test fixture are

measured by the sweeping frequency of the vector network analyzer (VNA).
---------------------- Page: 9 ----------------------
SIST EN 60556:2007/A1:2017
– 6 – IEC 60556:2006/AMD1:2016
© IEC 2016
Rotation
VNA
Magnet a
ext
Cable
Rotation
Test fixture with specimen
Magnet b
IEC
Figure 30 – Block diagram of measurement system
12.3.2.4 Measuring procedure
The measuring procedure is as follows:

1) The VNA is calibrated on the cable end using an “open”, “short”, and “load” jig.

2) The total sweeping frequency points are selected so as to get more than 10 points within

the half linewidth ∆ f of the frequency defined below.

3) A specimen should be contacted and fixed on the corner of the short end and the ground.

4) To sustain the situation of µ = 1, a static magnetic field H larger than 3,2 × 10 A/m

cal
should be applied in parallel to the x-direction of the r. f. magnetic field.
5) The absolute value and phase of S are measured as shown in Equation (64).
11o
S = G exp(jδ ) (64)
11o o o

6) After removing H , the static magnetic field H is applied along the z-direction.

cal ext
7) The gyromagnetic resonance curve is observed in S .

8) The direction of H is adjusted to obtain the lowest resonant frequency, namely to be

ext

normal to the plane of the specimens, by rotating the test fixture and pole pieces

individually.

9) The minimum value S is measured at the resonant frequency. This value should be

11m
less than –1 dB.

10) Then the absolute value and phase of S are measured all over the frequency range as

shown in Equation (65).
S = G exp(jδ) (65)
12.3.2.5 Derivation of gyromagnetic resonance linewidth ∆H [21]
The derivation of gyromagnetic resonance linewidth is obtained as follows:

1) By dividing Equation (65) by Equation (64), E and F are defined as Equation (66).

S /S = G/ G exp{j(δ−δ )} = E + j F (66)
11 11o o o
2) Next, the calculations should be done.
C = y (E +1) + F X (67)
11 c
---------------------- Page: 10 ----------------------
SIST EN 60556:2007/A1:2017
IEC 60556:2006/AMD1:2016 – 7 –
© IEC 2016
C = X (E−1) − y F (68)
12 c
C = y { y (1−E) − F X } (69)
10 c
C = y { X (1+E) − F y} (70)
20 c
where
y is a characteristic admittance, usually y = 0,02 S.
X is defined by X = ω C −1/ωL (71)
c c o o
3) Also, the following calculations should be done.
C C − C C
10 11 20 12
A = (72)
2 2
C + C
11 12
C C + C C
10 12 20 11
B = (73)
2 2
C + C
11 12
4) The imaginary part ηµ”L of the complex inductance is calculated.
′′ (74)
ημ L =
o 2
ϖ{A + (B −ϖC ) }

5) The value of ηµ”L is directly proportional to µ”. With ηµ”L being on the vertical axis and

o o

the frequency being on the horizontal axis, the resonance curve can be drawn as shown in

Figure 31. In general, the curve is not always bilaterally symmetrical on the central

frequency axis. The resonant frequency f of the main peak and two half line widths of ∆f

r l

on the left and ∆f on the right could be derived. However, the smaller value of ∆f on the

h l

left side than of ∆f on the right side is adopted as a correct half width ∆ f because the

smaller one is considered to be less influenced by a higher magneto static mode. The

method to derive ∆f using the least square method is shown in 12.3.2.6.
6) The relaxation constant α is derived by the Equation (75) [22].
α = ∆f / f (75)

7) The gyromagnetic resonance linewidth ∆H is derived through Equation (76) [23].

∆H = 4π∆ f /(µ γ ) (A/m) (76)
o eff
where
µ is the permeability of vacuum;
γ is the effective gyromagnetic ratio.
eff
---------------------- Page: 11 ----------------------
SIST EN 60556:2007/A1:2017
– 8 – IEC 60556:2006/AMD1:2016
© IEC 2016
0,7
Max
α = 0,014 7
0,6
∆Η = 23,5 x 10 [T]
0,5
0,4
Max/2
MSW
0,3
(n = 3)
0,2
0,1
2,1 2,2 2,3 2,4 2,5
Frequency (GHz)
IEC
Figure 31 –Observed absorption curve of imaginary part ηµ”L of inductance
for a 5 mm square garnet specimen with 0,232 mm thickness and Ms = 0,08 T

NOTE If the amplitude and phase of S are measured with an accuracy of ±0,02 dB and ±0,075° respectively, the

static magnetic field strength is measured with an accuracy of ±1 %, and L and C are determined with an

o o

accuracy ±10 %, the relative error of γ becomes equal to ±1 % and the relative error in the determination of ∆H

eff
becomes equal to ±5 %, respectively.
12.3.2.6 The derivation of half line width ∆f by the least square method

First, as an example, the measurement values ηµ”L of about 10 pieces on the lower

frequency side and of about 4 pieces on the higher frequency side including the maximum

value of (ηµ”L ) are gathered. Next, the inverse value of (ηµ”L ) is denoted as a(0) and

o max o max

the inverse values of ηµ”L (i) on both sides are denoted as a(−10), a(−9), … a(−1), a(1), a(2),

and a(3). The corresponding frequencies are f(0), f(−10), f(−9), … f(−1), f(1), f(2), and f(3)

respectively, where the lowest frequency is f(−10). Then the new frequency sets of

F(i) = f(i)−f(−10) are introduced. The value of a(i) obeys the parabolic relation as in Equation

(77) because ηµ”L (i) has Lorentzian characteristics.
y(i) = P F(i) + Q F (i) + R (77)

where P, Q, and R are the coefficients which should be determined by the least square method.

The error function of E is defined as follows:
2 2 2 2

E = Σ{y(i)−a(i)} = Σ{ P F(i) + Q F(i) + R −a(i)} (i = −10, −9,… 0, 1, 2, 3) (78)

The partial differentiations are performed regarding P, Q, and R to minimize E .

Eventually, the coefficients of P, Q, and R could be determined by the next equations.

P = D /D, Q = D /D, R = D /D (79)
P Q R
where
X X X X A X X X X A X X X X A
4 3 2 2 3 2 4 2 2 4 3 2
D = X X X Dp = X A X X D = X X A X D = X X X A (80)
3 2 1 1 2 1 3 1 1 R 3 2 1
X X n A X n X A n X X A
2 1 1 2 2 1
Imaginary part of inductance ηµ”L (nH)
---------------------- Page: 12 ----------------------
SIST EN 60556:2007/A1:2017
IEC 60556:2006/AMD1:2016 – 9 –
© IEC 2016
where
4 3 2 0
X = Σ F(i) , X = Σ F(i) , X Σ F(i) , X = Σ F(i) , n = Σ F(i) (81)
4 3 2 = 1
X A = Σ F(i) a(i), X A = Σ F(i) a(i), A = Σ a(i) (82)
2 1
where n is the total number of the data. In this example n = 14.
As a result, the resonance frequency f is given by the Equation (83).
f = − Q /(2 P)+ f(−10) (83)
The half line width Δf is also given by the Equation (84).
4PR − Q
(84)
∆f =
12.3.2.7 Calculation of effective gyromagnetic ratio γ
eff
The value of γ could be derived through the next procedure.
eff

1) By changing an applied magnetic field from H to H , the resonant frequency f and f

1 2 r1 r2
can be measured correspondingly.
2) The effective gyromagnetic ratio γ is derived by Equation (85).
eff
2π( f − f )
r1 r2 −1 −1
γ = (T s ) (85)
eff
μ (H1 − H 2)
where
the frequency difference (f − f ) should be larger than 600 MHz.
r1 r2
12.3.2.8 Calculations of fixture constant L and C
o o

The equivalent circuit seeing a specimen with µ = 1 from the reference plane is assumed to

be a parallel circuit with L and C as shown in Figure 32.
o o
S ←
11o
Reference plane Shorted end
Specimen
IEC
Figure 32 – Assumed equivalent circuit of the test fixture

If the test fixture impedance is designed to be 50 Ω except the short end and the effect of the

loading sample with µ = 1 is negligible, the fixture constants of L and C are calculated as

o o
follows:
L = L L (H) (86)
o 2
---------------------- Page: 13 ----------------------
SIST EN 60556:2007/A1:2017
– 10 – IEC 60556:2006/AMD1:2016
© IEC 2016
C = 0,38 C L (F) (87)
o 2
where

L is the length of the sample, and L = 166,9 nH/m and C = 66,67 pF/m [24] are the

inductance and the capacitance per unit length of the 50 Ω transmission line. The factor of

0,38 in Equation (87) was determined to minimize the lumped element model error in the

wide measurement frequency range up to 10 GHz.
Table 3 shows the calculated fixture constants for 5 mm long specimens.
Table 3 – The fixture constants for 5 mm long specimens
Length of specimen L C
o o
mm nH pF
5 0,834 0,127
12.3.3 Transmission method
12.3.3.1 Theory

A method recommended for the evaluation of ΔH and γ at an arbitrary frequency is based

eff

on the measurement of the off-diagonal element of relative tensor permeability, κ, through a

signal transmission [25]. A test fixture model used in this measurement is shown in Figure 33.

The test fixture is constructed by two tri-plate lines stacked at right angle and a common

ground plane between them with a coupling hole at the cross point of the two lines. One line

used to apply an r.f. magnetic field to a specimen is terminated by a matched load to generate

a uniform r. f. magnetic field. The other line used to detect a signal from the specimen is

grounded at the edge of the coupling hole to avoid an error caused by leakage of an electric

field from the coupling hole. A grid parallel to the driving r. f. magnetic field is provided in the

coupling hole for further suppression of the electric field leakage.
Ferrite Coupling hole
Upper ground plane
Common ground plane
Detecting line
Driving line
Lower ground plane
Electric field leakage suppressing grid
IEC

(A part of the ground plane is cut away to show the bottom part of the test fixture.)

Figure 33 – Structure of test fixture to measure resonance linewidth by transmission

A ferrite specimen is positioned on the electric field leakage suppressor grid, facing the

detecting line. A magneto-static field orthogonal to the driving r. f. magnetic field is applied to

generate a precession of the electron spin in the ferrite and a gyromagnetic resonance. The

spin precession induces a signal in the detecting line. These relationships are shown in

Figure 34.
---------------------- Page: 14 ----------------------
SIST EN 60556:2007/A1:2017
IEC 60556:2006/AMD1:2016 – 11 –
© IEC 2016
Magneto-static field
z-axis
Spin precession
Induced magnetic flux (m )
r.f. magnetic field (h )
Induced signal (b)
y-axis
x-axis
Driving line
Ferrite
Electron spin
Detecting line
Driving power (a)
IEC

(A part of the ground plane is cut away to show the bottom part of test the fixture.)

Figure 34 – Model to measure resonance linewidth by transmission

Through the precession of the electron spin, the application of the magneto-static field to the

test fixture results in a coupling between the driving and the detecting lines as shown in

Equation (88) [25].
C = C + 20log(κ ) (88)
where

C is the coupling coefficient in dB defined by the diameter wavelength ratio of the hole;

κ is the off-diagonal element of relative tensor permeability of the ferrite specimen in the

coupling hole.

Equation (88) shows that the signal intensity obtained from the test fixture is proportional to

the absolute value of the off-diagonal element in the relative tensor permeability, κ , of the

magnetized ferrite. The resonance is defined by the magneto-static field strength and the

frequency to maximize the transmitted power, and the relationship between the resonance

frequency and the internal magnetic field of the specimen is written as shown in Equation (89).

γ H
eff i
(89)
f =
where
f is the resonance frequency;
γ is the effective gyromagnetic ratio;
eff
H is the internal magnetic field of the specimen.

The linewidth in the frequency, ∆f, is defined as the difference between the two frequencies f

and f at which the transmitted power by the ferrite material is one-half the maximum

transmission as shown below.
(90)
∆f = f − f
1 2

The line broadening by the external load is included in the linewidth. The broadening is

adjusted from the maximum value of the transmission as described in 12.3.3.5. The linewidth

---------------------- Page: 15 ----------------------
SIST EN 60556:2007/A1:2017
– 12 – IEC 60556:2006/AMD1:2016
© IEC 2016

described in the frequency is converted to the conventional linewidth in the magnetic field

strength by using the gyromagnetic ratio, γ . γ is a constant to define the resonance

eff eff

frequency from the internal magnetic field as shown in Equations (26) and (27) in Clause 6.

Considering that γ is independent from the shape of the specimen, it is calculated by two

eff
resonance conditions as shown in Equation (91).
2π( f − f )
r1 r2
(91)
γ =
eff
H − H
r1 r2
where
and f are the first and the second resonance frequencies, respectively;
r1 r2

H and H are the magnetic field strengths corresponding to the resonance, respectively.

r1 r2

The obtained linewidth in the frequency, ∆f, is converted to the conventional linewidth in the

magnetic field strength, ∆H, using γ . The details of the conversion are shown in 12.3.3.5 as

eff
well.
12.3.3.2 Test specimens and test fixtures

The test specimens for this method may be either spherical or disc-shaped. The specimen

dimension shall be small compared with the wavelength in the specimen. The spherical

specimen resonates at a lower magnetic field than the disc-shaped specimen. However, the

linewidth broadening due to the insufficient saturation magnetization of the specimen and spin

wave loss as referred to in Clause 6 will be observed in the spherical specimen. For disc

specimens, the quotient of the diameter and the thickness shall exceed 15. Although the

magnetic field should be increased, the ambiguities of the linewidth appearing in the spherical

specimen become less so in the disc-shaped specimen shaped as described above. For

specimens with a relatively narrow linewidth, the measurement result depends strongly on the

surface state of the specimen. It is recommended to finish the surface of the specimen by

referring to 6.4.

By way of an example, Figure 35 illustrates the whole structure of a test fixture to evaluate the

resonance linewidth for 1 GHz to 10 GHz by transmission.
Detecting port Specimen
Holder
Specimen mount
Detecting conductor
Driving conductor
Driving port
Clamping screw
Termination
Driving chamber
Detecting chamber
Common ground plane
A-A
IEC
Figure 35 – Test fixture for measurement of resonance linewidth by transmission

The test fixture is constructed with a driving chamber, a detecting chamber, a ground plane

with a coupling hole and a mount to maintain the transmission between them at a minimum

when the magnetic field is not applied. The transmission with no magnetic field is called the

isolation of the test fixture. A specimen is glued on a sample mount put in the detecting line to

be positioned at the centre of the coupling hole.
---------------------- Page: 16 ----------------------
SIST EN 60556:2007/A1:2017
IEC 60556:2006/AMD1:2016 – 13 –
© IEC 2016

The characteristic impedance of the test fixture should be the same as the impedance of the

network analyzer, 50 Ω. It is favourable to adjust to 50 Ω ± 2,5 Ω for the transmission line of

the test fixture. The characteristic impedance of a transition from a connector to a

transmission line should favourably be adjusted to 50 Ω ± 5 Ω. The error c
...

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