Electromagnetic Properties of Materials:

wizzstuffingUrban and Civil

Nov 16, 2013 (3 years and 6 months ago)

168 views

Shelley Begley

Application Development Engineer

Agilent Technologies

Electromagnetic Properties of Materials:
Characterization at Microwave Frequencies and Beyond

Agenda




Definitions


Measurement Techniques


Coaxial Probe



Transmission Line


Free
-
Space



Resonant Cavity



Summary





2

Definitions

Permittivity is a physical quantity that
describes how an electric field affects and is
affected by a dielectric medium and is
determined by the ability of a material to
polarize in response to an applied electric
field, and thereby to cancel, partially, the
field inside the material. Permittivity relates
therefore to a material's ability to transmit
(or "permit") an electric field…The
permittivity of a material is usually given
relative to that of vacuum, as a relative
permittivity, (also called dielectric constant
in some cases)….
-

Wikipedia

Dk
Df
'
r

"
r

Permittivity and Permeability Definitions

interaction of a material in the
presence of an external electric field.

"
'
0
r
r
r
j










Permittivity

(Dielectric Constant)

Permittivity and Permeability Definitions

interaction of a material in the
presence of an external electric field.

"
'
0
r
r
r
j










Permittivity

(Dielectric Constant)

Dk
Permittivity and Permeability Definitions

interaction of a material in the
presence of an external electric field.

"
'
0
r
r
r
j










"
'
0
r
r
j








interaction of a material in the
presence of an external magnetic field.

Permittivity

(Dielectric Constant)

Permeability

Dk
Permittivity and Permeability Definitions

interaction of a material in the
presence of an external electric field.

"
'
0
r
r
r
j










"
'
0
r
r
j








interaction of a material in the
presence of an external magnetic field.

Permittivity

(Dielectric Constant)

Permeability

Dk
"
'
r
r
r
j





"
'
r
r
r
j





Electromagnetic Field Interaction

Electric

Magnetic

Permittivity

Permeability

Fields

Fields

STORAGE

MUT

STORAGE

"
'
r
r
r
j





"
'
r
r
r
j





Electromagnetic Field Interaction

Electric

Magnetic

Permittivity

Permeability

Fields

Fields

STORAGE

LOSS

MUT

STORAGE

LOSS

Loss Tangent

'
"
tan
r
r




Cycle
per
Stored
Energy
Cycle
per
Lost
Energy
Q
D



1
tan

Dissipation Factor

D
Quality Factor

Q
r

'
r

'
'
r

Df
Relaxation Constant
t

t

= Time required for 1/e of
an aligned system to return
to equilibrium or random
state, in seconds
.

c
c
f


t
2
1
1


1

1

10

100

10

100

Water at 20
o

C

f,
GHz

most energy is lost at 1/
t

'
r

"
r

t





j
s






1
)
(

:
equation

Debye
Techniques

Transmission
LIne


Resonant

Cavity

Free Space

Coaxial

Probe

Which Technique is Best?

It Depends…



Frequency of interest



Expected value of
e
r
and
m
r



Required measurement accuracy

Which Technique is Best?

It Depends… on



Frequency of interest



Expected value of
e
r
and
m
r



Required measurement accuracy



Material properties (i.e., homogeneous, isotropic)



Form of material (i.e., liquid, powder, solid, sheet)



Sample size restrictions

Which Technique is Best?

It Depends… on



Frequency of interest



Expected value of
e
r
and
m
r



Required measurement accuracy



Material properties (i.e., homogeneous, isotropic)



Form of material (i.e., liquid, powder, solid, sheet)



Sample size restrictions



Destructive or non
-
destructive



Contacting or non
-
contacting



Temperature

Which Technique is Best?

It Depends… on

Measurement Techniques

vs. Frequency and Material Loss

Frequency

Loss

Transmission line

Resonant Cavity

Coaxial Probe

Microwave

RF

Millimeter
-
wave

Low frequency

High

Medium

Low

Free Space

50 MHz

20 GHz

40 GHz

60 GHz

5 GHz

500+ GHz

Measurement Techniques

vs. Frequency and Material Loss

Frequency

Loss

Coaxial Probe

Microwave

RF

Millimeter
-
wave

Low frequency

High

Medium

Low

50 MHz

20 GHz

40 GHz

60 GHz

5 GHz

500+ GHz

Measurement Techniques

vs. Frequency and Material Loss

Frequency

Loss

Coaxial Probe

Microwave

RF

Millimeter
-
wave

Low frequency

High

Medium

Low

50 MHz

20 GHz

40 GHz

60 GHz

5 GHz

500+ GHz

Measurement Techniques

vs. Frequency and Material Loss

Frequency

Loss

Transmission line

Coaxial Probe

Microwave

RF

Millimeter
-
wave

Low frequency

High

Medium

Low

Free Space

50 MHz

20 GHz

40 GHz

60 GHz

5 GHz

500+ GHz

Measurement Techniques

vs. Frequency and Material Loss

Frequency

Loss

Transmission line

Coaxial Probe

Microwave

RF

Millimeter
-
wave

Low frequency

High

Medium

Low

Free Space

50 MHz

20 GHz

40 GHz

60 GHz

5 GHz

500+ GHz

Measurement Techniques

vs. Frequency and Material Loss

Frequency

Loss

Transmission line

Resonant Cavity

Coaxial Probe

Microwave

RF

Millimeter
-
wave

Low frequency

High

Medium

Low

Free Space

50 MHz

20 GHz

40 GHz

60 GHz

5 GHz

500+ GHz

Coaxial Probe System

Network Analyzer


(or E4991A Impedance
Analyzer)

85070E

Dielectric
Probe

GP
-
IB, LAN or
USB

85070E Software
(included in kit)

Calibration is required

Computer

(Optional for PNA or ENA
-
C)

Material assumptions:



effectively infinite thickness



non
-
magnetic



isotropic



homogeneous


no air gaps or bubbles

Coaxial Probe

1
1

Reflection

(S )


r


Three Probe Designs

High Temperature Probe



0.200


20GHz (low end 0.01GHz with impedance
analyzer)


Withstands
-
40 to 200 degrees C


Survives corrosive chemicals


Flanged design allows measuring flat surfaced solids.

Three Probe Designs

Slim Form Probe



0.500


50GHz


Low cost consumable design


Fits in tight spaces, smaller sample sizes


For liquids and soft semi
-
solids only






Three Probe Designs

Performance Probe


Combines rugged high temperature performance
with high frequency performance, all in one slim
design.




0.500


50GHz


Withstands
-
40 to 200 degrees C


Hermetically sealed on both ends, OK for autoclave


Food grade stainless steel







Coaxial Probe Example Data

Coaxial Probe Example Data

Coaxial Probe Example Data

Martini Meter!

80
85
90
95
100
Measured Y
80
85
90
95
100
Pred Cal
100 real
96.6 real
80.0 real
98.0 real
90.9 real
99.5 real
96.2 real
97.6 real
87.0 real
99.0 real
95.7 real
97.1 real
83.3 real
98.5 real
95.2 real
5
Infometrix, Inc.

Transmission Line System

Network Analyzer

Sample holder

connected between coax cables

85071E Materials
Measurement
Software

Calibration is required

Computer

(Optional for PNA or ENA
-
C)

GP
-
IB, LAN or
USB

Transmission Line Sample Holders

Waveguide

Coaxial

Transmission Line

l

Reflection

(S )

11

Transmission

(S )

21

Material assumptions:



sample fills fixture cross section



no air gaps at fixture walls



flat faces, perpendicular to long axis



Known thickness > 20/360
λ


r
and


r

Transmission m
odels

in the 85071E Software



Algorithm

Measured S
-
parameters

Output


Nicolson
-
Ross

S11, S21, S12, S22

ε
r

and

μ
r


NIST Precision

S11, S21, S12, S22

ε
r

Fast Transmission

S21, S12

ε
r

Poly Fit 1

S11, S21, S12, S22

ε
r

and

μ
r

Poly Fit 2

S12, S21

ε
r

Stack Two

S21, S12 (2 samples)

ε
r

and

μ
r

Reflection m
odels

in the 85071E Software



Algorithm

Measured S
-
parameters

Output


Short Backed

S11

ε
r

Arbitrary Backed

S11

ε
r

Single Double Thickness

S11 (2 samples)

ε
r

and

μ
r


Transmission Example Data

Transmission Example Data

85071E Materials
Measurement
Software

Transmission Free
-
Space System

Network Analyzer

Sample holder

fixtured between two antennae

Calibration is required

Computer

(Optional for PNA or ENA
-
C)

GP
-
IB, LAN or
USB

Non
-
Contacting method for High or Low
Temperature Tests.

Free Space with Furnace

Transmission Free
-
Space

Material assumptions:



Flat parallel faced samples



Sample in non
-
reactive region



Beam spot is contained in sample



Known thickness > 20/360
λ

l

Reflection

(S11 )

Transmission

(S21 )


r
and


r

Free Space Example Data

Free Space Example Data

Resonant Cavity System

Resonant Cavity with sample

connected between ports.

Network Analyzer

GP
-
IB or LAN

Computer

(Optional for PNA or ENA
-
C)

Resonant Cavity
Software

No calibration required

Resonant Cavity Fixtures

Agilent Split Cylinder
Resonator IPC TM
-
650
-
2.5.5.5.13

Split Post Dielectric
Resonators from QWED

ASTM 2520 Waveguide
Resonators



00313
.
0
1
1
4
2.303
2
1


















c
s
s
c
r
s
s
s
c
c
r
Q
Q
V
V
f
V
f
f
V


Resonant Cavity Technique

f

f

c

Q

c

empty cavity

fc = Resonant Frequency of Empty Cavity

fs = Resonant Frequency of Filled Cavity

Qc = Q of Empty Cavity

Qs = Q of Filled Cavity

Vs = Volume of Empty Cavity

Vc = Volume of Sample

ASTM 2520

S21



00313
.
0
1
1
4
2.303
2
1


















c
s
s
c
r
s
s
s
c
c
r
Q
Q
V
V
f
V
f
f
V


Resonant Cavity Technique

Q

f

s

f

f

c

s

Q

c

empty cavity

sample inserted

fc = Resonant Frequency of Empty Cavity

fs = Resonant Frequency of Filled Cavity

Qc = Q of Empty Cavity

Qs = Q of Filled Cavity

Vs = Volume of Empty Cavity

Vc = Volume of Sample

ASTM 2520

S21



00313
.
0
1
1
4
2.303
2
1


















c
s
s
c
r
s
s
s
c
c
r
Q
Q
V
V
f
V
f
f
V


Resonant Cavity Technique

Q

f

s

f

f

c

s

Q

c

empty cavity

sample inserted

fc = Resonant Frequency of Empty Cavity

fs = Resonant Frequency of Filled Cavity

Qc = Q of Empty Cavity

Qs = Q of Filled Cavity

Vs = Volume of Empty Cavity

Vc = Volume of Sample

ASTM 2520

S21



00313
.
0
1
1
4
2.303
2
1


















c
s
s
c
r
s
s
s
c
c
r
Q
Q
V
V
f
V
f
f
V


Resonant Cavity Technique

Q

f

s

f

f

c

s

Q

c

empty cavity

sample inserted

fc = Resonant Frequency of Empty Cavity

fs = Resonant Frequency of Filled Cavity

Qc = Q of Empty Cavity

Qs = Q of Filled Cavity

Vs = Volume of Empty Cavity

Vc = Volume of Sample

ASTM 2520

S21

Resonant Cavity Example Data

Resonant vs. Broadband Transmission Methods

Resonant

Broadband

Low Loss materials

Yes

e
r
” resolution ≤10
-
4

No

e
r
” resolution ≥10
-
2

Thin Films and Sheets

Yes

10GHz sample thickness
<1mm

No

10GHz optimum thickness ~
5
-
10mm

Calibration Required

No

Yes

Measurement Frequency
Coverage

Single Frequency

Broadband or Banded

Materials Ordering

Convenience Specials



Model Number

Description

85071E


E19

E03

E04

E15

E07

Split Post Dielectric Resonators from QWED

1.1GHz

2.5GHz

5GHz

15GHz

22GHz


85071E


E02

E01

E22

E18

E24


Quasi
-
optical products from Thomas Keating Ltd.

60
-
90GHz


Quasi
-
optical Table

75
-
110GHz


Quasi
-
optical Table

90
-
140GHz


Additional set of horns for above tables

220
-
326GHz


Additional set of horns for above tables

325
-
500GHz


Additional set of horns for above tables


Materials Ordering

Convenience Specials



Model Number

Description

85071E


E19

E03

E04

E15

E07

Split Post Dielectric Resonators from QWED

1.1GHz

2.5GHz

5GHz

15GHz

22GHz


85071E


E02

E01

E22

E18

E24


Quasi
-
optical products from Thomas Keating Ltd.

60
-
90GHz


Quasi
-
optical Table

75
-
110GHz


Quasi
-
optical Table

90
-
140GHz


Additional set of horns for above tables

220
-
326GHz


Additional set of horns for above tables

325
-
500GHz


Additional set of horns for above tables


For More Information

Visit our website at:

www.agilent.com/find/materials




For Product Overviews, Application Notes,
Manuals, Quick Quotes, international contact
information…

References


R N Clarke (Ed.), “
A Guide to the Characterisation of
Dielectric Materials
at RF and Microwave Frequencies,”

Published by
The Institute of Measurement & Control (UK) & NPL, 2003


J. Baker
-
Jarvis, M.D. Janezic, R.F. Riddle, R.T.
Johnk
, P.
Kabos
, C. Holloway, R.G. Geyer, C.A. Grosvenor,
“Measuring the
Permittivity and Permeability of
Lossy

Materials: Solids, Liquids, Metals, Building Materials, and Negative
-
Index Materials,”

NIST Technical Note 15362005



Test methods for complex permittivity (Dielectric Constant) of solid electrical insulating materials at microwave frequencies

and temperatures to 1650
°
,


ASTM Standard D2520, American Society for Testing and Materials


Janezic M. and Baker
-
Jarvis J.,
“Full
-
wave Analysis of a Split
-
Cylinder Resonator for Nondestructive Permittivity
Measurements,”

IEEE Transactions on Microwave Theory and Techniques vol. 47, no. 10, Oct 1999, pg. 2014
-
2020


J.
Krupka

, A.P. Gregory, O.C.
Rochard
, R.N. Clarke, B. Riddle, J. Baker
-
Jarvis,

“Uncertainty of Complex Permittivity
Measurement by Split
-
Post Dielectric Resonator Techniques,”
Journal of the European Ceramic Society

No. 10, 2001, pg. 2673
-
2676


“Basics of
Measureing

the Dielectric Properties of Materials”.

Agilent application note.
5989
-
2589EN


AM. Nicolson and G. F. Ross, "Measurement of the intrinsic properties of materials by time domain techniques,"
IEEE Trans.
Instrum
. Meas
., IM
-
19(4), pp. 377
-
382, 1970.




Improved Technique for Determining Complex Permittivity with the Transmission/Reflection Method, James Baker
-
Jarvis et
al, IEEE transactions on microwave Theory and Techniques
vol

38, No. 8 August 1990



P. G. Bartley, and S. B. Begley, “A New Technique for the Determination of the Complex Permittivity and Permeability of
Materials
Proc. IEEE Instrument Meas. Technol. Conf
., pp. 54
-
57, 2010.