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W35: Measuring the Dielectric Properties of Materials
PageAgenda 2
• Definitions• VNA Measurement Techniques• Demo• Summary
Page
Material
Measurements
Permittivity and Permeability Definitions
interaction of a material in the presence
of an external electric field.
"'
0
rrr jµ
"'
0
rrrj
interaction of a material in the presence of an external magnetic field.
Permittivity (Dielectric Constant)
Permeability
3
Electric Magnetic
FieldsFields
MUT
STORAGE
LOSS𝜇𝑟′′𝜀𝑟
′′
𝜇𝑟′𝜀𝑟
′
Page
Transmission Line
Resonant
Cavity
Free Space
Coaxial
Probe
Parallel Plate
(Capacitance)
Inductance
16451B/53A
16454A
ASTM 2520
SPDR
Impedance
analyzer
solutions
Microwave Measurement Methods
4
Page
Material
Measurements
Which Technique is Best?
✓ Frequency of interest
✓ Expected value of εr
✓ 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
It Depends… on
5
Page
Material
Measurements
Measurement Techniques vs. Frequency and Material Loss
Parallel Plate
Frequency
Loss
Transmission line
Resonant Cavity
Coaxial Probe
MicrowaveRF Millimeter-waveLow frequency
High
Medium
Low
Free Space
50 MHz 20 GHz 40 GHz 60 GHz5 GHz 500+ GHz
6
Page
Material
Measurements
5952-1430E:
LCR Meters, Impedance Analyzers,
and Test Fixtures Selection Guide
5950-3000:
Impedance Measurement
Handbook
5980-2862EN:Solutions for Measuring Permittivity
and Permeability with LCR Meters and
Impedance Analyzers
5989-2589EN:
Basics of Measuring the
Dielectric Properties of Materials
New Application Briefs
Available
5991-4713EN
5991-4714EN
5991-4715EN
5991-4716EN
5991-4717EN
5991-4739EN
Keysight Literature:
7
Page
Material
Measurements
Demo
8
Self-Guided
Demo
Page
Material
Measurements 9
Page
Material
Measurements 10
Page
Material
Measurements 11
Page
Material
Measurements 12
Page
Material
Measurements 13
Page
Material
Measurements 14
Page
Material
Measurements 15
Set to
200 MHz
Page
Material
Measurements 16
Page
Material
Measurements 17
Page
Material
Measurements
Questions?
18
Q&A
Page 19
Page
Material
Measurements
For more information…
–Visit our website at:
www.keysight.com/find/materials
For Product Overviews, Application Notes, Manuals, Quick Quotes…
Plus, a free 30 day trial of N1500A software!
20
Page
Backup Material
21
Page
Material
Measurements
Summary Technique and Strengths
Parallel Plate Low Frequency
Best for thin flat sheets
Coaxial Probe Broadband
Best for liquids, semi-solids
Transmission Line Broadband
Best for machine-able solids
Transmission Free Space Broadband, mm-wave
Non-contacting
Resonant Cavity Single frequency
High accuracy, Best for low loss, or very thin samples
22
Page
Material Measurement MethodsFor microwave to mm-Wave (100 MHz to 1.1 THz)
23
Methods Reflection methods Transmission/Reflection
methods
Resonant methods
(Single point)
Measurement
theory
𝑌 = 𝐺 + 𝑗𝐵𝑦 = Τ𝑌 𝑌0 = 𝑌𝑍0
𝜀𝑟′ =
𝜆
2𝜋𝑑𝐼𝑚 𝑦 , 𝜀𝑟
" =𝜆
2𝜋𝑑𝑅𝑒 𝑦
(for d<<λ), cf.𝜆
2𝜋=
𝑐
𝜔
Γ = 𝑋 ± 𝑋2 − 1, 𝑋 =𝑆112 −𝑆21
2 +1
2𝑆11
𝑇 =𝑆11 + 𝑆21 − Γ
1 − (𝑆11 + 𝑆21)Γ𝜇𝑟
𝜀𝑟=
1+Γ
1−Γ
2, 𝜇𝑟𝜀𝑟 = −
𝑐
𝜔𝑑ln
1
𝑇
2
NRW algorithm(Γ: Reflection, T: Transmission coefficient)
𝜀𝑟′ = 1 +
𝑉𝑐 𝑓𝑐 − 𝑓𝑠2𝑉𝑠𝑓𝑠
𝜀𝑟" =
𝑉𝑐4𝑉𝑠
1
𝑄𝑠−
1
𝑄𝑐ASTM 2520
Measurement
techniques
Coaxial probe (εr) Resonant cavity (εr or μr)
Transmission line, Free space (εr, μr)
Planar circuit (εr, μr)
d
fs fc
empty cavitysample inserted
QsQc
d λ/4
Z0 Z(εr)
Open
Material
Measurements
Page
Material
Measurements
.0001 .001 .01 .1 1.00001
1
2
5
10
20
50
100
Wood
0%
10%
20%
Ice
Alcohol
Steak
Water Salt
Mylar
AirTeflon
Quartz
Alumina
TiO Water2
PC Board
Low Loss Lossy
'r
'" /tan rr
Dielectric Properties of Some Common Materials
Page
Material
Measurements
Dielectric Properties of Water
Page
Material
Measurements 26
Page
Material
Measurements 27
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