Shelley Begley Application Development Engineer Agilent Technologies

Shelley BegleyApplication Development EngineerAgilent Technologies

Electromagnetic Properties of Materials: Characterization at Microwave Frequencies and Beyond

Agenda

Definitions

Measurement TechniquesCoaxial Probe Transmission LineFree-Space Resonant Cavity

Summary

2

DefinitionsPermittivity 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

DkDf

'r

"r

Permittivity and Permeability Definitions

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

"'

0

rrrj

Permittivity (Dielectric Constant)



"'

0

rrrj


Dk



"'

0

rrrj

"'

0rr j

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


Permeability

Dk

"'rrr j "'

rrr j

Electromagnetic Field Interaction

Electric Magnetic

Permittivity Permeability

FieldsFields

STORAGE

MUT

STORAGE

"'rrr j "'

rrr j

Electromagnetic Field Interaction

Electric Magnetic

Permittivity Permeability

FieldsFields

STORAGE

LOSS

MUT

STORAGE

LOSS

Loss Tangent

'

"

tanr

r

CycleperStoredEnergy

CycleperLostEnergy

QD

1tan

Dissipation FactorD

Quality FactorQ

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.

cc f

2

11

11

10

100

10 100

Water at 20o C

f, GHz

most energy is lost at 1/t

'r

"r

j

s

1

)( :equation Debye

Techniques

Transmission LIne

ResonantCavity

Free Space

CoaxialProbe

Which Technique is Best?

It Depends…

Frequency of interest

Expected value of er and mr

Required measurement accuracy


It Depends… on



Required measurement accuracy Material properties (i.e., homogeneous, isotropic) Form of material (i.e., liquid, powder, solid, sheet) Sample size restrictions


It Depends… on



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

Measurement Techniques vs. Frequency and Material Loss

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


Frequency

Loss

Coaxial Probe


High

Medium

Low



Frequency

Loss

Transmission line

Coaxial Probe


High

Medium

Low

Free Space



Frequency

Loss

Transmission line

Resonant Cavity

Coaxial Probe


High

Medium

Low

Free Space


Coaxial Probe System

Network Analyzer (or E4991A Impedance

Analyzer)

85070EDielectric

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


• effectively infinite thickness

• non-magnetic

• isotropic

• homogeneous

• no air gaps or bubbles

Coaxial Probe

11

Reflection

(S )

er

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

Martini Meter!

80 85 90 95 100

Measured Y

80

85

90

95

100

Pre

d C

al

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



C)

GP-IB, LAN or USB

Transmission Line Sample Holders

Waveguide

Coaxial

Transmission Line

l

Reflection(S )11

Transmission(S )21


• sample fills fixture cross section

• no air gaps at fixture walls

• flat faces, perpendicular to long axis

• Known thickness > 20/360 λ


• sample fills fixture cross section

• no air gaps at fixture walls

• flat faces, perpendicular to long axis


er and mr

Transmission models in the 85071E Software

Algorithm Measured S-parameters Output

Nicolson-Ross S11, S21, S12, S22 εr and μr

NIST Precision S11, S21, S12, S22 εr

Fast Transmission S21, S12 εr

Poly Fit 1 S11, S21, S12, S22 εr and μr

Poly Fit 2 S12, S21 εr

Stack Two S21, S12 (2 samples) εr and μr

Reflection models in the 85071E Software

Algorithm Measured S-parameters Output

Short Backed S11 εr

Arbitrary Backed S11 εr

Single Double Thickness S11 (2 samples) εr and μr

Transmission Example Data

85071E Materials Measurement

Software

Transmission Free-Space System

Network Analyzer

Sample holder fixtured between two antennae



C)

GP-IB, LAN or USB

Non-Contacting method for High or Low Temperature Tests.

Free Space with Furnace

Transmission Free-Space


• Flat parallel faced samples

• Sample in non-reactive region

• Beam spot is contained in sample



• Flat parallel faced samples

• Sample in non-reactive region

• Beam spot is contained in sample


l

Reflection

(S11 )

Transmission

(S21 )

er and mr

Free Space Example Data

Resonant Cavity System

Resonant Cavity with sample

connected between ports.

Network Analyzer

GP-IB or LAN


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

00313.011

4

2.3032

1

css

cr

ss

sccr

QQV

V

fV

ffV

Resonant Cavity Technique

ffc

Qc

empty cavityfc = 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

00313.011

4

2.3032

1

css

cr

ss

sccr

QQV

V

fV

ffV

Resonant Cavity Technique

Q

fs ffc

sQc

empty cavity

sample insertedfc = 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 materialsYes

er” resolution ≤10-4

Noer” resolution ≥10-2

Thin Films and SheetsYes

10GHz sample thickness <1mm

No10GHz optimum thickness ~

5-10mm

Calibration Required No Yes

Measurement Frequency Coverage Single Frequency Broadband or Banded

Materials Ordering Convenience SpecialsModel

NumberDescription

85071E E19

E03

E04

E15

E07

Split Post Dielectric Resonators from QWED1.1GHz

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



For More Information

Visit our website at:

www.agilent.com/find/materials

For Product Overviews, Application Notes, Manuals, Quick Quotes,

international contact information…

http://www.agilent.com/find/materials

ReferencesR 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 SocietyNo. 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.

Shelley Begley Application Development Engineer Agilent Technologies

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