Characterizinggg Electromagnetic Properties of Materials

Characterizing Electromagnetic g gProperties of Materials

at 110GHz and Beyondat 110GHz and Beyond

Jeffrey Hesler Virginia Diodes Inc.Shelley Begley Agilent TechnologiesSuren Singh Agilent TechnologiesPhil Bartley IMSPhil Bartley IMS

Making Reliable Measurementsat mm and Sub-mm Wavelengths

Agenda

C ?•Why Characterize Material Properties?•Measurement System•Calibration•Measurement Results


Electromagnetic Materials

Radar Absorbing and Stealth MaterialsRadome MaterialsRadome MaterialsElectronic Substrate and Packaging MaterialsSpecific Absorption Rate (SAR) PhantomsMeta-materialsMeta materials


Why Materials Characterization?

Characterizing Electromagnetic Properties of Materials at 110GHz and beyond

Important for:Circuit designMilitary ApplicationsCar Radar ApplicationsNew Materials ResearchIncoming InspectionIncoming Inspection Quality AssuranceHealth and Safetyand moreand more…


Permittivity and Permeability

Permittivity Permeability

Definitions

"' jμ"' jε

Permittivity (Dielectric Constant)

Permeability

0rr jμμ

μμμ −==

0rrr jεεε

εκ −===

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

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

Making Reliable Measurementsat mm and Sub-mm Wavelengths\

Electromagnetic Field Interaction

Electric MagneticFieldsFields

STORAGE

Permittivity Permeability

Fieldse ds

MUT

LOSS

"'rrr jμμμ −="'

rrr jεεε −=STORAGE

Dielectric ConstantLOSS


Loss Tangent

ε''

rε

'"tan '

"

κκ

εεδ ==

r

rrε

'ε εr

CycleperLostEnergy1

rε

CycleperStoredEnergyCycleperLostEnergy

QD ===

1tanδ

Dissipation Factor Quality FactorD Q


Measurement Techniques

Loss

vs. Frequency and Material Loss

Coaxial ProbeHigh

Parallel Plate

Transmission line

Medium Free SpacePlate

FrequencyResonant CavityLow

50 MHz 20 GHz 40 GHz 60 GHz5 GHz 750+ GHz


MicrowaveRF mm/Submm-wave

Transmission Free-Space

Material assumptions:• Flat parallel faced samplesMaterial assumptions:• Flat parallel faced samples• Flat parallel faced samples• Sample in non-reactive region• Beam spot is contained in sample• Known thickness > 20/360

• Flat parallel faced samples• Sample in non-reactive region• Beam spot is contained in sample• Known thickness > 20/360Known thickness 20/360Known thickness 20/360

l

Reflection(S11 )

Transmission(S21 )


mm-Submm Wave System

Agilent PNA-X dual source network

analyzeranalyzer

Sample in holderVirginia Diodes Inc Sample in holder between two antennae

Agilent Materials Measurement Software

Virginia Diodes Inc. Transmit and Receive

(TR) Frequency Extenders


with Free Space Calibration

mm-Submm Wave System Photo


mm-Submm Wave System Photo


VDI Frequency Extenders & Horns

VDI offers frequency yextenders from 75GHz through 750GHz with outstanding dynamic range.


PNA-X mmWave Setup


Calibration is Required

Before a measurement can be made, a calibration must be performed to remove systematic errors.


TRM Calibration

Thru

Reflect

MatchMatch


TRL Calibration

Thru

ReflectMove the antenna away to compensate for the thickness of the short. Move it back for the next step

Line

step.

Move the antenna away on a quarter-wavelengthLine on a quarter-wavelength and then back in the original position.


Gated Reflect Line (GRL) Calibration

T t lib ti t id i t i t t

Two Tiered Calibration

Two port calibration at waveguide or coax input into antennas removes errors associated with network analyzer and cables.

ECal, SOLT or TRL Cal done here


Gated Reflect Line (GRL) Calibration

T dditi l f lib ti t d d

Two Tiered Calibration

•Two additional free space calibration standards remove errors from antennas and fixture.

Line (empty fixture)

Reflect (metal plate of known thickness)


GRL Cal Error Model

2-port Cal Terms 2-port Cal TermsMUT

forward only

p p

D Ms

Tt

Ml

1

S11 S22

S21

GRL Error Adapter

GRL Error Adapter

•Coax or Waveguide 2-port Cal corrects errors from end of cable back into

Tr S12

Adapter Adapter

g pthe instrument.


GRL Cal Error Model


forward only

p p

D Ms

Tt

Ml

1

S11 S22

S21

GRL Error Adapter

GRL Error Adapter


Tr S12

Adapter Adapter

g pthe instrument.

•Errors from Antennas and Fixture can be thought of as being lumped into a GRL error adapter.

•The GRL error adapter is quantified by measurements of reflect and line standards.


GRL Cal Error Model

MUT

S11 S22

S21

T22 T11

T12

O11 O22

O21

S12 T21O12

Six Unknowns

O21 = O12 T21 = T12Need ThreeO11

O22

T11

T22

Need Three Standards!


Gated “Standard”

0.00

S11 Time Domain - Empty Fixture3201 points used to avoid aliasing

Mi P i t 1 Ali F R ( ) * F S (H )

-30.00

-20.00

-10.00

time domain gate includes only reflections

before sample

Min Points = 1 + Alias Free Range (s) * Frequency Span (Hz)

-60.00

-50.00

-40.00

Mag

(S) (

dB)

-90.00

-80.00

-70.00

Transmitting Antenna

Receiving Antenna

-100.00-2.00 0.00 2.00 4.00 6.00 8.00 10.00

Time (ns)

S11 (dB) Linear (S11 (dB))

Antenna Antenna

sample holder


S11 (dB) Linear (S11 (dB))

GRL Cal Error Model

MUT

S11 S22

S21

T22

T12

O22

O21

S12 T21O12

Four Unknowns

O21 = O12 T21 = T12

O22 T22


Metal Plate Standard

P11 = P22 = -1 MUT

S21 T12O21

P21=P12=0. S11 S22

S12

T22

T21

O22

O12

21 12plate_1

22

O O1 O

Γ = −+

21 12plate_2

T T1 T

Γ = −+ 221 T+


Line Standard

A11=A22=0 MUT

S21 T12O21

A21 = A12 =

ω= frequency

j ude ω ε−S11 S22

S12

T22

T21

O22

O12ε= permittivity of airμ= permeability of air.d= thickness of the metal plate

21 12 21 12 22air_1

22 22

A A O O T1 O T

Γ =−

21 12 21 12 22air_2

22 22

A A T T O1 T O

Γ =−


22 22

GRL Cal Error Model


forward only

p p

D Ms

Tt

Ml

1

S11 S22

S21

GRL Error Adapter

GRL Error Adapter

Calibration planes are at the surface of


Tr S12

Adapter Adapterthe metal plate.

g pthe instrument.

•Errors from Antennas and Fixture can be thought of as being lumped into a GRL error adapter.

•The GRL error adapter is quantified by measurements of reflect and line standards.

•The original 2-port Cal is modified to correct for the error adapter.


Transmission Models

Algorithm Measured S-parameters Output

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

NIST Precision S11,S21,S12,S22 εr

F t S21 S12Fast S21,S12 εr

Poly Fit S11 S21 S12 S22 ε and μPoly Fit S11,S21,S12,S22 εr and μr

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


, ( p ) εr a d μr

Measurement Results


Measurement Results


Measurement Results

Multiple solutions can occur when sample is thicker

than 1 wavelength

The correct solution is obtained byis obtained by

giving a permittivity estimate


sample is 2.36mm thick

Measurement Results


Future Work

T i ith Th K ti h d f Q i• Try again with Thomas Keating horns made for Quasi-optical table.

• Method for determining number phase rotations in sample.

• Model for low loss samples.


Thank You


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 B k J i M D J i R F Riddl R T J h k P K b C H ll R G G C A GJ. 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 Materialsfrequencies and temperatures to 1650 , ASTM Standard D2520, American Society for Testing and Materials

“Basics of Measuring the Dielectric Properties of Materials”. Agilent application note. 5989-2589EN, April 28, 2005

Deepak K. Ghodgaonkar et al; “Free Space Method for Measurement of Dielectric Constants and Loss Tangents at Microwave Frequencies”; IEEE Transactions on IM volume 37 number 3 June 1989Microwave Frequencies ; IEEE Transactions on IM volume 37 number 3, June 1989.

P. Bartley, S. Begley, “Improved Free-Space S-Parameter Calibration” IMTC 2005 – Instrumentation and Measurement Technology Conference Ottawa, Canada, 17-19 May 2005


Documents

Characterizinggg Electromagnetic Properties of Materials