TEMASEK LABORATORIES Dielectric Resonance in Multi-phase Composites Leader: S. M. Matitsine Members: K. M. Hock, L. Liu, A. Qing, X. Xu, K. N. Rozanov,

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Dielectric Resonance in Multi-phase Composites

Leader: S. M. MatitsineMembers: K. M. Hock, L. Liu, A. Qing, X. Xu,

K. N. Rozanov, A. N. Lagarkov, Y. B. Gan

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10 mm/0.1 mm Cu Fibre in 0.5 mm Carbon Fibre

Typical sample To Increase Thickness

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Resonance condition = 2L

Resonance shift fres v/2L = (c/n)/2L = (c/2L)/n = f0/n

Refractive index n = Re(rr)

Absorption coeff. = Im(rr)

/n

L

v

r r

Background

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Near-field MeasurementNear-field Measurement

HP

Vector-analyser Metal Plate and sample

Frequency : 2 ~ 20 GHz

Calculation : ’ , ” , ’ , ”

HP

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Host - 15% Al powder (15 um)Sample thickness0.2 mm

Samplethickness1 mm

With Cu fibre (10 mm/0.1 mm)

an

d

an

d

an

d

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Bulk

Thin sample

Possible Reason for Resonance Shift in Thin Sample

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Measurement Results – Cu fibre resonance

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2b

2a

ed

abC

)/ln(2)/ln(2

1

(Lagarkov, et al 1998)

kaib

aL d2ln2

(Lagarkov and Sarychev 1996)

d = host permittivitye = effective permittivity

LCfres 2

1

Lagarkov’s and Sarychev’s Theory:

- Resonance shift depends on powder size, fibre length and thickness- Powders are assumed to be spherical and non-magnetic

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Scanning Electron Microscope (SEM) Images of Aluminium powder

15 um

15 um

5 um

4 um

Taken by Gao Xingsen, Dept Mat. Sci., NUS, May 2002

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E

E

Impedance Analyzer Measurement - 15% Al Sample

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HFSS* Simulation – Cu fibre in anisotropic host (15% Al)

*FEM simulation - ANSOFT

= 6 = 33

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HFSS* Simulation – Cu fibre in 15% Al host

*FEM simulation - ANSOFT

Thickness

= 6 = 33

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Compare with Measurement Results

Agree

Agree

Explain by Anisotropy

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