Saint Petersburg Electrotechnical University "LETI "

1886

TEP Conference presentation

Theme: «Resonance Method of Measuring a Stuff Dielectric

Properties at Microwave Frequencies»

Student: Dvortsov A. V.

Managers: Medvedeva N. Y.

Mikerov A. G.

The purpose of the work:

Investigation of the resonance method of measuring the dielectric properties of materials at microwave frequencies, which includes:

• methodology for calculating the dielectric constant, quality factor and loss tangent of the samples of materials

• calculation error of method• using this method to study

the degradation phenomena in packages of integrated circuits and dielectric materials.

Dvortsov A. V., 6202 2

1 1.5 2 2.5 3GHz

-200

-150

-100

-50

0

S21, dB - no sample - pattern Characteristics of the vector network

analyzer Rohde&Schwarz

ZVA-40: Operating frequency range:10 MHz-40 GHz The sensitivity of the frequency - 0,5 HzSensitivity of the transfer - 0,01 dB

Test bench

Measured parameters:- resonant frequency,- transfer coefficient(S21- parameter)

Vector Network Analyzer Rohde & Schwarz ZVA-40

Coaxial Resonator

Dvortsov A. V., 6202 3

Design scheme of the resonatorL

b a

Mobile terminal Movable sample holderSampleMicrowave input

Microwave input

L = 100 mma = 10 mmb = 20 mm

The equivalent circuit of the resonator:

Resonance condition: - impedance of the coaxial line

- wave number

- impedance of the capacitor С at a frequency ω

- input resistance of short-line

Dvortsov A. V., 6202 4

Calculation formulas

Capacity of the measured sample

Permittivity

Q-factor of the sample :

Loss tangent

Q-factor of empty resonator and resonator with the sample :

Capacity of a flat capacitor

Dvortsov A. V., 6202 5

Treatment of experimental results

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

1

2

3

4

5

f, GHz

ε

Sample under investigation

Measurement error was calculated :- for the resonant frequency- for the capacity- for permittivity

The dependence of the dielectric constant of the sample frequency

Physical 

quantity

1 mode 2 mode 3 mode 4 mode

f, GHz 0,618 1,947 3,302 4,707

ε 4,19 2,69 1,91 1,63

№

measurement

f (1 mode),

GHz

f (2 mode),

GHz

f (3 mode),

GHz

f (4 mode),

GHz

1 0,6184 1,944 3,298 4,709

2 0,6183 1,947 3,301 4,701

3 0,6186 1,944 3,302 4,707

4 0,6183 1,951 3,307 4,711

5 0,6185 1,948 3,3 4,705

The calculation results of ε

Dvortsov A. V., 6202 6

1

2

3

4

0 1 2 3 4 5 6

f, GHz

C,

pF

fresh _dry

fresh _ moistened

aged _dry

aged _ moistened

0 1 2 3 4 5 6

f,

baseline

baseline after exposure to moisture

agedaged after exposure 

to moisture

3

4

5

6

7

8

0 1 2 3 4 5

f, GHz

EMC_dry

EMC _ moistened

3

4

5

6

7

8

0 1 2 3 4 5

f,

baselinebaseline after exposure

 to moisture

aged

baseline

Results of the research

Epoxy Compound

Corps of Integrated Circuits

ε

Dvortsov A. V., 6202 7

Conclusion

• A method for measuring permittivity materials at microwave frequencies (UHF), based on the dependence of the resonance frequency of bulk coaxial microwave cavity of the electrical parameters embedded in the cavity of the samples of the materials.

• Calculated measurement error.

• The calculation of the dielectric constant epoxy compound and determined its dependence on frequency.

• Evaluated the possibility of applying the method to assess the degradation phenomena in packages of integrated circuits and dielectric materials.

Studies have shown that the investigated method is accurate, reliable and informative.

Dvortsov A. V., 6202 8

Dvortsov A. V., 6202 9