Date of Award

Fall 1994

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical and Computer Engineering

First Advisor

Haim Grebel

Second Advisor

Edip Niver

Third Advisor

Shih-Chang Wu

Abstract

Artificial Dielectrics have been characterized using transmission line and s- parameter measurements. The complex dielectric constant and loss of graphite filled and non-poled piezoelectric-aggregate (Polyvinylidene Fluoride, PVDF) filled plastic (PMMA) has been characterized at low (1kHz-10kHz range, i.e., the VLF, very low frequency, range) and microwave frequencies. The average diameter diameter of graphite particles used was thirty microns. Measurements were performed on very fine graphite (one micron diameter grains) and 30 micron sized grains for comparison purposes. Fine grain graphite particles exhibited a, larger real dielectric constant, probably owing to a larger dipole effect. The dielectric constant characterization has also been done for PVDF-graphite-PMMA aggregates. Dissipation factors have been calculated in all cases.

The very low frequency measurements have been done using lossy capacitance principles. The very low frequency behavior of graphite-PMMA. samples showed an anomaly at percolation point (about 15 % of graphite). PVDF-PMMA samples showed no anomaly within the range of concentration measured, probably owing to the fact that PVDF is a dielectric material. At microwave frequencies, it is found that both real and imaginary parts of the dielectric constant experience an increase with the increase in graphite/PVDF loading.

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