Title page for ETD etd-08082007-120136
|Type of Document
||Fidanboylu, Kemal M.
||Time domain synthesis applied to modeling of microwave structures and material characterization
|Riad, Sedki Mohamed
|Besieris, Ioannis M.
|Elshabini-Riad, Aicha A.
|Herdman, Terry L.
|Vanlandingham, Hugh F.
|Date of Defense
In this dissertation a new time domain approach for the determination of material
properties such as the complex permittivity and the complex permeability in a stripline geometry
is presented. The new technique uses both Time Domain Reflectometry (TDR) and Time
Domain Transmission (TDT) measurements for determining an optimum frequency dependent
lossy transmission line model for the stripline under test. The optimization is done in the time
domain by comparing the experimental TDR and TDT response waveforms with the simulated
ones using a non-linear least squares fit. The conventional optimization algorithms have shown
to be inefficient in this specific application. In this dissertation an efficient optimization
algorithm which has been developed to suit this application is also presented. In general, the
material properties in a stripline under test are related with the geometrical parameters of the line
through complicated integral expressions. Using the proposed approach, the use of complicated
integral expressions are avoided. The material properties such as the complex permittivity and
the complex permeability are determined from the optimum lossy transmission line model. For
this purpose, the frequency behavior of the line parameters have to be known beforehand in the
form of causal mathematical models. The literature survey shows that, no causal model exists for
the complex permittivity of thick film and polymer materials. The dissertation proposes a new
causal model for this purpose.
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