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In this dissertation, the full-wave characteristics of
various coplanar waveguide
discontinuities are studied and applied to microwave and
millimeter-wave filter
designs.
First, the full-wave algorithm of mixed potential integral
equation with moment
method is applied to solve the equivalent magnetic current
distributions on the
apertures of coplanar waveguide discontinuity structures. From the current
distributions, the far field patterns and power losses of
both radiation and surface
waves are obtained by deriving novel formulas which are concise, simple, and
efficient for computation. In the meantime, the matrix pencil
approach is applied to
extract the scattering parameters and from which, obtain the
total power loss by
circuit theory. Good agreement between the calculated
radiation and surface wave
losses by field theory and the total power loss by circuit theory verifies the
correctness of our new expressions.
The full-wave analysis is extended to deal with the coplanar waveguide
discontinuities with finite metallization thickness by
hybridizing the mixed potential
integral equation with the finite element method for the
electric field in the slot
region between upper and lower half spaces. The edge profile
effects of trapezoidal
slot cross section resulted from the etching or sputtering
process are also considered.
As the metallization thickness is comparable to the slot and
strip widths, it has been
shown from the numerical results that not only the
metallization thickness but also
the conductor edge profile can produce noticeable effects on
circuit performance and
should be taken into account for accurately modeling the coplanar waveguide
discontinuities.
After successfully establishing the full-wave
characterization techniques for
various CPW discontinuities, five different types of filters
are designed and analyzed.
The RBW type and impedance transformer type filters are suitable for wide-band
applications, while capacitive-coupled half-wave filter,
inductive-coupled half-wave
filter, and LC-coupled quarter-wave filter are suitable for
narrow-band applications.
For each type of filter, design theory and procedure are presented and clearly
explained. In the design phase, quasi-static equivalent
circuits are employed for
circuit simulation to obtain the optimal dimensions. The full-
wave characterization is
employed in the analysis phase to investigate the high
frequency behaviors such as
coupling, dispersion, radiation and surface wave losses. Some
bandpass filters are
fabricated and measured under the TRL calibration. The good
agreement between the
simulation results and experimental data not only validates
the accuracy of the full
-wave characterization approach developed in this dissertation
but also verifies the
proposed design procedures.
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