RF/microwave terrestrial point-to-point and satellite communication systems employ
a large number of waveguide components operating at microwave and millimeter
wave frequencies. Accurate design of these components for optimum performance
of the overall system is critical. To achieve this, computationally efficient and accurate numerical methods are indispensable tools in the design and optimization of
components and subsystems.
Among the large variety of potentially suitable numerical methods, the mode
matching method in conjunction with the generalized scattering matrix technique
has been found to be one of the most reliable and straightforward techniques to
design waveguide components. In the past the method has been mainly applied to
eigenvalue and scattering problems in rectangular waveguides. In this thesis, the mode
matching method is extended to ridge waveguide problems in circular waveguides and
thus closes a gap in the literature that has existed for a long time.
The thesis begins with a study of the basic principles of the mode matching method
as it is known from rectangular waveguides. These principles are then applied to the
analysis of the rectangular ridged and coaxial waveguide, followed by an eigenvalue
analysis of ridged circular waveguide. Rather than rectangular ridges, ridges of uniform
angular thickness (conically shaped) are used in the circular waveguide to avoid
a mixed coordinate system which would render the mode matching method computationally very inefficient. On the other hand, conically shaped ridges are as easy to
fabricate as rectangular ridges and are not detrimental to the electrical performance
of the component.
The thesis then continues to treat the discontinuity problem at the interface between the empty circular waveguide and ridged circular waveguide. To verify the
computed scattering parameters, measurements were performed and good agreement
was found. By cascading several discontinuities transformers and evanescent mode
filters were designed. A fifth order filter was designed and fabricated and also here
good agreement between measured and computed data was found.
The final chapter in the thesis analyses the coupling between orthogonal modes in
the presence of an asymmetric discontinuity. Determining the coupling factor between
orthogonal modes is an integral part of the design of polarizers and dual mode filters
and for conically shaped ridges, has not been published in the open literature yet.
To realize various coupling coefficients, a single or double ridges must be placed at
an arbitrary angle to the exciting wave. The mode matching method is extended to
include also this case and various convergence tests have been performed to validate
the algorithm . As a final example, the algorithm has been applied to design a circular
polarizer with two ridges.
Although only two-port problems are treated in this thesis, the basic framework
for the mode matching method in circular waveguide has been established and can
now be extended to three-port problems. This will be the subject of future work to
analyze and design power dividers and orthomode transducers. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/9798 |
| Date | 31 July 2018 |
| Creators | Balaji, Uma |
| Contributors | Vahldieck, Rùˆdiger |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
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