Reactive Obstacles In Waveguides
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Background - Project in Electrical & Electronic Engineering At the University of Auckland
It is part of the curriculum that undergraduate final year students at the Department of Electrical & Electronic Engineering, University of Auckland, New Zealand, conduct a one-year project, which is equivalent to a full-year course.
Assessments are made to the following components: An Interim Project Report, Implementation, Demonstration, Seminar and A Project Report.
Introduction to My Project
The project was called Reactive Obstacles in Waveguides and was under the Radio Systems Category. My project partner was Mr. Asanee Suntives and our project supervisor was Professor A. Williamson.
The objective of this project was the development a standard experimental procedure to obtain data on reactive obstacles in waveguides. Measurements were conducted using the advanced HP8510C Microwave Network Analyzer (NWA). Associated software to interface to the NWA had been developed. The program was built using the software LabVIEW. Finally, the system was used to obtain data for some common engineering scenarios.
What Are Waveguides?
At frequencies higher than 3 GHz, transmission of electromagnetic waves along lines and cables becomes difficult. This is because of the losses in the solid dielectric needed to support the conductors, and in the conductors themselves. Therefore, usually, waveguides in the form of hollow metallic tube are used to convey signal at microwave frequencies.
What Are Waveguide Components?
Modern communications and radar antenna systems employ a number of different waveguide components. They change or control the characteristics of the carrier. Typical examples of microwave components are filters, matching networks, directional couplers, polarizers, orthomode transducers, phase shifters, circulators, isolators and switches.
What Are Reactive Obstacles?
Fundamentally, at microwave frequencies, filters and matching networks are often constructed using reactive obstacles and discontinuities in waveguides. These elements produce reflections, and hence change the propagation characteristics of the electromagnetic wave. A simple way to implement such a system is by inserting a variable length of metal post into the broad side of the waveguide. By varying the position and the insertion depth of the post, different electrical characteristics can be achieved.
Since these obstalces are highly electrically conductive, ohmic losses are negligible. Therefore electrical effects are introduced while no energy loss takes place. This electrical property is termed reactive.
Highlights of My Project
I tended to categorize this project as one with a heavy research emphasis. Asanee and I completed the modeling and the derivation of a set of unique mathematical formulae, tailored for the proposed experimental procedure.
Regarding the objectives of this project, all of the requirements had been fulfilled.
Furthermore, the project had earned us the following two Awards:
(1) Year 4 Project Prize for Radio Systems - sponsored by Digial Microwave Ltd., Wellington.
(2) Year 4 Project Prize for Best Poster - sponsored by the Institute of Electrical & Electrical Engineers(IEEE), New Zealand North Section.
Final Project Report
The findings, conclusions and recommedations of the project was summarised in this 70-page report. Click to read the Online Version of the Final Project Report.
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