It is often necessary to operate a number of radio communication
channels from a single control room without time-sharing between the
various channels. Here it is necessary to operate a number of transmitters
and receivers simultaneously from the same base station or
mobile unit without interference. The best method to achieve this
has been found in the use of filters inserted in the transmission line
between the antenna and the transmitter(s) on one hand and the receiver(s)
on the other hand.
The basic unit employed in the design of microwave filters is
usually a cavity resonator of which the most important factors are the
Q, insertion loss and resonant frequency. However, a problem which
frequently arises with cavity resonators is the accurate determination
of these resonant characteristics complicated by the presence of coupling
port, materials and various design and geometrical deviations. Such
cavities have been investigated in several cases and the results have
been generalised, but this investigation has been conducted to examine
thoroughly most of the problems being met in present practice. Design
and development of some common resonant structures are considered.
Emphasis is placed on solutions found to special problems especially
regarding complicated boundary conditions. Furthermore, investigation
includes methods for optimising resonant parameters such as insertion
loss and Q, trading of insertion loss with coupled cavity selectivity,
frequency tuning and compensation for frequency variations due to wide
ranges of operating temperatures. By comparing Q values obtained in
practice with theoretical values, it has been possible to establish an
appropriate Q loss budget to as to facilitate accurate prediction of coupled
cavity unloaded Q. A satisfactory agreement between theory and practice
has been obtained.
By application of the results of theoretical analysis and experiment,
it is shown that microwave filters can be designed to have a desired
insertion loss and off-band attenuation slope. Steps leading to
designs of any number of cascaded cavities in a two-port network and,
subsequently, multi-port networks are discussed in detail.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/3570 |
| Date | January 1984 |
| Creators | Adeniran, S. Adekunle |
| Contributors | Howson, D.P. |
| Publisher | University of Bradford, Postgraduate School of Studies in Electrical and Electronic Engineering |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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