The objective of this project is to design an antenna for use in the electronic monitoring
of persons convicted of non-violent crimes. If implemented, electronic monitoring will
lighten the load on the South African prison system. Electronic monitoring makes use
of an electronic tether connected to the person being monitored. This led to specific
performance requirements and size constraints being placed on the antenna. The antenna
should be physically small while still being able to perform as specified. It is
also necessary to test the design with various frequencies, to determine the best possible
frequency to use.
It was decided to use a Transformer Coupled Loop (TCL) antenna, after various designs
were considered. The TCL antenna can be used in various configurations, with
some of these configurations being simulated to determine the best antenna structure
to use. After various antenna structures were discarded, a specific antenna structure
emerged as a possible solution, which was then optimised to deliver the best possible
performance.
The optimised antenna model was constructed to test the antenna performance. The
receiving antenna was a directional Log-Periodic Dipole Antenna (LPDA), connected
to a spectrum analyser. Tests were conducted in an open-field environment to minimise
the effect of reflections. The azimuth- and elevation radiation patterns for the
antenna could be compared to the simulated results. The same tests were performed
with the antenna attached to a saline solution bag, simulating the effects of the human
body on the antenna performance.
The radiation patterns obtained from the measured results proved to be similar to the
simulated results for both frequencies tested. When making use of the human analogue,
the radiation pattern tended to be more omnidirectional in both the azimuthand
elevation planes. These results are ideal, since omnidirectional communication by
the tethering device is required by a security application. The primary objective was
achieved, together with the secondary objectives of comparing different frequencies. / Thesis (M.Ing. (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2012
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/11749 |
| Date | January 2011 |
| Creators | Thom, Carl Friedrich |
| Source Sets | North-West University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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