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Title: The analysis and design of continuous wave metal detectors
Author: Brighton, Mark Andrew.
ISNI:       0000 0001 3480 1007
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 1993
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This thesis is primarily concerned with the design of the type of metal detectors found on industrial production lines such as in the food industry. In paI1icuiar it concentrates on the analysis and design of their search coils. The analysis is restricted to continuous wave detectors, i.e. those which use a constantly alternating magnetic field. The alternative type, which employs a pulsed magnetic field, is mentioned for comparison purposes only. A broad introduction into the physics and technology of present day metal detectors is first presented. This includes some of the real life problems encountered in high sensitivity systems and discusses their various merits in overcoming these difficulties. This is followed by a mathematical analysis of some common coil aITangements hased around the simplified model of a metal sphere. Formulas are delived which predict the received signal strengths and a computer program is introduced which solves this mathematical model. From these, solutions are found for the optimum frequency. coil spacing and number of coil turns. Experimental results are then presented which confirm the theory insofar as the general relations between frequency, sphere size and signal strength. FUl1her experiment<.; also suggest ways in which present coil designs might be improved hy reducing the area around the detector that must be kept clear of metal. Finally, two new coil designs are suggested which are based on both the mathematical and experimental work. Useful extensions to the mathematical model are also suggested which would enable a closer approximation to a real detector set-up.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Solid-state physics