	Practical information Abstract Full text
Royal Military Academy		Université catholique de Louvain
Polytechnic Faculty		Louvain School of Engineering
SIC		ICTEAM
Brussels --- Belgium		Louvain-la-Neuve --- Belgium

Pascal Druyts

kindly invites you to the public defense of his PhD thesis entitled

Analysis of Environmental Effects on Electromagnetic Induction Sensors

The thesis is the fruit of a cotutelle agreement between the Royal Military Academy and the Université catholique de Louvain

Friday 14 October 2011 at 15h00

Symposium room, building I
Royal Military Academy

PhD committee

Supervisors:	Prof. Marc Acheroy, RMA/SIC, Belgium
	Prof. Christophe Craeye, UCL/ICTEAM, Belgium
President:	Prof. Danielle Vanhoenacker-Janvier, UCL/ICTEAM, Belgium
Secretary:	Prof. Xavier Neyt, RMA/SIC, Belgium
Jury:	Dr. Yogadhish Das, DRDC, Canada
	Prof. Ali Khenchaf, ENSTA Bretagne, France
	Prof. Philippe Lataire, VUB/ETEC, Belgium

Practical information

For logistical reasons, please confirm your participation to Pascal.Druyts@elec.rma.ac.be.
The physical entrance of the Royal Military Academy is located 8 Rue Hobbemastraat, B-1000 Brussels. Directions to reach RMA are provided here.
Parking space is available inside the RMA. Please provide me with the registration number of your car. You will need the invitation above to park inside.
Map of the RMA campus

Abstract

Electromagnetic induction sensors are widely used in a number of applications, such as mine clearance, improvised explosive detection, treasure hunting and geophysical survey. Our focus is on pulse induction metal detectors used in the scope of humanitarian demining to detect anti-personnel mines, but most developments remain valid for other applications and for other types of electromagnetic induction sensors. The environment may significantly affect the detection performance of metal detectors. In this thesis, we consider the effect of a magnetic soil, the effect of a water layer on the head of the detector and the effect of the electromagnetic background.

The analysis is based on a detailed model of the detector, including the coil and the fast time electronics. Regarding the soil, a general model is developed, which is valid in the presence of inhomogeneities or soil relief and for an arbitrary head geometry. Then the volume of influence is rigorously defined and computed for typical head geometries. To explain the effect of water on the detector, a rigorous expression for the voltage induced in the coil is established and shows that a coil is sensitive to an electro quasi-static incident field. This contribution is neglected in the so-called classical coil model but in some cases, for example when using some metal detectors over dew grass, it must be taken into account to explain the observed phenomena. Regarding the electromagnetic background, we show that it may affect the detector for frequencies from below 1 Hz to about 20 MHz with a sensitivity peak around 100 kHz.