Complex source modeling for electromagnetic dosimetry
Licentiatavhandling, 2008

Electromagnetic modeling of complex sources is useful in dosimetry applications as well as for near-field to far-field transformations and antenna diagnostics. In order to determine whether exposure safety guidelines, such as the EU directive 2004/40/EC, are complied with, it is important to be able to model the field distribution from electromagnetic sources. Two methods of determining the total field, including phase information, when only field amplitudes have been measured on a set of planes in front of an electromagnetic source have been developed. The first method, the adjoint field method, is a gradient based optimization algorithm based on the adjoint fields. The second method, the phase angle gradient method, employs an optimization algorithm based on the phase angle gradients of a functional. The methods have been tested with numerical test cases. The adjoint field method is functioning well in 2D and the phase angle gradient method gives good results for 3D test cases. The phase angle gradient method was also tested for measured magnetic flux density with low frequency from a transformer and for electric field with high frequency from a mobile phone. For the cases with measured field the obtained phase angles on the measurement plane closest to the source gave calculated field on other measurement planes that agrees well with measured field. The developed methods are useful for coupling of measured field amplitudes in front of a source, to numerical calculations of the fields inside humans.

optimization

phase-retrieval

source modeling

dosimetry

SAR

Room EA, Hörsalsvägen 11, Chalmers
Opponent: Senior Research Engineer Jonas Fridén, Antenna Research Center, Ericsson Research, Sweden.

Författare

Markus Johansson

Chalmers, Signaler och system, Signalbehandling och medicinsk teknik, Biomedicinsk elektromagnetik

Computational methods for modeling of complex sources

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering,; Vol. 27(2008)

Artikel i vetenskaplig tidskrift

Ämneskategorier

Biofysik

Annan elektroteknik och elektronik

Room EA, Hörsalsvägen 11, Chalmers

Opponent: Senior Research Engineer Jonas Fridén, Antenna Research Center, Ericsson Research, Sweden.