Reconstruction of Internal Field of Dielectric Objects for Noninvasive SAR Measurement Using Boundary Integral Equation

• Published in: IEEE transactions on electromagnetic compatibility Vol. 61; no. 1; pp. 48 - 56
• Main Authors: Omi, Shuntaro, Uno, Toru, Arima, Takuji, Wiart, Joe
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-02-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Antenna measurements; Boundary integral method; Dielectric measurement; Dielectrics; Dipole antennas; electromagnetic (EM) fields; Engineering Sciences; Equivalence; Integral equations; inverse problems; Lossless materials; Phantoms; Probes; Reconstruction; specific absorption rate (SAR); Surface impedance; Surface reconstruction; Antenna measurements; specific absorption rate (SAR); Surface reconstruction; Surface impedance; integral equations; Phantoms; inverse problems; Dielectric measurement; Dielectrics; Probes; electromagnetic (EM) fields
• DOI: 10.1109/TEMC.2018.2813398
• EISSN: 1558-187X
• ISSN: 0018-9375

Reconstruction of the electromagnetic (EM) fields inside a dielectric object is investigated in order to develop a noninvasive specific absorption rate measurement. The proposed reconstruction method is based on the boundary integral equation (BIE) derived from the surface equivalence theorem that relates the equivalent EM currents on the surface enclosing the primary source to the radiated external fields. The EM currents are reconstructed by solving the discretized BIE using the field data sampled on the surface surrounding all of the target objects that consist of the dielectric phantom and radiating antenna. The field distribution inside the dielectric object is obtained from the reconstructed currents. A probe correction technique is also proposed to enable the application of this method to practical probe measurements. As the first step to the practical applications, the validity and usefulness of the proposed method are demonstrated numerically and experimentally using lossless and lossy homogeneous dielectric objects located near a dipole antenna, respectively. It is shown that the accuracy tends to deteriorate in the case of the lossy phantom, but this can easily be improved without significant modification of the proposed method.