title: Human exposure assessment in the near field of GSM base-station antennas using a hybrid finite element/method of moments technique.
abstract: A hybrid finite-element method (FEM)/method of moments (MoM) technique is employed for specific absorption rate (SAR) calculations in a human phantom in the near field of a typical group special mobile (GSM) base-station antenna. The MoM is used to model the metallic surfaces and wires of the base-station antenna, and the FEM is used to model the heterogeneous human phantom. The advantages of each of these frequency domain techniques are, thus, exploited, leading to a highly efficient and robust numerical method for addressing this type of bioelectromagnetic problem. The basic mathematical formulation of the hybrid technique is presented. This is followed by a discussion of important implementation details-in particular, the linear algebra routines for sparse, complex FEM matrices combined with dense MoM matrices. The implementation is validated by comparing results to MoM (surface equivalence principle implementation) and finite-difference time-domain (FDTD) solutions of human exposure problems. A comparison of the computational efficiency of the different techniques is presented. The FEM/MoM implementation is then used for whole-body and critical-organ SAR calculations in a phantom at different positions in the near field of a base-station antenna. This problem cannot, in general, be solved using the MoM or FDTD due to computational limitations. This paper shows that the specific hybrid FEM/MoM implementation is an efficient numerical tool for accurate assessment of human exposure in the near field of base-station antennas.
authors.affiliation: EM Software & Systems SA, Technopark, P.O. Box 1354, Stellenbosch 7600, South Africa. fjcmeyer@emss.co.za
authors.forename: Frans J C
authors.initials: FJ
authors.lastname: Meyer
authors.forename: David B
authors.initials: DB
authors.lastname: Davidson
authors.forename: Ulrich
authors.initials: U
authors.lastname: Jakobus
authors.forename: Maria A
authors.initials: MA
authors.lastname: Stuchly
mesh_terms: D040421:Cell Phone; D003198:Computer Simulation; D020342:Finite Element Analysis; D006801:Humans; D008954:Models, Biological; D009928:Organ Specificity; D011829:Radiation Dosage; D011830:Radiation Effects; D011834:Radiation Monitoring / Q000379:methods; D011846:Radio Waves; D011874:Radiometry / Q000379:methods*; D012680:Sensitivity and Specificity; D014916:Whole-Body Irradiation / Q000379:methods*