In this paper transient electromagnetic wave propagation in a stratified, anisotropic, dispersive medium is considered. Specifically, the direct scattering problem is addressed. The dispersive, anisotropic medium is modeled by constitutive relations (a 3 × 3 matrix-valued susceptibility operator) containing time convolution integrals. In the general case, nine different susceptibility kernels characterize the medium. An incident plane wave impinges obliquely on a finite slab consisting of a stratified anisotropic medium. The scattered fields are obtained as time convolutions of the incident field with the scattering kernels. The scattering (reflection and transmission) kernels are uniquely determined by the slab and are independent of the incident field. The scattering problem is solved by a wave splitting technique. Two different methods to determine the scattering kernels are presented; an imbedding and a Green functions approach. Explicit analytic expressions of the wave front are given for a special class of media. Some numerical examples illustrate the analysis.

An inverse medium scattering problem for a homogcnwus slab of anisotropic dispersive medium is presented. The inverse problem is to recover the dyadic susceptibility kernel from the dyadic reflection kernels for obliquely incident transient electromagnetic plane waves. A time domain technique, based on wave splitting and invariant imbedding, is used, Mirror images enter into the fomalism in a natural way and are therefore discussed.This leads to a simplified problem for a class of mirror image symmetric media. This is solved numerically and the stability of the algorithm is tested using noisy data.

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In this paper, different methods for practical numerical radio frequency (RF) exposure compliance assessments of radio base station (RBS) products are investigated. Both multi-band base station antennas and antennas designed for multiple-input multiple-output (MIMO) transmission schemes are considered. For the multi-band case, various standardized assessment methods are evaluated in terms of resulting compliance distance with respect to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels and basic restrictions. Both single frequency and multiple frequency (cumulative) compliance distances are determined, using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 MHz and 2600 MHz. The assessments are conducted in terms of the root-mean squared electromagnetic field, the whole-body averaged SAR and the peak 10g averaged SAR. In general, assessments based on peak field strengths are found to be less computationally intensive but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. As long as adult exposure is considered, the results also indicate that even shorter compliance distances are obtained by using assessments based on localized and wholebody SAR. Numerical simulations, using base station products employing multiple-input multipleoutput (MIMO) transmission schemes, are performed as well and are in good agreement with reference measurements. The applicability of various field combination methods for correlated exposure is investigated, and best estimate methods are proposed. It is also shown, that field combining methods generally considered as conservative may be used to efficiently assess compliance boundary dimensions of single-and dual-polarized multicolumn base station antennas with only minor increases in compliance distances. Key words: Mobile communication; Electromagnetic field exposure; EMF compliance; SpecificAbsorption Rate; MIMO; Multi-standard radio base station; Multi-band radio base station. INTRODUCTIONBefore radio base station (RBS) products are placed on the market, their manufacturers conduct electromagnetic field (EMF) product compliance assessments to make sure that the equipment fulfills relevant regulatory requirements on EMF exposure. The purpose of these assessments is to determine compliance boundaries outside of which the radiofrequency (RF) EMF exposure is below applicable exposure limits. The most widely adopted exposure limits are specified by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [ICNIRP, 1998]. For frequencies between 10 MHz to 10 GHz, including the frequency range used for mobile communications, the fundamental dosimetric quantity is the specific absorption rate (SAR). SAR corresponds to the rate of dissipated energy per unit mass within the exposed body due to the incident electromagnetic fields. Assessing exposure with respect to the basic re...