Information Technology (INTEC)

A measurement setup and calibration procedure are described allowing the accurate on wafer measurement of phases and amplitudes of the spectral components of incident and scattered voltage waves at the signal ports of a nonlinear microwave device. A comparison is made between measurements performed with the setup and simulations based on a Root-model.>

The use of frequency-selective measurements for the assessment of the worst-case exposure to electromagnetic fields radiated by GSM base stations is widely accepted to check the compliance with the existing regulations when multiple frequency sources are present. In this paper, the influence of different settings of the spectrum analyzer (resolution bandwidth, sweep rate, and detector) on the accuracy of power measurements has been studied with simulations by using a simple model for the spectrum analyzer and the global system for mobile communications (GSM) signal. The effect of adjacent frequency channels, time modulated signals, and down link power control have been investigated. Based on the obtained simulation results, optimal spectrum analyzer settings have been proposed for the exposure assessment around GSM base stations. As a final result, the accuracy of the proposed optimal settings for the spectrum analyzer has been determined.

A new and fast numerical method is presented to assess the whole-body averaged specific absorption rate (SAR) in a human body model in a realistic electromagnetic environment. The method requires a minimum set of initial numerical simulations with a 3D electromagnetic solver. From the initial simulation results, the absorption can be quickly (within 1 s) determined in a realistic electromagnetic environment. The realistic electromagnetic environment has been modeled as a finite sum of incident plane waves. The presented fast method serves as a substitute for brute-force 3D electromagnetic simulations. Therefore, the method must only be validated with brute-force 3D electromagnetic simulations in terms of whole-body averaged SAR, and excellent agreement has been observed. The method has been applied to assess the cumulative distribution function of the whole-body averaged SAR in a spheroid human body model for four types of realistic electromagnetic environments. We observed that for all the four environments the whole-body averaged SAR complies with the International Commission on Non Ionizing Radiation Protection basic restriction for general public. Furthermore, the whole-body averaged SAR for a realistic exposure exceeds the worst-case single plane wave exposure in approximately 10% of the exposure samples. Health Phys. 94(4):345-354; 2008

Three-dimensional electromagnetic calculations for loaded transverse electromagnetic (TEM) transmission cells are presented . Based on those calculations a prediction of the perturbation of the standard uniform field in the TEM-cell, due to the scattering by inhomogeneous structures placed inside the cell cavity, is given . The influence of the dimensions of a lossy structure and its position in the TEM-cell on its absorption of the electromagnetic fields is presented . Knowing the perturbation of the uniform field is important for good interpretation of the biological experimental results .

The shielding performance of an infinitely large, periodically perforated plane shield is investigated, both theoretically and experimentally. Attention is focused upon the near-field characterization by using two loop antennas at both sides of the shield. The electromagnetic coupling between the two loops is analyzed numerically using a plane-wave spectral representation of the radiated field and the method of moments. Comparison of these numerical results with near-field measurements yields a very good agreement up to high frequencies. The predicted classical far-field shielding effectiveness drastically overestimates the near-field shielding performance of the screen

Fixed wireless access systems operating below 11 GHz have the potential to provide broadband wireless access for non line-of-sight operation. In this paper the performance of a typical broadband fixed wireless system based on the IEEE 802.16-2004 specifications is determined. A scenario for business applications with outdoor customer premises equipment is investigated in the 3.5 GHz frequency band. Different path loss models and terrain types are considered. Coverage and throughput in a sector are determined for this business scenario