Forschungsgemeinschaft Funk e.V.

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Edition No. 12b December 1996
HF-Design of a Measurement Setup for the Investigation of Cerebro- Biological Effects in Low-Frequency Pulsed RF Fields

Prof. Dr.-Ing. V. Hansen, Dipl.-Ing. Th. Eibert,
Dipl.-Ing. H. Kammerer, Dipl.-Ing. Th. Vaupel,
Bergische Universität-Gesamthochschule Wuppertal,

The described work is in close relationship to the study “Cerebro-biological Effects in Low-Frequency Pulsed RF Fields” [1] initiated by the Forschungsgemeinschaft Funk e.V. The purpose of this study was to investigate whether the electromagnetic fields of mobile telephones cause cerebro-biological effects. The intensities of the fields should be relatively low to avoid the occurence of thermal effects. To assure that the results are reproducible in the sense of a scientific work, special attention was given to the HF-design of the investigation methods, what is described in this paper. The exposition field was produced with a commercial mobile telephone. The output power of the telephone and the magnitude of the electric field strength in terms of the distance to the antenna of the telephone were measured. According to these results the distance between the head of the test person and the antenna was adjusted to about 45cm to assure that the limit value according to DIN/VDE 0848, expostion condition 2 could not be exceeded. Numerical simulations of the test room showed that it was necessary to equip the room with HF-absorbers in order to achieve a reproducible field distribution in the room. External parasitic fields were measured and recorded in the frequency range of 5Hz to 3GHz. The strongest identified parasitic sources were public and local radio transmitters. The highest field strenths up to about 25mV/m were magnitudes smaller than the exposition field strength of about 40V/m. By an analysis of the EEG-signals small distortions of the signals due to the exposition field were found. The distortions could effectively be suppressed by the choice of an appropriate sampling rate of 500Hz for the digital evaluation of the EEG-signals.

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