Time filter

Source Type

Kamp-Lintfort, Germany

Bornkessel C.,IMST GmbH | Blettner M.,Johannes Gutenberg University Mainz | Breckenkamp J.,Bielefeld University | Berg-Beckhoff G.,Bielefeld University
Radiation Protection Dosimetry

In the framework of an epidemiological study, dosemeters were used for the assessment of radio frequency electromagnetic field exposure. To check the correct dosemeter's performance in terms of consistency of recorded field values over the entire study period, a quality control strategy was developed. In this paper, the concept of quality control and its results is described. From the 20 dosemeters used, 19 were very stable and reproducible, with deviations of a maximum of ±1 dB compared with their initial state. One device was found to be faulty and its measurement data had to be excluded from the analysis. As a result of continuous quality control procedures, the confidence in the measurements obtained during the field work was strengthened significantly. © The Author 2010. Published by Oxford University Press. Source

Pohl N.,Ruhr University Bochum | Klein T.,IMST GmbH | Aufinger K.,Infineon Technologies | Rein H.-M.,Ruhr University Bochum
IEEE Journal of Solid-State Circuits

A low-power FMCW 80 GHz radar transmitter front-end chip is presented, which was fabricated in a SiGe bipolar production technology (f T=180 GHz, f max=250 GHz). Additionally to the fundamental 80 GHz VCO , a 4:1-frequency divider (up to 100 GHz), a 23 GHz local oscillator (VCO) with a low phase noise of -112 dBc/Hz (1 MHz offset), a PLL-mixer and a static frequency divider is integrated together with several output buffers. This chip was designed for low power consumption (in total < 0.5 W, i.e., 100 mA at 5 V supply voltage), which is dominated by the 80 GHz VCO due to the demands for high output power (≈ 12 dBm) and low phase noise (minimum -97 dBc/Hz at 1 MHz offset) within the total wide tuning range from 68 GHz to 92.5 GHz (Δ f= 24.5 GHz). Measurements of the double-PLL system at 80 GHz showed a low phase noise of dollar;-88 dBc/Hz at 10 kHz offset frequency. © 2012 IEEE. Source

Kunisch J.,IMST GmbH
Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012

The purpose of this paper is to give an overview on some types of hypercomplex numbers and to stimulate a discussion on their possible uses for e.m. problems. As an application example related to antennas and propagation, the determination of the complex amplitude gain of an antenna using the three-antenna method is discussed. It is shown how a formulation in terms of vectors and matrices can be interpreted using hypercomplex numbers. © 2012 IEEE. Source

Thumm M.,Karlsruhe Institute of Technology | Kasparek W.,University of Stuttgart | Wagner D.,Max Planck Institute for Plasma Physics (Garching) | Wien A.,IMST GmbH
IEEE Transactions on Antennas and Propagation

Reflection of circular symmetric TE0n modes (n= 1-6) at an oversized, open-ended circular waveguide (C76-waveguide, inner diameter=27.79 mm, 70 GHz) radiating into free space has been investigated theoretically employing two scattering matrix codes (SMCs), the finite-difference time-domain code EMPIRE and the uniform geometrical theory of diffraction (UTD) as well as the first time experimentally. The measurements utilized mode converters for generation of pure TE0n modes and a wavenumber spectrometer for mode analysis in the oversized waveguide. The total power reflection computed by EMPIRE is 4.1 to 13.4 dB lower than calculated from free-space wave and waveguide mode impedances. In all cases, most of the reflected power is carried by the backward traveling TE06 mode, which is the mode closest to cutoff. Experiments are in very good agreement with theoretical results. © 1963-2012 IEEE. Source

Bornkessel C.,IMST GmbH
Wiener Medizinische Wochenschrift

Typical general public exposures around mobile radio service base stations consume only tiny fractions of exposure levels. Maximal immissions at maximal transmit power of base stations amount to several percent of power density reference levels; typical immission levels are about one tenth of a percent or even less. The distance to base stations is no reliable exposure classifier. More important are the orientation relative to the main lobe of the station and sight conditions from measurement point to the base station. Mobile phones cause higher exposures to the user than base stations. At maximal transmit power up to 80 percent of the basic restrictions are consumed. Therefore, actions to minimize exposure to mobile phones, e.g. by using a headset, have a larger potential than shielding against emissions from base stations. Both base stations and mobile phones apply power control mechanisms, capable to significantly reducing the transmit power and the associated exposure depending on the communication traffic. Present research investigates, whether children are more exposed to mobile telecommunication systems than adults. © 2011 Springer-Verlag. Source

Discover hidden collaborations