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Reverberation Chamber (reverberation + chamber)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

Active measurements of antenna diversity performances using a specific test-bed, in several environments

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2010
Moctar Mouhamadou
Abstract The diversity performances of the wireless devices operating in a multipath propagation environment are usually presented in terms of correlation coefficient, diversity gain and effective diversity gain. These parameters can be measured in reverberation chamber. This paper presents some active measurements of antenna diversity performances on a small wireless terminal in several realistic environments. The measurements were performed in the WiMax band, i.e. at 3.5 GHz, in a reverberation chamber where the channel is statistically uniform, in a real indoor propagation channel, and in an outdoor-to-indoor environment. The diversity performances are evaluated by using a specific test-bed constituted by an arbitrary signal generator and two radio-frequency digitizers. The effectiveness of diversity is presented in terms of effective diversity gain, signal to noise ratio, bit error rate and frame error rate. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [source]

Active measurements of a mimo WiMAX-OFDM based system in reverberation chambers

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2010
Adil Belhouji
Abstract Electromagnetic reverberation chambers can be used for multiple-input multiple-output (MIMO) systems testing.Currently, the tests focus on parameters such as correlation, diversity gain, efficiency, etc., by using a vector network analyzer. In contrast with these passive tests, a novel way of MIMO systems characterization is described in this article. It consists on evaluating bit error rate (BER) levels of a MIMO WiMAX-OFDM system according to the Signal-to-Noise Ratio (SNR) by establishing an active link between the transmitter and the receiver. The measurement process is set up in a reverberation chamber, where multipath frequency selective channels are emulated. The obtained results are compared to a reference case with single-input single-output (SISO) to evaluate the real improvements made by the studied system. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2347,2352, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25465 [source]

Definition of effective diversity gain and how to measure it in a reverberation chamber

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2002
Per-Simon Kildal
Abstract The performance of cellular phones and other mobile or wireless terminals operating in multipath propagation environment can be greatly improved by introducing different diversity schemes. The improvement is characterized in terms of a diversity gain. An effective diversity gain is defined here. This is an absolute measure of diversity gain and can therefore be used to compare different diversity antennas. The Letter also shows how the effective diversity gain can be measured in a reverberation chamber. Measured effective diversity gains agree much better with theoretical diversity gains than measured values published previously. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 56,59, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10372 [source]

Die neue Tonhalle Düsseldorf , Beratung einer akustischen Quadratur des Kreises

BAUPHYSIK, Issue 3 2006
Klaus-Hendrik Lorenz-Kierakiewitz Dipl.-Phys.
In diesem Aufsatz wird ein Überblick über die mannigfaltigen Facetten einer nichtalltäglichen raumakustischen Beratung gegeben: der kompletten Modernisierung der aufgrund Ihrer Form echobehafteten Tonhalle Düsseldorf, welche nach intensiver Planung und Beratung am 4. November 2005 mit großem Erfolg neu eröffnet werden konnte. Durch umfangreiche Labormessungen in einem akustischen Maßstabsmodell, einem reflexionsarmen Raum und einem Hallraum konnten hierzu spezielle Reflektorgeometrien, akustisch transparente Metallgewebe, eine minimal absorbierende Bestuhlung und nahezu geräuschlose architektonische Beleuchtungskörper entwickelt werden, womit nicht nur das frühere Echoproblem gelöst, sondern auch ein State of the Art-Konzertsaal mit hervorragender Akustik und beeindruckender Optik gebaut werden konnte. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) The new Tonhalle Düsseldorf , acoustically consulting of squaring a circle. In this paper an overview is given over the many sides of an unusual consulting project: the complete refurbishment of the Tonhalle Düsseldorf, which suffered formerly from severe echoes caused by its half-spherical shape. This concert hall could be re-opened on 4th November, 2005 with great success. By help of comprehensive laboratory measurements in an acoustical scale model, in a reflection-damped and in a reverberation chamber, specialized reflector geometries, acoustically transparent metal texture, minimally absorbing chairs and almost noiseless architectural lighting could be developed. With help of these measures, not only the former echo-problem could be solved, but also a state-of the-art concert hall with great acoustics and visual impression could be built. [source]