New Standards for the Validation of EMC Test Sites particularly above 1 GHz

Standards for the validation of alternative test sites with conducting groundplane exist for the frequency range 30-1000 MHz since the end of the eighties. Recently the procedure for fully anechoic rooms (FAR) has been included in CISPR 16 after more than 10 years intensive discussion in standards committees (CENELEC, 2002; CISPR, 2004). But there are no standards available for the validation of alternative test sites above 1 GHz. The responsible working group (WG1) in CISPR/A has drawn up the 7th common draft (CD). A CDV will be published in spring 2005. The German standards committee VDE AK 767.4.1 participates in the drafting of the standard. All suggested measurement procedures proposed in the last CDs have been investigated by measurements and theoretical analysis. This contribution describes the basic ideas and problems of the validation procedure of the test site. Furthermore measurement results and numerical calculations will be presented especially for the use of omni-directional antennas

E-MORB glasses from the Gakkel Ridge (Arctic Ocean) at 87°N: evidence for the Earth's most northerly volcanic activity

During the ARCTIC '91 expedition aboard RV Polarstern (ARK VIII/3) to the Central Arctic Ocean, a box corer sample on the Gakkel Ridge at 87 degrees N and 60 degrees E yielded a layer of sand-sized, dark brown volcanic glass shards at the surface of the sediment core. These shards have been investigated by petrographic, mineralogical, geochemical and radiogenic isotope methods. The nearly vesicle-free and aphyric glass shards bear only minute microphenocrysts of magnesiochromite and olivine (Fo(88-89)). Most glasses are fresh, although some show signs of incipient low-temperature alteration. From their shapes and sizes, the glass shards most likely formed by spalling of glassy rinds of a nearby volcanic outcrop. Geochemically, the glasses are relatively unfractionated tholeiites with E-MORB trace element compositions. Thus, they are quite similar to the previously investigated ARK IV/3-11-370-5 basalts from 86 degrees N. The Nd and Sr isotopic ratios of PS 2167-2 glasses are significantly lower than for ARK IV/3-11-370-5 basalts and suggest an isotopically heterogeneous mantle source of Gakkel Ridge MORE between 86 degrees and 87 degrees N. The positive Delta-8/4 Pb value (similar to 16) and high Sr-87/Sr-86 ratio (0.70270), found for PS 2167-2 glasses are similar to that of ARK IV/3-11-370-5 basalts and show the influence of the DUPAL isotopic anomaly in the high Arctic mantle. These results argue against the presence of an 'anti-DUPAL anomaly' in the mantle below the North Pole region and simple models of whole-mantle convection

Estimation of the threat of IEMI to complex electronic systems

The threat of ultra wideband (UWB) sources is interesting for military issues. This paper summarizes information concerning the voltages generated from some commercially available UWB generator systems and their produced electromagnetic fields. The paper focuses on the coupling of UWB fields into electronic equipment and discusses possible modeling and measurement techniques to estimate such a threat for modern ships. An evaluation procedure for the determination of the induced voltage at the input of an electronic component is presented. This method is based on the computation of the internal electric field and the measurements on a test network, which is similar to the structure of the steering control cabling. It allows the estimation of the potential threat for the ship's electronic equipment due to the exposal to UWB emitting sources

High-Resolution Imaging of Texture and Microstructure by the Moving Detector Method

In order to describe texture and microstructure of a polycrystalline material completely, crystal orientation g={?1F?2} must be known in all points x={x1?x2?x3} of the material. This can be achieved by locationresolved diffraction of high-energy, i.e. short-wave, X-rays from synchrotron sources. Highest resolution in the orientation- as well as the location-coordinates can be achieved by three variants of a detector sweeping technique in which an area detector is continuously moved during exposure. This technique results in two-dimensionally continuous images which are sections and projections of the six-dimensional orientation location space. Further evaluation of these images depends on whether individual grains are resolved in them or not. Because of the high penetration depth of high-energy synchrotron radiation in matter, this technique is also, and particularly, suitable for the investigation of the interior of big samples.researc

Shielding of electronic systems against transient electromagnetic interferences

In order to protect electronic systems against the effects of transient electromagnetic interferences, shields made of electrically conductive material can be used. The subject of this paper is an electrically conductive textile. When applying the shield, a reliable measure is needed in order to determine the effectiveness of the shield to protect against electromagnetic pulses. For this purpose, a time domain measurement technique is presented using double exponential pulses. With these pulses, the susceptibility of an operating electronic device with and without the shield is determined. As a criterion of quality of a shield, the breakdown failure rate found in both cases is compared. © 2004 Copernicus GmbH

Measurement Uncertainty of Radiated Electromagnetic Emissions in In Situ Tests of Wind Energy Conversion Systems

The electromagnetic (EM) emissions of wind energy conversion systems (WECS) are evaluated in situ. Results of in situ tests, however, are only valid for the examined equipment under test (EUT) and cannot be applied to series production as samples, as the measurement uncertainty for in situ environment is not characterized. Currently measurements must be performed on each WECS separately, this is associated with significant costs and time requirement to complete. Therefore, in this work, based on the standard procedure according to the Guide to the Expression of Uncertainty (GUM, 2008) the measurement uncertainty is characterized. From current normative situation obtained influences on the measurement uncertainty: wind velocity and undefined ground are evaluated. The influence of increased wind velocity on the measurement uncertainty is evaluated with an analytical approach making use of the dipole characteristic. A numerically evaluated model provides information about the expected uncertainty due to reflection on different textures and varying values of relative ground moisture. Using a classical reflection law based approach, the simulation results are validated. Thanks to the presented methods, it is possible to successfully characterize the measurement uncertainty of in situ measurements of WECS's EM emissions.</p