2007 ieee international symposium on electromagnetic compatibility
2007 ieee international symposium on electromagnetic compatibility
2007 ieee international symposium on electromagnetic compatibility
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
18EMC <str<strong>on</strong>g>2007</str<strong>on</strong>g> ADVANCE PROGRAMpredicted the general statistical distributi<strong>on</strong> of the complex reflecti<strong>on</strong>coefficient S11 of a test port c<strong>on</strong>nected to a transmitting antenna, but<strong>on</strong>e measure of the variati<strong>on</strong> was off by a factor of two. We eventuallytraced the increased variability to enhanced backscatter, in whichreflecti<strong>on</strong>s back in the directi<strong>on</strong> of the source antenna tend to be largerthan reflecti<strong>on</strong>s in any other directi<strong>on</strong>. Enhanced backscatter is aphenomen<strong>on</strong> generally associated with remote sensing, especiallyrelated to random media. We give general explanati<strong>on</strong>s of this effectbased <strong>on</strong> a simple ray-optics model.New Hybrid Mode-stirring Technique for Shielding EffectivenessMeasurement of Enclosures Using Reverberati<strong>on</strong> ChambersSandra Greco; and Maria Sabrina Sarto, — University of Rome “LaSapienza”This paper presents a new method for the measurement of the shieldingeffectiveness of “small” enclosures. The technique implements ahybrid mode-stirring technique <strong>on</strong> nested reverberati<strong>on</strong> chambers.The mismatching of the antenna radiating inside the enclosure undertest is taken into account.Sensitivity Analysis of a Reverberati<strong>on</strong> Chamber WithRespect to Tuner SpeedsVignesh Rajamani; Charles Bunting; and James West, — Oklahoma StateUniversityThe energy distributi<strong>on</strong> am<strong>on</strong>g the modes in an overmoded reverberati<strong>on</strong>chamber operating at a particular frequency is studied forvarying tuner speeds. The understanding of this spread is importantin quantifying upsets of equipment in the chamber. The spectralcharacterizati<strong>on</strong> of a time varying <strong>electromagnetic</strong> field is d<strong>on</strong>e usingthe averaged periodogram approach. The complex inserti<strong>on</strong> loss S21is the measured quantity and an estimati<strong>on</strong> of the power inserti<strong>on</strong>loss that will be used in the determinati<strong>on</strong> of Q factor, is obtainedfrom the sampling data for varying angular positi<strong>on</strong>s of the tuner.The same procedure is followed for varying tuner speeds and the Q isreported. The autocovariance for this random process can be foundby taking a Fourier transform of the spectral density functi<strong>on</strong>. Theautocovariance functi<strong>on</strong> helps in determining the number of independentsamples of the field. The field experienced by an EUT in theusable volume due to a c<strong>on</strong>tinuous rotati<strong>on</strong> of the tuner is analyzed.Evaluati<strong>on</strong> of Test Reproducibility of Calibrati<strong>on</strong> inReverberati<strong>on</strong> ChamberJinliang He; R<strong>on</strong>g Zeng; Shuiming Chen; and Bo Zhang, —Electromagnetic Envir<strong>on</strong>ment Research Group; Fan Wu, High Frequency &Microwave Divisi<strong>on</strong>; and Zhiy<strong>on</strong>g Yuan, Electromagnetic Envir<strong>on</strong>mentResearch GroupThe positi<strong>on</strong> of the transmit antenna is analyzed and evaluated accordingto the measurement data in our developed reverberati<strong>on</strong> chamber.The calibrati<strong>on</strong> parameters of the reverberati<strong>on</strong> chamber are also evaluatedfor different working volumes. The key parameters such as theaverage normalized electric field and the receive antenna calibrati<strong>on</strong>factor are analyzed in detail. It is indicated that the definiti<strong>on</strong> of theworking volume and the different positi<strong>on</strong> of the transmit antenna hasa little influence <strong>on</strong> the test reproducibility of calibrati<strong>on</strong>s.REVERBERATION CHAMBER MEASUREMENTS IIAn Investigati<strong>on</strong> of the Shielding Performance of PCB-levelEnclosures using a Reverberati<strong>on</strong> ChamberYuhui He; and Andrew Marvin, — University of YorkPCB-level shielding enclosures differ from the other shielding productsin several aspects due to their small volume and therefore posenew challenges to the evaluati<strong>on</strong> of performance. This paperdescribes several possible approaches and issues about using a reverberati<strong>on</strong>chamber to accomplish a fast and reliable measurement.The interacti<strong>on</strong> between the internal source and the enclosure is alsoinvestigated. In additi<strong>on</strong>, the performance of the enclosure in isolatingnear-field interference in a high-Q envir<strong>on</strong>ment, which is generalin practical applicati<strong>on</strong>s, is compared with the measurement resultfrom the proposed reverberati<strong>on</strong> chamber method. An approach isalso introduced to indicate the impact of changing envir<strong>on</strong>ment tothe near-field coupling.In-situ High Field Strength Testing Using a TransportableReverberati<strong>on</strong> ChamberFrank Leferink, Thales NederlandA reverberati<strong>on</strong> chamber can create a very high field strength withmoderate input power. Existing chambers are making use of a paddlewheel to change the res<strong>on</strong>ant modes in the chamber. In the caseof a stepper motor, the field is stable for some time, and this type ofreverberati<strong>on</strong> chamber is called a mode tuned reverberati<strong>on</strong> chamber.If the paddle wheel is c<strong>on</strong>tinuously rotating we call it a mode stirredreverberati<strong>on</strong> chamber. The mode stirred is much faster in measuringthan the mode tuned, but for some applicati<strong>on</strong>s where theequipment under test has a l<strong>on</strong>g dwell time the mode tuned is preferred.A transportable reverberati<strong>on</strong> chamber with varying anglesbetween wall, floor and ceiling and with vibrating walls has beenused for in-situ testing of a large radar antenna system. Inside thisVibrating Intrinsic Reverberati<strong>on</strong> Chamber (VIRC) a diffuse, statisticallyuniform, <strong>electromagnetic</strong> field is created without the use of amechanical, rotating, mode stirrer. This chamber results in a betterhomogeneity and increased field strength compared to c<strong>on</strong>venti<strong>on</strong>almode stirred reverberati<strong>on</strong> chambers. But the VIRC has a disadvantagebecause it cannot be used for mode tuning. In this paper, aTuneable Intrinsic Reverberati<strong>on</strong> Chamber (TIRC) is presented. Thechamber is still made of flexible material and thus transportable, butthe modes are changed using either a paddle wheel or by moving thewalls in small incremental stepsComparis<strong>on</strong> of Different Definiti<strong>on</strong>s of Field Strength Usedin Reverberati<strong>on</strong> Chamber StandardsLuk Arnaut, Nati<strong>on</strong>al Physical Laboratory; Hans Georg Krauthaueser,Otto-v<strong>on</strong>-Guericke-Universitaet Magdeburg; and Magnus Hoeijer, FOISwedish Defence Research AgencyIn different standards involving reverberati<strong>on</strong> chambers, the fieldstrength is defined either using the vector magnitude (total) electricfield, or the magnitude of a Cartesian (rectilinear) comp<strong>on</strong>ent. Wecompare these methods for determining the maximum field strength.The ratio of the maximum of the total field to the maximum of aCartesian comp<strong>on</strong>ent is a random variable whose probability distributi<strong>on</strong>and statistics are derived and investigated. The mean value of thisratio is compared with the ratio of the respective mean values. Its standarddeviati<strong>on</strong> enables the estimati<strong>on</strong> of c<strong>on</strong>fidence levels when comparingor c<strong>on</strong>verting between single measurements of the maximumtotal and maximum rectangular field. Theoretical results are comparedwith measured results obtained in different reverberati<strong>on</strong> chambers.How to Avoid Unstirred High Frequency Comp<strong>on</strong>ents inMode Stirred Reverberati<strong>on</strong> ChambersOlof Lunden, FOI; and Mats Bäckström, Saab Communicati<strong>on</strong>sA goodness of fit test of the assumed Chi- Squared distributi<strong>on</strong>, ofthe power received by an antenna in a reverberati<strong>on</strong> chamber, is a very©<str<strong>on</strong>g>2007</str<strong>on</strong>g> IEEE www.emc<str<strong>on</strong>g>2007</str<strong>on</strong>g>.org