IEEE Conference Proceedings

Hahner, T.; Mund, B.; , "EMC-performance of balanced (symmetrical) cables," Screening Effectiveness Measurements (Ref. No. 1998/452), IEE Colloquium on , vol., no., pp.8/1-8/7, 6 May 1998 S.^/Cl;aj  
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doi: 10.1049/ic:19980731 Wzm!:U2R*  
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Abstract: The frequency range of balanced pairs or quads, e.g. for horizontal floor wiring for data communication has increased up to the GHz range. Especially in this field of data transmission a high screening effectiveness and a good EMC behaviour of such cables is required. In order to measure the EMC-behaviour of these cables, new measuring procedures have been developed which are under discussion for international standardisation. The screening effectiveness of screened balanced pairs is the sum of the unbalance attenuation of the pair and the screening attenuation of its screen which is described as the coupling attenuation. With the new triaxial measuring procedure and its measuring tube in accordance to IEC 46A/320/CDV the screening attenuation of the screen and the coupling attenuation of the complete cable can be measured. The difference of the coupling attenuation and the screening attenuation is the unbalance attenuation. In this way the unbalance attenuation of balanced cables may be measured up to the GHz range with baluns without a centre tap {:peArO  
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URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=710509&isnumber=15409 o3=2`BvJ  
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Halme, L.; Kytonen, R.; , "Background and introduction to EM screening (shielding) behaviours and measurements of coaxial and symmetrical cables, cable assemblies and connectors," Screening Effectiveness Measurements (Ref. No. 1998/452), IEE Colloquium on , vol., no., pp.4/1-428, 6 May 1998 luPj'd?  
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doi: 10.1049/ic:19980727 1$A7BP  
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Abstract: The theory and related parameters of screening (shielding) are identified and behaviour explained. The concepts of the square root of power waves, general coupling functions and operational attenuation are introduced. The coupling mechanisms between parallel lines are explained and the influence of cable (coupling) lengths and frequencies is outlined and a summing function envelope called screening attenuation introduced. Theoretical curves with different cable screening parameters are shown. The mechanism of the leakage of a single braid is explained and shows that a perforated tube cannot be used as a model for a braided screen. The advantages and shortcomings of 16 different test methods of screen have been stated. Some preliminary statements of the measurement of the coupling attenuation of balanced cables are made. It seems to be an agreement between screening specialists that ITU-T Recommendation G 117 [32 ITU-T] could be used as definitions and principal measurement set-ups for the symmetry to earth of balanced cable pairs also in the 100s of MHz transmission region. Since both screening attenuation and coupling attenuation are dependent on measurement set-ups the results have to be measured in standardised conditions or test results have to be reduced to standardised conditions. However, it is recommended that both series of test results are given to avoid mis .. V~tZNRJ-  
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