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Measuring of EMC Characteristics on Cables for Information & Communication Technics Mess-System CoMeT bedea Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 1


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Measuring of EMC Characteristics on Communication Cables Author: Bernhard Mund, Radio&TV Technician, Radio Brand, Marburg, 1971 Dipl.-Ing. Nachrichten- & Mikroprozessortechnik, FH Giessen 1984 bedea Berkenhoff&Drebes GmbH, Asslar since 1985 bedea Manufacturer of Communication Cables, (CATV-Kabel) Responsible: R&D Manager, RF- und EMC-Measurements, Standardisation: Chairman of UK 412.3, Koaxialkabel, (German NC) Secretary of IEC SC 46X, Coaxial cables Secretary of CENELEC SC 46XA, Coaxial cables Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 2


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Outline Physical Basics of Cable Screening Definitions, elektrical length Coupling Transfer Function Measuring of the Screening of Cables Transferimpedance & Screening attenuation Coupling attenuation Further Developments Screening of Connectors & Connecting Hardware Conclusion & Discussion Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 3


Measuring of EMC Characteristics on Cables for Information & Communication Technics Definitions, electrical length bedea high frequencies: Screening attenuation a S = 10 log (P 1 /P 2 ) = 20log 10 (U 1 /U 2 ) [dB] Ratio of two powers --> length independent low frequencies: Transferimpedance electrical long: co f Wave length λ = (c 0 • v k ) / f ⋅l ⋅ ε r1 − ε r2 I 2 U 1 l < λ/10 I 2 Z = T U I 2 1 [mΩ/m] > 2 r1 electrical short: c f < 10 ⋅ l ⋅ o ε (EN 50289-1-6) Ratio of U/I = R --> length dependent (Ohms law) Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 4


Measuring of EMC Characteristics on Cables for Information & Communication Technics Coupling between two lines bedea near end P 2n Disturbed line (surrounding) P 2f far end Z 2n U 2n Z 2 , ε r2 , v 12 , γ 2 U 2f Z 2f receiver reversible Z 1n U 1n U 1f Z 1f Z 1 , ε r1 , v 1 , γ 1 generator P 1n disturbing line Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 5


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Summing function S nf (l • f) cn (l • f) cf far 1 S n f = ⎛ 2 sin⎜ ⎝ ( β ( β ± β ) 1 1 ± β 2 2 2 ).L .L c c ⎞ ⎟ ⎠ ≈ sin x/x 0,1 low frequencies near S n f →1 0,01 1,E+07 1,E+08 1,E+09 1,E+10 high frequencies Sn f → ( β 1 2 ± β 2 ) ⋅l Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 6


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Calculated Coupling Transfer Function T nf a s and Z T vs frequency T s, n f = ( Z ± Z ) F T ⋅ Z 1 1 ⋅ Z 2 l ⋅ ⋅S 2 n f dB T f Tn n = near end f = far end L = 1 m ε =2,3 r1 ε r2 = 1,0 Z =0 F 10 kHz 100 kHz 1 MHz 10 MHz fcf 1 GHz 10 GH Transferimpedance fcn Screening attenuation frequency Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 7


Measuring of EMC Characteristics on Cables for Information & Communication Technics Measuring with the Triaxial test set-up CoMeT bedea Transferimpedance & Screening attenuation few kHz up to and above 3 GHz with one test set-up generator screen under test tube matching resistor receiver screening cap IEC 61196-1, A1 Generic for RF-Cables, EN 50289-1-6, EMC on Communication cables Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 8


Measuring of EMC Characteristics on Cables for Information & Communication Technics Measured Transfer function of RG 058 bedea Transferimpedance Screening attenuation -40 -50 -60 as/[dB] -70 -80 -90 -100 0,1 1 10 100 1000 10000 frequency f/[MHz] Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 9


Measuring of EMC Characteristics on Cables for Information & Communication Technics Transferimpedance Telass 110 in mOhm/m bedea Kopplungswiderstand Telass 110 0 1 2 3 4 5 6 7 8 9 0,1 1 10 100 3,5 mΩ/m @ 5 MHz Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 10


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Diiferential & Common mode of a balanced pair Z S U Sn Common mode Gleichtaktbetrieb Z S U Sf (coaxial) (symmetrical) U Un Z u U Uf Z u Differential mode Gegentaktbetrieb Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 11


Measuring of EMC Characteristics on Cables for Information & Communication Technics Measuring of Coupling attenuation bedea Coupling attenuation is the sum of Unbalance attenuation of the pair and the Screening attenuation of the screen generator DUT tube symmetric/ asymmetric load balun screening cap receiver IEC/PAS 62338 Ed1, Coupling attenuation, triaxial method Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 12


Measuring of EMC Characteristics on Cables for Information & Communication Technics Coupling attenuation of a CAT 6 Cable, S/FTP, log scale, Triaxial set up bedea 50 dB 70 90 110 130 150 1 10 100 1000 f / MHz Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 13


Measuring of EMC Characteristics on Cables for Information & Communication Technics Triaxial set-up with “Tube in Tube“ bedea connector under test mated adapter generator receiver RF-tight extension tube connecting cable measuring tube screening cap Tube in Tube measurement of screening attenuation of connectors Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 14


Measuring of EMC Characteristics on Cables for Information & Communication Technics Measuring of cable assemblies bedea tube connector interface assembly under test generator receiver connecting cable screening cap RF-tight extension tube Measuring of the screening attenuation of a cable assemblies Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 15


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Cable with small hole, tube in tube, 0,5 m Well screened CATV-Cable with F-Connector Same cable with one small hole, 3 mm 0 -25 -50 -75 -100 -125 F-Conn. hole in braid -150 0 1 10 100 1000 10000 Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 16


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Test set-up for connecting hardware with tube in tube generator tube device under test receiver tube in tube connecting cable housing test head with screening cap Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 17


Measuring of EMC Characteristics on Cables for Information & Communication Technics Mess-System CoMeT bedea Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 18


Measuring of EMC Characteristics on Cables for Information & Communication Technics Control- and Evaluation Software bedea Delphi C ++ Control of network analyzers Documentation Further tests on communication cables Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 19


Measuring of EMC Characteristics on Cables for Information & Communication Technics bedea Conclusion 1 The Screening effectivenes of Communication cables is described in the lower frequency range by the Transferimpedance Z T and in the upper frequency range by the Screening attenuation a S . At screened balanced cables, the Coupling attenuation a C is the measure of the screening effectiveness as the sum of the Unbalance attenuation of the Pair and the Screening attenuation of the screen. With the test system CoMeT of bedea one can measure the Transferimpedance Z T as well as the Screening attenuation a S in the frequency range from 100 kHz up to and above 3 GHz with one test set-up Furthermore, the Coupling attenuation a C of screened balanced pairs may be measured. Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 20


Measuring of EMC Characteristics on Cables for Information & Communication Technics Conclusion 2 bedea Advantages: simple and easy sample preparation only one test set up for Z T , a S & a C high sensitivity up to and above 125 dB no radiation of electromagnetic energy covers the whole frequencvy range high reproducibility Further information: www.bedea.com Contact person: bmund@bedea.com Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 21


Measuring of EMC Characteristics on Cables for Information & Communication Technics CoMeT Coupling Measuring Tube bedea bmund@bedea.com www.bedea.com Bernhard Mund, bedea Berkenhoff&Drebes GmbH, Herbornerstrasse 100, D-35614 Asslar, Germany, bmund@bedea.com 1- 22

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