Coupling attenuation up to 2 GHz with virtual Balun

Transcription

1 Coupling attenuation up to GHz with virtual Balun Multiport (four-port) respectively mixed-mode VNA Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, Coupling attenuation up to GHz with virtual Balun screen under test tube with open head ferrite-absorber remaining cable length, appr. 97m load connecting device Generator tube (CoMeT 40) connecting device Generator housing balanced/ unbalanced load DUT screening cap Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany,

2 Overview Physical Basics of creening Transfer impedance, Unbalance attenuation Coupling attenuation Mixed mode -Parameter (virtual Balun) Absorber Coupling attenuation Clamp proccedure, IEC Triaxial procedure, IEC Measurements Discussion Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, 3 Transfer impedance & creening attenuation high frequencies: creening attenuation a = 0 log (P /P ) = 0log 0 (U /U ) [db] Ratio of two powers --> length independent low frequencies: Transferimpedance Wave length λ = (c 0 v k ) / f electrical long: co f > l ε r ε r I I U l < λ/0 U Z T = I Ratio of U/I = R --> length dependent (Ohms law) [mω/m] electrical short: c f < 0 l o ε r (EN ) Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 4

3 umming function nf (l f) cn (l f) cf far n f sin = ( β sin x/x ( β ± β ) ± β ).L.L c c 0, low frequencies near n f 0,0,E+07,E+08,E+09,E+0 introduced from Halme/zentkuti 988, high frequencies n f ( β ± β ) l Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 5 Calculated Coupling Transfer Function T nf a s and Z T vs frequency T s, n f = ( Z ± Z ) F T Z Z l n f db L = m ε T r =,3 f ε r =,0 Z F =0 Tn 0 khz 00 khz MHz 0 MHz fcn fcf GHz 0 GH Transferimpedance creening attenuation & Coupling attenuation n = near end f = far end The Coupling Transfer function T nf results from the multiplication of the equivalent Transfer impedance Z TE and the umming function nf Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 6

4 Triaxial test set-up CoMeT, Principle Transfer impedance & creening (or Coupling) attenuation few khz up to and above 8 () GHz with one test set-up screen under test tube matching resistor screening cap Generator and are included in a modern network analyser IEC Ed Transfer impedance, IEC Ed creening attenuation EN EMC on Communication cables Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 7 Transfer impedance creening attenuation ZT/[mOhm/m as/[db] Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 8

5 creening- or Coupling attenuation with Absorbing clamps creening attenuation or Coupling attenuation from 30 MHz to 000 MHz MD or from 500 MHz to 500 MHz MD absorber test length absorber current transformer screen under test matching resistor IEC resp. EN Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, 9 Coupling attenuation with Balun &Triaxial procedure Coupling attenuation is the interaction of the Unbalance attenuation of the pair and the creening attenuation of the screen DUT tube (CoMeT) balanced/ unbalanced load balun screening cap creened balanced cables, (Cat-cables), multi core cables (and connectors) IEC , Coupling attenuation, triaxial method, Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 0

6 Four Poles or Two ports Network The transmission characteristics of Four Poles or Two ports, such as coaxial cables may be described by the scattering parameter or abbreviated -parameter. a b In matrix notation it is written: port Common two port port b a b b = a a ( ) = a a Figure Common two-port Generator DUT tube (CoMeT 40) symmetric/ asymmetric load Coupling attenuation with Balun = measurement balun screening cap Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, Coupling attenuation with virtual Balun and open head IEC , Coupling attenuation DUT tube with open test head ferrite-absorber remaining length, appr. 97 m connecting device load housing a balanced signal may be obtained with a network analyser having two s with a phase shift of 80. Another alternative are multi-port VNAs (s switched ) Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com,

7 common mode & differential mode Common mode coaxial Gleichtaktbetrieb P c Z com,n U com,n screen/returnpath Z com,f U com,f balanced P d U diff,n screen and/or other Pairs Differential mode U diff,f Z diff,n Gegentaktbetrieb Zdiff,n u ( P P ) a = 0 log / The "Unbalance Attenuation" of a pair describes in logarithmic scale how much power couples from the differential mode to the common mode and vice versa. It is the logarithmic ratio of the input power in the differential mode P d to the power which couples to the common mode P c. d c Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 3 Physical und logical VNA-Ports For the measurement of symmetrical two-ports the physical ports of the multi-port VNA are combined into logical ports Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 4

8 Four port Network For the measurement of symmetrical two-ports the physical ports of the multi-port VNA are combined into logical ports. For a four-port, this results in: a b a b port port 3 Four port port port 4 Four port network - to measure Coupling attenuation with virtual Balun resp. with mxed mode the signal is fed into port and port port 4 is not connected a 3 b 3 a 4 b 4 b b b b std ( ) = a a x a a Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, = DUT a a a a in matrix notation it is written tube with open test head remaining length, appr. 97 m load connecting device housing ferrite-absorber 5 Connecting device for mixed mode Characteristic impedance, primary side Characteristic impedance, secondary side Unbalance attenuation, secondary side (open) Unbalance attenuation, secondary side (matched) Attenuation, primary side (short circuit) Attenuation, secondary side (back to back) x 50 Ohm x 00 Ohm > 40 db > 40 db < 0, db < 0,8 db tube (CoMeT 40) balanced/ unbalanced load connecting device DUT screening cap Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 6

9 Comparison Balun with virtual Balun Generator DUT tube (CoMeT 40) symmetric/ asymmetric load balun screening cap tube (CoMeT 40) symmetric/ asymmetric load connecting device DUT screening cap Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, 7 Balunless vs balun, -FTP cable Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 8

10 Insertion loss of Absorbers to measure Coupling attenuation, Absorber are required to match the system and to avoid back travelling waves into the system insertion loss of Absorbers with Clamp procedure IEC tube absorber inner conductor insertion loss of Absorbers with Triaxial procedure Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, 9 Insertion loss of Absorbers (Triaxial procedure) Best results were achieved with a combination of nanokristaline Absorbers and Ferrite absorbers Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 0

11 Coupling attenuation, tandard or Open test head? screen under test tube with open head ferrite-absorber remaining cable length, appr. 97m load connecting device housing Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, creening attenuation RG 058, tandard & open head Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany,

12 Calculation of unbalance attenuation of balanced pairs longitudinal asymmetry T A R L G / C / C / G / G / C / C / G / L R dx At high frequencies, the asymptotic value approaches to: and at low frequencies the summing function becomes: Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 3 Unbalance at different length Near unbalance of a /TP cable at different length Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 4

13 Return loss Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, 5 Coupling attenuation with Triaxial test procedure Triaxial procedure, open head and standard head, Cat8. cable Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 6

14 Coupling attenuation with absorbing clamp MD Absorbing clamp procedure, MD, 500 MHz to 000 MHZ, Cat8. cable Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, 7 Conclusion With the Triaxial test set-up one can measure Transfer impedance and creening attenuation or Coupling attenuation. To measure Coupling attenuation up to and above GHz, the method of mixed-mode parameters can be used. Length dependence of the Unbalance attenuation is so small, that basically the same results can be expected using the open test head with a test length of 00m and the standard test head of the triaxial tube with a length of 3m However, the impact of the Return loss shall be considered, when measuring short lengths. The measurements presented show, that taking into account the boundary conditions, similar results can be expected from the triaxial method with open test head and with the standard head, as well as from the clamp method. Further info: Further questions: bmund@.com Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 8

15 Progress of International tandards for Triaxial Procedure, TR Ed Introduction to electromagnetic (EMC) screening measurements /438/CD Ed urface transfer impedance - Triaxial method 03-0 published Ed hielded screening attenuation, test method for measuring of the screening attenuation a up to and above 3 GHz 46/439/CDV Ed hielded screening attenuation test method for measuring the Transfer impedance Z T and the screening attenuation a or the /49/CDV coupling attenuation a C of RF-Connectors and assemblies up to and above 3 GHz, Tube in tube method Ed Electromagnetic Compatibility (EMC) Coupling attenuation, triaxial method Ed hielded screening attenuation test method for measuring the creening Effectiveness of Feedtroughs and Electromagnetic Gaskets Test method for measuring transfer impedance and screening attenuation - or coupling attenuation with Triaxial Cell Relationship between surface transfer impedance and screening attenuation, Conversion a and Z T in preparation /494/CD 46/50/CDV /5/DTR Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 9 Literature [] 46C/00/CD - IEC 656-9: Multicore and symmetrical pair/quad cables for digital communications - Part 9: Cables for horizontal floor wiring with transmission characteristics up to GHz - ectional specification [] 46C/00/CD - IEC 656-0: Multicore and symmetrical pair/quad cables for digital communications - Part 0: Cables for work area wiring with transmission characteristics up to GHz - ectional specification [3] IO/IEC TR Ed..0: INFORMATION TECHNOLOGY - Guidance for balanced cabling in support of at least 40 Gbit/s data transmission [4] IEC , Metallic communication cable test methods - Part 4-9: Electromagnetic compatibility (EMC) - Coupling attenuation of screened balanced cables, triaxial method [5] IEC , Metallic communication cables test methods - Part 4-5: Electromagnetic compatibility (EMC) - Coupling or screening attenuation - Absorbing clamp method [6] IEC , Metallic communication cable test methods - Part 4-3: Electromagnetic compatibility (EMC) - urface transfer impedance - Triaxial method [7] Thomas Hähner, Bernhard Mund EMV-Verhalten symmetrischer Kabel EMC Journal 4/997 [8] Yangawa, K.; Cross, J. Modal decomposition (non-balun) measurement technique: error analysis and application to UTP/TP characterisation to 500 MHz; Proceedings of the IWC 995; pp [9] Christian Pfeiler u.a., Analysis of Balance Parameters of Cables for High Data Rate Digital Communications, Proceedings of the 6nd IWC Conference, Charlotte, U, Nov. 03 [0] Thomas Hähner & Bernhard Mund, Balunless Measurement of Coupling Attenuation of Balanced Cables & Components, Wire and Cable Technology International, July 03 [] Thomas Hähner, Messung der Übertragungseigenschaften symmetrischer Kabel bis in den GHz Frequenzbereich, Technische Akademie Esslingen [TAE], 5. Oktober 03 [] Thomas Hähner, Bernhard Mund Test methods for screening and balance of communications cables; Proceedings of EMC Zurich, 999, pp [3] Lauri Halme, Bernhard Mund: Messen der chirmwirkung elektrischer Kabel, Anwenderforum Elektrische Kabel, Technische Akademie Esslingen [TAE], 5. Oktober 03 Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 30

16 Control- and Evaluation - oftware WinCoMeT - Control of the VNA - evaluation of test results - documentation - Data export to M-Excel -printing - full version with transmission Parameters of Communication cabes including - FFT and gating - ready for mixed mode measurements Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 3 Thank you for your attention??? bmund@.com Bernhard Mund, Berkenhoff&Drebes GmbH, Herborner trasse 00, 3564 Asslar, Germany, bmund@.com, 3