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Cost 286 Workshop on „ EMC Aspects of Wireless Communications in Transport Systems”

Cost 286 Workshop on „ EMC Aspects of Wireless Communications in Transport Systems”. Analysis of Leaky Section Cables for Multi-Band Aircraft Cabin Communications with different Measurement Techniques Sven Fisahn 1 , Michael Camp 1 , Núria Riera Díaz 2 , Robert Kebel 3 , Heyno Garbe 1

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Cost 286 Workshop on „ EMC Aspects of Wireless Communications in Transport Systems”

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  1. Cost 286 Workshop on„EMC Aspects of Wireless Communications in Transport Systems” Analysis of Leaky Section Cables for Multi-Band Aircraft Cabin Communications with different Measurement Techniques Sven Fisahn1, Michael Camp1, Núria Riera Díaz2, Robert Kebel3, Heyno Garbe1 1Institut für Grundlagen der Elektrotechnik und Messtechnik, Universität Hannover 2 Institut für Kommunikation und Navigation, Deutsches Zentrum für Luft- und Raumfahrt 3 Lightning Protection and Electromagnetic Compatibility, Airbus Deutschland GmbH e-mail: fisahn@ieee.org

  2. Analysis of LSC by Measurement • Leaky Section Cable (LSC) • Measurement Setup • Open Area Test Site (OATS) • GTEM Cell Measurement • Near Field Scanning • Attenuation Measurement • Measurement Results • Transient Signal (Near Field Scanning, Attenuation) • CW-Signal (OATS, GTEM Cell, Attenuation) • Summary

  3. leaky section non-leaky section Leaky Section Cable (LSC) • Enable use of portable electronic devices (PEDs) inside cabin (e.g. laptops, mobile phones) • Antennas for multi-band aircraft cabin communications (e.g. WLAN, GSM, UMTS, DECT X2X) required • LSC functions both as a transmission line and as an antenna • System integration process requires detailed information about radiation and transmission behaviour and interference potential

  4. Measurement Setup (Open Area Test Site) DLR test site in Oberpfaffenhofen (Germany) • Circular far field radiation pattern • Vertical and horizontal polarization • CW-signals (700 MHz to 2.5 GHz)

  5. Measurement Setup (GTEM Cell Measurement) GTEM 1250 at GEM, University of Hannover • Circular near field radition pattern • CW-signals (450 MHz to 6 GHz) • cable length 1 m, includes 1 leaky section

  6. Measurement Setup (Near Field Scanning) Near field measurements at GEM, University of Hannover • Distribution of electric field strength along the cable  CW-signals (450 MHz to 6 GHz) • Radiation at front side and back side of LSC  Transient signals (rise time: 5 ns) • Conical and biconical field probes

  7. Measurement Setup (Attenuation) Attenuation measurement at GEM, University of Hannover • Transmission behaviour • CW-signals (450 MHz to 6 GHz) • Measurement setup • Cable is unrolled and positioned on the concrete floor of the laboratory • Scattering parameter S21(transfer function of the cable and the connectors at each end)

  8. U / V U / V Test pulse at input of leaky cable Test pulse at output of leaky cable t / s t / s Measurement Results (Transient Signal) Transmission measurement • Fast transient pulses (rise time 5 ns) with double exponential character (cable length 10 m) • Pulse shape nearly identical, merely amplitude damped

  9. |U(j)| / (V/m/Hz) Spectral energy distribution Input(---- blue) Output(---- red) f / Hz Measurement Results (Transient Signal) Comparison of the spectral energy distribution • Identical characteristics of both spectra • Pulse shape nearly unaffected by transmission throughleaky section cable

  10. E(t) / (V/m) Electrical field at leaky side t / s E(t) / (V/m) Electrical field at back side t / s Measurement Results (Transient Signal) Radiation measurement with conical field probe • Electric field strength much higher on leaky side

  11. |E(j)| / (V/m/Hz) |E(j)| / (V/m/Hz) Electrical field at leaky side Electrical field at backside f / Hz f / Hz Measurement Results (Transient Signal) Spectra of radiated electric field • Spectral energy distribution < 1 GHz reduced • Spectral energy distribution > 1 GHz very similar • Discrete frequencies (75 MHz, 150 MHz, 225 MHz,...)

  12. Measurement Results (CW-Signal, OATS) Circular radiation pattern via OATS • Four distances d from the cableaxis at 2 GHz • Single and wide main lope for parallel polarization • Zeros at 0 and 180 deg. for perpendicular polarization

  13. Measurement Results (CW-Signal, GTEM Cell) Circular radiation pattern via GTEM Cell measurement • Main lope in lower frequency range < 2 GHz • Radiation zeros occur in upper frequency range

  14. Measurement Results (CW-Signal, GTEM Cell) Circular radiation pattern via GTEM Cell measurement • Linear and normalized scale shows good agreement with OATS measurements in frequency range < 2 GHz

  15. Measurement Results (CW-Signal, NF-Scan) Field distribution along the cable • Field strength along the cable decreases exponentially • High near field values in leaky sections • High attenuation in upper frequency range

  16. Measurement Results (CW-Signal, Attenuation) Attenuation measurement of cable with 35.7 m length • Attenuation of LSC • increases towards higher frequencies • about 12 dB in frequency range < 1 GHz • larger than 50 dB in freq. range > 3.5 GHz

  17. Summary • Motivation for investigations of LSC • Principle build up of leaky section cable (LSC) • Measurement techniques • Open area test site (OATS) • GTEM cell measurement • Near field scanning • Attenuation measurement • Measurement results • Transient signal • CW-signal

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