RF Ingress MEasurements for STP Cables from from Automotive ALSE Test ... Direct measurement of RF ingress voltage at cable ... RF Ingress MEasurements for STP Cables from Automotive ALSE

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<ul><li><p>RF Ingress Measurements for STP Cables from Automotive ALSE Test</p><p>Larry CohenRamin Shirani</p><p>11/8/2017</p></li><li><p>11/8/2017</p><p>Overview Measurement of the differential RF ingress voltage induced at the termination of an </p><p>automotive shielded cable (STP) based on standard automotive radiated immunity absorber-lined shielded enclosure (ALSE) test method described in ISO 11452-2 </p><p> Test results from 80 MHz to 1 GHz and 1GHz to 3GHz </p><p> Direct measurement of RF ingress voltage at cable terminations; no PHY MDI port interface</p><p> Results are for differential rms voltage vs frequency at cable termination (100 Ohms differential impedance)</p><p> Test performed on STP with H-MTD connectors and STP with HSD connectors; both cable assemblies were 2 meters long with only end connectors</p><p>2</p></li><li><p>11/8/2017</p><p>3 ALSE Automotive Cable RF Ingress Measurement Test Setup</p><p>Ground plane table(90 cm above ground</p><p>plane floor)</p><p>1 m</p><p>1.5 m</p><p>DUT cable harness, totallength &lt; 2 meters</p><p>Balun</p><p>Antenna height is 1mabove ground plane floor</p><p>Absorber-linedshielded chamber</p><p>(ALSE)</p><p>Insulating cable support(5 cm thick)</p><p>GPIBControl PC</p><p>Shielded TerminationBlock</p><p>(Sits on 5 cm ofinsulating material)</p><p>0.1 m</p><p>Shielded enclosurefor cable adapter</p><p>(Sits on 5 cm ofinsulating material)</p><p>CableAdapter</p><p>&gt;1.5 m</p><p>Cableconnector</p><p>GPIB</p><p>RF Power Amplifier</p><p>RF SignalGenerator50 50 </p><p>GPIB GPIB</p><p>50 </p><p>Ferriteclamp</p><p>INOUT</p><p>50</p><p>DirectionalCoupler (40 dB)</p><p>FWDCPL</p><p> SpectrumAnalyzer / RFPower Meter</p><p>50 </p><p>EMC Lab GPIBControl PC for</p><p>ALSE TestGPI</p><p>B</p><p>The spectrum analyzer and directional coupler are used to monitorthe forward signal power to the antenna. At each frequency, thesignal generator output is adjusted to match the forward signalpower previously obtained during the calibration procedure.</p><p>R&amp;S FSU-8SpectrumAnalyzer</p><p>(8 GHz BW)</p><p>GPIB</p><p>Balun</p><p>GPIB</p><p>Ferriteclamp</p><p>50</p><p>Aquantia testequipment</p><p>EMC lab testequipment</p><p>24 ft. coaxialcable</p><p>ETSPI-102</p><p>Added 3 dBattenuators toimprove differentialport return loss</p><p>-3dB</p><p>-3dB</p><p>0.2 m</p><p>0.2 m 61 61</p><p>Split-ring</p><p>ferriteclamps(on 6"coax)</p><p>Split-ringferrite</p><p>clamps</p><p>Horn antenna aligned 10 cmoffset from DUT for testingfrom 1 GHz to 3 GHz</p><p>Test field strength is 50 V/mfrom 80 MHz to 3 GHz (CW).</p><p>Measured result scaled to100 V/m by adding 6 dB.</p><p>Bilog antenna aligned tomidpoint of cable span fortesting from 80 MHz to 1 GHz</p><p>Balun</p><p>The spectrum analyzerdetermines both the frequencyand power of the RF ingresssignal by monitoring themaximum peak signal (RFingress from the radiation) duringeach frequency sweep.</p><p>31 31</p><p>61 31</p><p>Cable adapter breaks out STP andSSQ 100 differential cablechannels to a pair of 50 SMA jacks</p><p>Split-ring ferrite clamps added to allcoaxial cables inside chamber tosuppress stray test fixture RFingress below 1 GHz and lower themeasurement noise floor.</p><p>Shielded enclosure has added coppertape on seams and EMI gaskets to</p><p>reduce stray ingress above 500 MHz</p><p>&gt;2 m</p><p>3</p></li><li><p>11/8/2017</p><p>4 ALSE Automotive Cable RF Ingress Measurement Test Setup (80 MHz to 1 GHz)</p><p>Antenna</p><p>Shielded Cable (DUT)</p><p>Shielded Cable Adapter</p><p>24 ft Coaxial Cable</p><p>Copper Ground Plane Table</p><p>ETS PI-102</p><p>Shielded Termination Block</p><p>Split-ring Ferrite Clamps</p><p>4</p></li><li><p>11/8/2017</p><p>5 Test Setup Measurement noise floor is the measured stray RF ingress from the stand-alone test fixture</p><p> Measured under ALSE test conditions with the cable DUT disconnected from the cable adapter and all unconnected cable ports on the test fixture covered with copper tape</p><p> Cable adapter enclosures have EMI gasket seals between the cable connectors and enclosure and copper tape on seams to reduce stray ingress above 500 MHz</p><p> Added split-ring ferrite clamps to the exposed coaxial cables inside the chamber to reduce stray ingress coupling below 500 MHz; moderately effective below 200 MHz</p><p> Spectrum analyzer operated in free running sweep mode; measures both frequency and level of maximum peak signal during each frequency sweep</p><p> Proper measurement requires a spectrum analyzer measurement noise floor &lt; -150 dBm/Hz to observe weak ingress signals, otherwise an additional pre-amplifier is necessary</p><p> RF disturber field calibrated to 50 V/meter using a CW signal (no 80% AM) </p><p> Reduced field strength to minimize harmonic distortion from the EMC lab RF amplifier</p><p> Harmonic distortion can introduce measurement errors for this test setup by causing the spectrum analyzer to observe the wrong (harmonic) peak</p><p> Test level a compromise between harmonic distortion and improved signal observability</p><p> Used linear spaced frequency sweep step size(s) from ISO 11452-1 Table 2; dwell time set at 2 sec.5</p></li><li><p>11/8/2017</p><p>6</p><p>Port 2(Cable Adapter)100 Differential</p><p>Port 1(Spectrum Analyzer)50 Single-ended</p><p>ETSPI-102(Balun)</p><p>-3dB</p><p>-3dB</p><p>24 ft. Coaxial cable6 in Coaxial cables</p><p>ALSE Test Fixture</p><p>6</p></li><li><p>11/8/2017</p><p>7</p><p>7</p></li><li><p>11/8/2017</p><p>8</p><p>8</p></li><li><p>11/8/2017</p><p>9</p><p>9</p></li><li><p>11/8/2017</p><p>10</p><p>10</p></li><li><p>11/8/2017</p><p>11</p><p>Observations and Next Steps Overall, the RF ingress in the STP cable with the H-MTD connectors was lower than the STP cable with the </p><p>HSD connectors </p><p> The peak RF ingress in the STP cable with the H-MTD connectors (~1.5 mV rms) was lower than STPcable with the HSD connectors (~5 mV rms) over 80MHz to 1GHz </p><p> The peak RF ingress in the STP cable with the H-MTD connectors (~3 mV rms) was lower than the level in the STP cable with the HSD connectors (~6 mV rms) over 1 GHz to 3 GHz</p><p> There is a measurement discontinuity at 1 GHz because of the change in relative antenna position with the (slightly) different test setups for measurements above and below 1 GHz</p><p> RF ingress measurements below 200 MHz may not be accurate because of a higher measurement noise floor from stray RF ingress into the test fixture cabling</p><p> Some reduction in the measurement noise floor below 200 MHz obtained by adding split-ring ferrite clamps to the exposed coaxial cables inside the chamber</p><p> Passing the 24 ft coaxial cable outside the chamber through a bulkhead connector at the chamber wall instead of a shielded aperture should provide some additional improvement</p><p> Next steps Extend measurements to 5 GHz; insertion loss notches reported in this range (possibly caused by helical </p><p>shield construction) may have important implications for radiated immunity</p><p> Test on different cable types (e.g. SSQ) and cable spans with connector junctions</p><p> Test on cable bundles 11</p><p>RF Ingress Measurements for STP Cables from Automotive ALSE TestOverviewALSE Automotive Cable RF Ingress Measurement Test SetupALSE Automotive Cable RF Ingress Measurement Test Setup (80 MHz to 1 GHz)Test Setup Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Observations and Next Steps</p></li></ul>

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