Conformity Magazine - August 2008 - (Page 38)

3. Transfer of knowledge and application of recent efforts within electrical interconnects and packaging modeling to the automotive industry. Figure 9 illustrates the cable harness inside a realistic vehicle. Multiple bends are observed; therefore, in order to accurately characterize the cable harness, it is partitioned into multiple sections, as illustrated in Figure 10. The numerical simulations have been performed by means of a proprietary software tool [7] specialized for harness cable analysis and based on the already mentioned 2D TL method. Familiar to most electric engineers is the circuit simulation of electronic and electric functionality at component level by using SPICE-like solvers (equivalent circuits). The TL method can be considered as a link between circuit simulations (electric functionality) and field simulations (electromagnetic effects). Figure 11 represents the SPICE equivalent circuit of the cable harness illustrated in Figures 9-10. Figure 9: View of the vehicle with in evidence the cable harness The advantage of this approach is obvious, due to the flexibility of using the SPICE circuit in time and/or frequency domain, as well as the possibility to use any kind of source (different waveforms) and/or possible connections among pins. For instance, Figure 12 illustrates the near end crosstalk (NEXT) and the far end crosstalk (FEXT) in time domain, while Figure 13 represents the frequency domain response in terms of scattering parameters (frequency range is 100MHz-2 GHz) Important considerations can be addressed, as follows: 1) the crosstalk effect on neighboring lines depends on the distance of the different lines of the cable harness; 2) an induced current is observed on the other lines when a rising edge occurs on the input signal; and 3) oscillations are revealed in the current waveform, probably due to impedance mismatches at the terminations. The EMI radiation of the cable harness is also provided in order to detect hot spots of the field in specific locations for defined frequency values. In particular, the emission calculation is done in frequency domain and, whenever the simulation is done in time domain, all currents for each single signal lines are automatically transformed via FFT (fast Fourier transformation). An integral equation makes possible efficient and fast calculations of the radiated field at any wanted position in three-dimensional space, regardless how big the distance is between source and observation points. Figure 14 illustrates the magnitude of the electric field on a specific plane (which mimics a specific position within the vehicle) for different frequencies. It is possible to see that, when increasing the frequency value, the radiation gets stronger and the hot spots are differently localized. Figure 10: Detail of the cable partitioned into small TL sub-sections Figure 11: SPICE equivalent circuit 38 Conformity AUGUSt 2008

Table of Contents Feed for the Digital Edition of Conformity Magazine - August 2008

Conformity Magazine - August 2008 Contents Editor’s Note FCC Seeks Comment on Reauction of 700 MHz D Block Commission Cracks Down (Again!) on Junk Fax Marketer Canada Levies Fees for Public Safety Radio Spectrum FDA Issues Guidance on Medical Device Tracking Greenpeace Challenges Video Game Manufacturers The IEEE EMC Society: A Proud History of Accomplishments ESD Open Forum An Update on Changes to the Automotive ESD Standard, ISO 10605 Modeling of Radiated Electromagnetic Disturbances in Automotive Applications Design Issues in Automotive Radio Frequency Systems IEEE EMC Symposium IEEE 2008 Show Preview Exhibitors Buyer’s Guide Product News Most Eco-Friendly Companies Updated Standards List For the EU’s Pressure Equipment Directive Commission Issues Updated Standards List For Directive on Gas-Fired Appliances HHS Releases Fact Sheet on U.S. Imports from China Customs Agents Seize Holiday Lights IEEE PSES Symposium Set for October CPSC Actions in the News IEC Standards Update UL Standards Update Telcordia Standards Update From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Product Reviews Advertisers

Conformity Magazine - August 2008

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