Time-Domain Integral-Equation Based Analysis of Complex Structures Loaded With Cables

144 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.This dissertation presents a fast and rigorous hybrid time-domain simulator for analyzing electromagnetic compatibility and interference (EMC/EMI) phenomena on complex structures that involve electrically large platforms (e.g., vehicle shells) along with cable-interconnected antennas, shielding enclosures, and printed circuit boards. To efficiently simulate field interactions with such complex structures, three different solvers are hybridized. (i) A time-domain integral-equation based field solver computes fields on the exterior structure comprising platforms, antennas, enclosures, boards, and cable shields (external fields). (ii) A modified nodal-analysis (MNA)-based circuit solver computes currents and voltages on lumped circuits representing (potentially nonlinear) cable connectors/loads. (iii) A time-domain integral-equation (TDIE)-based transmission-line solver computes transmission-line voltages and currents along cables and at their terminations (guided fields). In its current state, the transmission-line solver is capable of handling transmission lines, which may be described with frequency-dependent per-unit length parameters. Field, circuit, and transmission-line solvers are rigorously interfaced at the cable connectors/loads and along the cable shields. Interfacing of the solvers results in a coupled system of equations that is solved simultaneously at each time step. Computation of the external and guided fields, which constitutes the computational bottleneck of this approach, is accelerated using fast Fourier transform (FFT)-based algorithms. Further acceleration is achieved by parallelizing the computation of external fields. The resulting hybrid solver permits the analysis of electrically large and geometrically intricate structures loaded with cables. The accuracy, efficiency, and versatility of the hybrid simulator are demonstrated by analyzing several realistic EMC/EMI problems, including (i) interference between a log periodic monopole array trailing an aircraft's wing and a monopole antenna mounted on its fuselage, (ii) coupling into coaxial cables connecting shielded printed circuit boards located inside a cockpit, (iii) coupling into coaxial cables from a cell phone antenna located inside a fuselage, (iv) interference between monopole antennas mounted on the mirrors of a car and another monopole antenna located at its rear, and (v) coupling into a multiconductor transmission line located inside the wing cavity of an aircraft.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD