Studies On Fast Algorithms Of Time Domain Integral Equation And Their Applications

Marching-on-in-Time (MOT) based on time-domain integral-equation (TDIE) solver has the potential to analyze large-scale electromagnetic compatibility (EMC), electromag-netic pulse (EMP), broadband antenna or radar cross section (RCS) problem, while the nu-merical unstability and low computational efficiency prevent classical MOT from being widely used. The purpose of this thesis is to develop efficient, fast TDIE solver, and to study its applications.Derivations of time domain EFIE, MFIE and CFIE in the transient analysis of elec-tromagnetic wave scattering from three-dimensional perfect electrically conducting (PEC) bodies are reviewed firstly in this thesis. Then the causes of MOT instability are systemati-cally studied, which consummates the stability theory of MOT algorithm. The result of analysis indicates that the remedies for a stable MOT are reducing the discretization error and restraining the accumulation of the numerical error in the numerical results; hence a stable MOT solver is obtained based on high order singularity extraction technique for RTBI and digital low pass filter technique. For any practical problem, the MOT algorithm proposed here is stable. An improved spatial basis function for straight thin wire is pre-sented; hence the current on the wire antenna can be modeled better.Two accelerated MOT algorithms, named approximate principle enhanced MOT algo-rithm and plane-wave time-domain enhanced MOT (PWTD-MOT) algorithm respectively, are presented to reduce the computational complexity of classical MOT. The former one employs the nature characteristic of the current distribution on the body illuminated by a short pulse to reduce the computational complexity of retarded-time boundary integrals (RTBIs), i.e., RTBI can be evaluated approximately by only calculating on the neighbor regions and the"active regions". The"active regions"mean the regions just being illumi-nated by the incident pulse at a historical moment. The latter one uses the plane-wave de-composition technique to evaluate the RTBIs efficiently. Both of the accelerated MOT al-gorithms can reduce the computational complexity of evaluating RTBIs considerable, while the first one is more suitable for wideband RCS prediction of simple large-scale scatter, and the second one is almost suitable for all kinds of problems.Several transient and wideband electromagnetic problems are analyzed using PWTD- MOT algorithm, including evaluation of the performance of compact range field reflector at low frequency band, EMC/EMI analysises and a simulation of wireless channel.The ad-vandages of PWTD-MOT have been demonstrated in these practical examples.