A hybrid method combining the finite-element time-domain (fetd) method and transmission line (TL) equations (fetd-TL) is presented for evaluating the transient responses of a lossy TL in an apertured rectangular enclo...
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A hybrid method combining the finite-element time-domain (fetd) method and transmission line (TL) equations (fetd-TL) is presented for evaluating the transient responses of a lossy TL in an apertured rectangular enclosure excited by electromagnetic pulses. First, the electric fields in the enclosure without the TL are calculated based on the Bethe's small holes theory and the mirror procedure. Then, the enclosure's electric fields are introduced into the second-order TL equation for current as the equivalent distributed sources. The transient currents induced on the TL are obtained by solving the second-order TL equation for current based on the fetd method with a single iteration variable. Finally, the transient voltages induced on the TL are computed by discretising the first-order TL equation. Compared with the method based on finite-difference time-domain (FDTD) method and TL (FDTD-TL) via several examples, the proposed hybrid method is proved to be correct and effective, which possesses much higher convenience and efficiency than FDTD-TL method in dealing with TL model terminated by complex lumped parametric networks.
An efficient field-to-line coupling model in the time domain is developed combining the second-order decoupled multiconductor transmission lines (MTLs) equations and the finite-element time-domain (fetd) method for ev...
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An efficient field-to-line coupling model in the time domain is developed combining the second-order decoupled multiconductor transmission lines (MTLs) equations and the finite-element time-domain (fetd) method for evaluating the electromagnetic (EM) transient response of MTLs over a lossy ground excited by a high-altitude EM pulse (HEMP). First, the incident HEMP electric fields on the lines are calculated as equivalent distributed sources introduced into the MTLs equations. Then, the discrete fetd equations for the lines against the HEMP, in which the effect of frequency-dependent parameters caused by the ground impedance is considered, are derived using the fetd method with current as the single iteration variable. Finally, the transient currents induced on the lines are obtained by assembling all the discrete fetd equations into the global fetd equation, and the transient induced voltages on the lines are calculated by discretising the coupled equations with respect to current and voltage. The proposed model is successfully compared with the finite-difference time-domain method via several examples. It is then employed to analyse the effect of various parameters on the transient currents including the polarisation and the incident angles of the HEMP, the conductivity, and the relative permittivity of the soil.
We put forward a novel hybrid algorithm, based on merging finite-element time-domain (fetd) with finite-difference time-domain (FDTD) methods, to solve electromagnetic problems involving fine structures. The fetd meth...
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We put forward a novel hybrid algorithm, based on merging finite-element time-domain (fetd) with finite-difference time-domain (FDTD) methods, to solve electromagnetic problems involving fine structures. The fetd method with unstable modes removing (UMR-fetd) is employed in regions relating to fine structures, while the FDTD method is adopted in the other regions. The suggested hybrid approach reduces the dimension of the system matrix for the UMR-fetd method, thus decreasing the consumption of computing resources. Besides, the hybrid algorithm makes it possible to adopt a uniform and large time step in the whole computational domain, thus improving computational efficiency. Numerical results confirm the good performance of the proposed hybrid algorithm to solve electromagnetic problems involving fine structures.
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