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Shielding effectiveness of metallic enclosures with curved metallic objects on vehicle platform illuminated by an incident EMP is studied using hybrid FDTD method combined with a modified conformal technique. Some important factors including polarization direction of the incident wave, the incident angle of the exterior EMP, and different incident waveforms are investigated in detail for their effects...
Research on time-domain responses characteristics of the broadband planar antenna illuminated by an in intentional electromagnetic pulses (EMP) is carried out in this paper. An efficient hybrid time-domain simulation method based on FDTD method combined with the c conformal technique is implanted for studying an EMP coupling with some typical broadband planar antennas widely used in the wireless communication...
Unintentional as well as intentional electromagnetic interference can cause improper functionality of microwave circuits or systems. In this paper, our attention is focused on transient response characterization of microwave MESFET amplifiers, which are used widely in the integration of communication circuits and systems, under the impact of an intentional electromagnetic interference(IEMI) source...
This paper presents a parameter optimized local one dimension (PO-LOD) FDTD method based on (2, 4) stencil to achieve better dispersion performance. With different optimization schemes, the method can be applied to satisfy various requirements, such as minimum dispersion error in the axes direction, in the diagonal direction, for two arbitrary angles, and minimum average dispersion error. Through...
A hybrid time-domain method is proposed for characterizing electromagnetic interference (EMI) signals in some composite structures with two-wire ribbon cable transmission lines, metallic enclosures, and even lumped active devices involved. In order to fast capture the inner EMI signals induced, Finite Difference Time-Domain (FDTD), and multi-conductor transmission lines (MTL) methods are combined...
A novel approach for modeling photonic crystal circuits is proposed. In this approach, the effective length of photonic crystal waveguide between two devices is estimated. The frequency response of the photonic crystal circuit is modeled as a Fabry-Perot cavity. An example of double 90-degree bend is analyzed by the approach. The results have great agreement with those obtained by finite-difference...
This paper presents a finite difference method for the design of gradient coil in MRI. In this method, a linear matrix equation is formulated using a finite-difference approximation of the current density in the source domain and an optimization procedure is then carried out to solve the resulting inverse problem and the coil winding pattern are found. The developed algorithm is tested with a transverse...
This paper presents a three dimensional finite-difference time-domain (FDTD) scheme in cylindrical coordinates with an improved algorithm for accommodating the numerical singularity associated with the polar axis. The regularization of this singularity problem is entirely based on Ampere's law. The proposed algorithm has been detailed and verified against a problem with a known solution obtained from...
The voltage and current responses induced on a multi-conductor transmission lines (MTL) network with some nonlinear devices are studied in this paper, which is placed in a cabin with thin slots on its wall. The mathematical treatment is based on the finite-difference time-domain (FDTD) method combined with telegraph equations and modified nodal analysis (MNA) method. The accuracy of our developed...
The sub-cellular thin wire FDTD algorithm is modified and combined into a single FDTD method so that it is able to capture the SE performance of the enclosure with a number of geometrical and physical parameters changed, illuminated by an electromagnetic pulse. Then several methods to mitigate the coupling were introduced and investigated in detail.
This paper presents an unconditionally stable three-dimensional (3-D) finite-difference time-method (FDTD) based on the locally one-dimension (LOD-FDTD) scheme. The unconditional stability is proven theoretically and validated numerically. Numerical dispersion of the method is also derived analytically. Through the dispersion analysis and a numerical example, the proposed LOD-FDTD method is found...
This paper presents an improved sub-cell model for modeling thin material in metallic enclosures using the finite-difference time-domain (FDTD) method. The enhanced thin material sub-cell algorithm proposed can model thin magnetic material sheets including their losses. Our FDTD results are compared with the shielding effectiveness obtained by transmission line method, with good agreements achieved...
A modified conformal technique for fourth-order finite-difference time-domain (FDTD (2, 4)) is proposed. This conformal scheme has higher-order accuracy than that of conventional FDTD and FDTD (2, 4) methods, which are caused by staircasing errors when modeling curved metallic objects. Two integration loops of Faradaypsilas law for the updating of magnetic field components are introduced here. Numerical...
Shielding effectiveness of metallic enclosures with thin slots, illuminated by an obliquely incident EMP, is studied using hybrid FDTD method combined with thin-slots formulas (TSF). The developed code is verified by comparing our numerical result with the measurement, and an excellent agreement is achieved. Parametric studies are performed to show geometrical and physical parameters of the metallic...
A modified algorithm of perfectly matched layer (PML) is proposed in finite difference time domain (FDTD) for handling dispersive media and composite objects. This algorithm obtains the iterative equations from frequency domain by Z-transform, by which we can also treat dispersive media in Maxwell's equations. Some numerical examples are given to validate the method.
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