Hybrid Finite-difference Time-domain Method Research Articles

An efficient hybrid method for analyzing the coupling response of microstrip antenna system

This paper presents an efficient hybrid method consisting of Lorentz reciprocity theorem, finite-difference-time-domain (FDTD) method, thin wire model, transmission line (TL) equations and transfer impedance model, which can be utilized to analyze the system-level transient responses of the microstrip antenna system with antenna, metallic enclosures, braided shielded cable, and lumped element, when illuminated by an external electromagnetic pulse (EMP). In order to avoid over-fine mesh generation and repeated modeling of the antenna in multiple simulations, Lorentz reciprocity theorem is employed to extract an equivalent source model of antenna coupling, thereby improving the computational efficiency. Then, the transfer impedance model and thin wire model are incorporated into the FDTD-TL method efficiently to deal with the back-door coupling through the shielding layer of feeding coaxial cable. Finally, the hybrid FDTD method combined with the extracted equivalent source of antenna coupling is utilized to solve the coupling responses of the whole antenna system. The results of numerical simulation are verified by comparing with the simulation results of CST CS. Then, considering the influence of different incident conditions of external EMP, the characteristics of the coupling response of the system are analyzed. The obtained coupling response information demonstrate that the proposed method is available for further designing electromagnetic protection of the inner circuits of the microstrip antenna system against the impact of external EMP.

EMI effect simulation of braided cable network using a hybrid FDTD method

AbstractThis paper proposes a novel time domain numerical scheme based on a modified finite‐difference time‐domain (FDTD) method for electromagnetic interference (EMI) analysis of braided cable networks. In this method, a reasonable physical boundary condition is constructed by a transfer impedance model, while the spatial fields can be applied by way of adding incentive items into the transmission line equations. Besides, the full‐wave finite‐difference time‐domain(2, 4) method with thin wire model, transmission line equation and the modified nodal analysis are combined in order to solve cable‐interconnect line network transient responses in the problem of field‐line‐circuit union simulation. This method has good agreements with HSPICE. In addition, the method is used successfully in analyzing a cable‐interconnect network with different shielding characteristics.

Hybrid FDTD Method for Studying Electromagnetic Coupling Effects of Transmission Line Networks

This letter proposes a novel hybrid finite-difference time domain (FDTD) method, which combines the full-wave FDTD (2, 4) method with a thin-wire model, a transmission-line equation, the Kirchhoff's law, and a two-port equivalent-circuit FDTD model, where antenna–cable coupling model and modified nodal analysis method are also implemented through a set of proper boundary conditions. In our method, both coaxial cable and thin-wire antenna are treated together without geometric meshing for full-wave simulation, and all the coupling processes among fields, transmission line equations, and circuit loads are carried out at the same time step. Such hybrid method is verified by comparing with both PSPICE and traditional FDTD method, and good agreements are obtained. Further, the proposed method is successfully applied to predict the transient electromagnetic responses of some complex transmission line networks in a vehicle-based metallic shelter.

Improved Hybrid FDTD Method for Studying Tunable Graphene Frequency-Selective Surfaces (GFSS) for THz-Wave Applications

One hybrid finite-difference time-domain (FDTD) method is proposed for studying transmission characteristics of a THz wave through some tunable dispersive graphene frequency-selective surfaces (GFSSs) biased by an electrostatic or a magnetostatic field, respectively. It integrates auxiliary differential equation (ADE)-FDTD with high-order conformal FDTD (2, 4) so as to handle atomically thin periodic structures on an electrically anisotropic substrate with high flexibility and accuracy. The dispersion error and computational efficiency of the developed algorithm is validated in comparison with the piecewise linear recursive convolution (PLRC)-FDTD and commercial software HFSS, respectively. Numerical studies are further performed to demonstrate its capability for characterizing the effects of chemical potential of graphene, biasing electrostatic and magnetostatic fields, and geometrical parameters of different GFSSs on the central frequencies and 3-dB bandwidths of their passbands and stopbands. In particular, both frequency selectivity and tunability of GFSSs made of single- and double-layer periodic split-ring resonators are predicted, which can be exploited for developing some novel tunable THz structures.

Wideband Modeling of Graphene-Based Structures at Different Temperatures Using Hybrid FDTD Method

An efficient finite-difference time-domain (FDTD) algorithm is proposed for studying frequency- and temperature-dependent characteristics of some graphene-based structures, with auxiliary differential equation-FDTD method and its conformal modification technique integrated together for handling such atomically thin and electrically dispersive periodic geometries. Numerical results are presented to show their tunable transmittances, surface plasmon polarization-mode characteristics and Fano resonances, where the effects of chemical potential of graphene, biasing electric field strength, as well as operating temperature are captured and investigated in detail.

Hybrid Technique Combining the FDTD Method and Its Convolution Formulation Based on the Discrete Green's Function

In this letter, a technique combining the finite-difference time-domain (FDTD) method and its formulation based on the discrete Green's function (DGF) is presented. The hybrid method is applicable to inhomogeneous dielectric structures that are mutually coupled with wire antennas. The method employs the surface equivalence theorem in the discrete domain to separate the problem into a dielectric domain simulated using the FDTD method and a wire antenna simulated using the DGF formulation of the FDTD method. Therefore, both methods can be perfectly coupled without introducing any additional errors to the FDTD solution. Applications of the hybrid FDTD method are illustrated by two canonical problems involving half-wavelength dipole antennas and a dielectric object. If the DGF length is equal to the number of iterations in a simulation, the presented hybrid technique returns the same results as the direct FDTD method (assuming infinite numerical precision of computations).