An anisotropic perfectly matched layer-absorbing medium for the truncation of FDTD lattices

Abstract

Finally, we investigate a scattering problem for a square conducting scatterer with a layer of dielectric coating, whose geometry is depicted in Figure 4(a), where K 1 ϭ 2, S 1 ϭ 0.4775 m, S 2 ϭ 0.3183 m, and the thickness of the dielectric coating layer is 0.0796 m. The detailed discretization information for the uniform PSTD and the TSNU-PSTD can be seen in Table 2. The results for the structure, with and without dielectric coating by the conventional PSTD and the TSNU-PSTD approaches, are plotted in Figure 4(b) and they are in excellent agreement compared to those obtained from the moment of methods (MoM) [11]. This time, the TSNU-PSTD uses 35.6% of the computational space of the uniform PSTD. CONCLUSIONIn this paper, we have successfully applied the TSNU-PSTD algorithm, based on a grid transformation, for the 2D scattering analysis. It is found that this algorithm has the same computational complexity at the order of N log N as the conventional PSTD algorithm. In comparison to the conventional PSTD method, this TSNU-PSTD algorithm is much more flexible and has great potential for use in generalized electromagnetic applications, especially for incommensurate systems with fine structures. INTRODUCTIONSuspended plate antennas (SPAs) with the thick dielectric substrates of very low dielectric constants have been widely proposed for broadband applications. Usually, the material supporting the radiating plate is an inexpensive foam layer or air. The spacing between the plate and a ground plane is around 0.1 times the central operating wavelength in free space. The large spacing and low-permittivity material limit the applications of some feeding structures used in conventional microstrip antennas with thin dielectric substrates. For example, a microstrip antenna can be fed by a microstrip line directly connected to the edge of radiator [1, 2] and also proximity-coupled by using a buried line below the radiating patch or a microstrip line through a non-resonance aperture [3][4][5]. Thus, a coaxial probe or a modified probe is a good candidate for an SPA. However, the long probe results in bad impedance matching due to large input inductance. To compensate for the inductance within a broad frequency range, some impedance-matching techniques, such as cutting a slot in the plate, inserting a 3D transition between the probe and plate, using a vertical ground plane, or introducing an electromagnetic coupling between the probe and plate have been developed [6 -19]. The On the other hand, the large spacing between the radiator and ground plane also provides the additional dimension needed to modify the feeding probe located under the radiating plate for improving the impedance matching [9,10]. Based on this idea, this paper describes a novel feeding structure for enhancing the impedance bandwidth of the SPA. This design features a copper sheet connecting a coaxial probe, instead of a thin cylindrical probe, to the radiating plate. This not only thickens the feeding probe, but also allows the SPA to be fed by a feeding...

FDTD Investigation on Bistatic Scattering From a Target Above Two-Layered Rough Surfaces Using Upml Absorbing Condition

“…s x and s y are only spatially variant along the x and y directions, and [16]. In Equation (4), the intermediate variables B x and B y are introduced as…”

“…There have been many absorbing boundary conditions developed to implement this in the FDTD method. Where, the UPML absorbing medium [16,17] are used to terminate the FDTD lattices, in which the finite-difference equations can be used for the total computation domain due to the fields satisfying Maxwell's equations (Ampere's and Faraday's laws). This makes the algorithm efficient since one does not have to take special care of the interface plane between the boundary and the interior regions.…”

Split-Field Finite-Difference Time-Domain Scheme for Kerr-Type Nonlinear Periodic Media

“…the splitfield formulation for linear media in [32]). We also assume Uniaxial Perfectly Matched Layer [37,38] (UPML) for the truncation in the z direction. The input plane wave source is excited in the structure following the schemes proposed in [23,39] for both continuous and time-limited pulsed waves.…”

Long-Time Stability and Convergence of the Uniaxial Perfectly Matched Layer Method for Time-Domain Acoustic Scattering Problems

“…Here G s is the fundamental solution of the Helmholtz equation satisfying the Sommerfeld radiation condition [28] 16) where K 0 (z) is the modified Bessel function of order zero. We follow the method of complex stretching [12] to introduce the PML equation in the frequency domain.…”