An efficient and accurate technique for the incident-wave excitations in the FDTD method

Abstract

Cataloged from PDF version of article.An efficient technique to improve the accuracy\ud of the finite-difference time-domain (FDTD) solutions employing\ud incident-wave excitations is developed. In the separate-field\ud formulation of the FDTD method, any incident wave may be\ud efficiently introduced to the three-dimensional (3-D) computational\ud domain by interpolating from a one-dimensional (1-D)\ud incident-field array (IFA), which is a 1-D FDTD grid simulating\ud the propagation of the incident wave. By considering the FDTD\ud computational domain as a sampled system and the interpolation\ud operation as a decimation process, signal-processing techniques\ud are used to identify and ameliorate the errors due to aliasing.\ud The reduction in the error is demonstrated for various cases. This\ud technique can be used for the excitation of the FDTD grid by any\ud incident wave. A fast technique is used to extract the amplitude\ud and the phase of a sampled sinusoidal signal

Reducing the Dispersion Errors of the Finite-Difference Time-Domain Method for Multifrequency Plane-Wave Excitations

“…In Oguz, Gürel, and Arıkan (1998), it was shown that increasing the resolution of the 1-D source grid decreased the error on the phase velocity of each frequency component in the source function. A transient pulse contains more frequency components compared to a sinusoidal function.…”

“…Assume that the already-sampled signal is downsampled (decimated) by a factor of M. The resulting lower sampling rate scales the spectrum of the original signal M times wider and may cause aliasing (Oguz, Gürel, & Arıkan, 1998;Oppenheim & Schafer, 1989). In order to prevent the aliasing, a digital lowpass filter should be employed on the signal before the decimation to reduce the bandwidth below In contrast to the decimation operation, interpolating new values from the existing samples of a signal does not cause aliasing since the band of resolved frequencies increases with the increased sampling rate.…”

“…These errors can be observed in the form of nonphysical DC offsets, signal distortions, and added noise (Umashankar & Taflove, 1982;Taflove & Umashankar, 1983;van Gennip, 1992;Furse, Mathur, & Gandhi, 1990). In Gürel and Oguz (2000), Oguz, Gürel, and Arıkan (1998), and Oguz and Gürel (1997), the applications of the aforementioned SP techniques were demonstrated for FDTD computations with sinusoidal excitations. This article shifts the focus to the application of the SP techniques to transient signals with arbitrary spectra.…”

Analysis of Tf-Sf Boundary for 2d-FDTD With Plane P-Wave Propagation in Layered Dispersive and Lossy Media

“…It is worth pointing out that there is not any approximation, such as narrow band restriction, because of the θ in(9) being the incident angle other than the transmission angle in [4], required while the auxiliary variable H z1D in Equation (7) is implemented. In 2D-FDTD, the simulation of plane wave along side TF-SF boundary at i = i r should especially treat the field component of H z (i r , j) and E y (i r + 1/2, j) in expressions (2) and(4), they need the incident wave component of E y (i r + 1/2, j) and H z (i r , j) respectively, but the expressions (8) and (10) (8) and (10), the right TF-SF boundary is treated completely. The treatment to left boundary near i = i l is similarly.…”

Optimization of Excitation in FDTD Method and Corresponding Source Modeling

“…The TF/SF technique showed very good performance in FDTD modeling of long-duration pulsed or continuous wave excitation and it is widely used in guided-wave simulations [1]. The TF/SF technique has been extensively studied in the literature and many modifications and improvements of this basic method can be found [6][7][8][9].…”