Numerical calculation of diffraction coefficients of generic conducting and dielectric wedges using FDTD

Abstract

Classical theories such as the uniform geometrical theory of diffraction (UTD) utilize analytical expressions for diffraction coefficient for canonical problems such as the infinite perfectly conducting wedge [1]. In this paper, we present a numerical approach to this problem using the finite-difference timedomain (FDTD) method. We present results for the diffraction coefficient of the two-dimensional (2-D) infinite perfect electrical conductor (PEC) wedge, the 2-D infinite lossless dielectric wedge, and the 2-D infinite lossy dielectric wedge for incident TM and TE polarization and a 90 wedge angle. We compare our FDTD results in the far-field region for the infinite PEC wedge to the well-known analytical solutions obtained using UTD. There is very good agreement between the FDTD and UTD results. The power of this approach using FDTD goes well beyond the simple problems dealt with in this paper. It can, in principle, be extended to calculate diffraction coefficients for a variety of shape and material discontinuities, even in three dimensions.

Efficient modeling of infinite scatterers using a generalized total-field/scattered-field FDTD boundary partially embedded within PML

“…We now compare the G-TF/SF-computed diffraction coefficients using the method described in [3] for the infinite 45 -angle PEC wedge with the well-known asymptotic diffraction coefficients [4], [5] arising in the uniform theory of diffraction (UTD) . Fig.…”

“…Thus, the G-TF/SF formulation can be used to efficiently model infinite scatterers illuminated by plane waves in a relatively small grid. Previously proposed FDTD-based methods rely completely on the conventional TF/SF formulation and a time-gating procedure [3] to model infinite scatterers illuminated by plane waves within a finite FDTD grid. However, depending on the source angle and the observation points, this approach may require the use of a very large scatterer in the FDTD grid in order to permit time-gating.…”

Review of the Hidden Rays of Diffraction

“…Therefore, it is impossible to see these rays in the physical region. Thus, these extraordinary rays are called hidden rays [5].…”

“…Recently, the finite difference time domain (FDTD) method has been employed to calculate the diffraction coefficients of penetrable wedges numerically without any analytical treatment [5]. However, the fully numerical approach could not provide any physical understanding of the inherent features in the wedge diffraction.…”

Numerical calculation of diffraction coefficients from building edges using FDTD method

“…Diffraction coefficient can be found numerically by using FDTD method from equations (2.3) and (2.6) for PEC wedge in frequency domain [10].…”