GO/PO and PTD With Virtual Divergence Factor for Fast Analysis of Scattering From Concave Complex Targets

Abstract

Due to simplicity, hybridization of geometrical optics (GO) and physical optics (PO) based on ray tracing has been widely used for fast scattering analyses. However, when targets of curved concavities are discretized by flat facets, the loss of divergence factor (DF) will degrade the simulation accuracy. To remedy this loss, a simple and efficient factor, entitled virtual divergence factor (VDF), is proposed to play the role of DF. To prove the validity of VDF and simulate the scattering of concave complex targets, a hybrid method of GO/PO and physical theory of diffraction (PTD) is elucidated. With VDF correction, several typical targets, including a S-shape cavity, are simulated by this hybrid method. In comparison to multilevel fast multipole algorithm (MLFMA) or measurements, the validaty of VDF is fully demonstrated by good agreements and the excellent performance relative to DF on canonical surfaces, where the great efficiency and flexibility of this hybrid method are also shown. Moreover, one interesting and important issue, the dependance of field convergence on the maximum number of ray reflections, is also investigated for the first time.

Efficient Meshing Scheme for Bodies of Revolution-Application to Physical Optics Prediction of Electromagnetic Scattering

“…Multiple reflections that occur in complex geometries are included via the well-known multiple GO + PO approach [20]. The code includes the effect of surface curvature on the electromagnetic field amplitude in multiple reflections [21,22] and calculates the diffraction and reflection-diffraction fields via the Method of Equivalent Currents [23]. In order to verify the proposed meshing algorithm, scattering from two typical benchmark objects are studied and compared with experimental data and numerical methods.…”

The influence of mesh fineness on virtual divergence factor for high frequency methods in electromagnetic scattering

“…the flexible triangular mesh, (DF) j will be always equal to unity for arbitrary j, which results into the overestimation or underestimation of RCS. As noted above, this error can be corrected by VDF [7], according to which LjCOSaj L j+ 1 COS aj+ 1…”

“…Due to simplicity and the capability to tackle multiple scattering, high frequency hybrid methods of geometrical optics (GO) and physical optics (PO) [1] based on ray tracing have been widely utilized for fast electromagnetic simulations [2]- [7]. Generally, these hybrid methods involve two parts: ray tube tracing and electromagnetic computation.…”

“…Snell's law [3], where kd-tree might be utilized to accelerate this process [5]- [7]. In the latter part, the field amplitude of each center ray at every reflection is computed via GO.…”

“…Recently, a new and efficient factor, entitled virtual divergence factor (VDF), has been proposed to play the role of DF [7]. Compared with the interpolation algorithm, VDF needs remarkably much lower computational costs.…”