A new efficient hybrid SBR/MoM technique for scattering analysis of complex large structures

An efficient hybrid analysis which hybridizes surface-wire integral equations (SWIE) with physical optics (PO) approximation is presented for wire antennas attached to an electrically large aircraft platform. In the analysis, the whole surface of the platform and antennas is divided into three regions, namely, the method of moments (MoM) region, the PO region and a region referred to as the joint PO-MoM (POM) region in this paper. The MoM region, generally, the smallest one among the three regions, includes wires, wire-surface junctions and a small part of the platform surface surrounding the junctions. A large part of the remaining platform surface forms the PO region with the rest being the POM region which is situated between the MoM and PO regions. The POM region is treated as a MoM region on the one hand so that the total MoM region is sufficiently large to well characterize the platform-attached antennas, whereas it is also regarded as a PO region on the other hand so that its interaction with the PO region needs not to be precisely considered so as to drastically reduce computational requirements.

An innovative and efficient hybrid technique, which combines the Method of Moments (MoM) with Volume Meshed Shooting and Bouncing Ray (VSBR), is presented to analyze the scattering of metallic–dielectric mixed multi-scale structures in urban scenes. Additionally, the technique can rapidly generate radar images at different angles, which is useful for the video remote sensing community. By dividing the mixed multi-scale targets into sub-regions, different solvers are employed to compute the scattering contributions based on their varying electrical sizes. For large-scale sub-regions, the VSBR method is employed on both the medium and metal parts, leading to a multilevel electromagnetic field including both the direct induced field and the multi-reflection field. This field contributes to the integral equation in the MoM sub-regions. Additionally, interactions from the MoM region are considered within the VSBR region, followed by a surface current integration to compute the scattered field. When addressing mixed multi-scale electromagnetic problems, this technique proves to be more efficient and easier to implement in general-purpose computer codes. Furthermore, this method is accelerated using the local coupling (LC) theory and fast multipole method (FMM). Using this fast computational method, efficient simulation results of radar images at different angles for the scenes can be obtained and the numerical results demonstrate the efficiency and accuracy of the proposed method.

These A new scattering analysis method combining the method of moment (MoM) and shooting and bouncing rays (SBR) method is presented for array structures above a rough surface. The array structures are analyzed using MoM with the characteristic modes (CMs) as the global domain basis functions. The rough surface and the mutual coupling between the array and the rough surface are modeled by the SBR. A numerical example is given to show the accuracy and efficiency of the proposed hybrid method.

Two ray shooting methods for computing the EM scattering by large open-ended cavities

Triangular ray tubes in electromagnetic scattering calculation using shooting and bouncing ray (SBR)

In this paper, an efficient higher order hybrid method of moments (MoM)-physical optics (PO) modeling technique is developed for the analysis of electromagnetic scattering from electrically large conductor objects. This technique utilizes curved triangular patches for geometric modeling, and higher order (HO) basis functions for current modeling, i.e., higher order hierarchical vector (HOHV) basis functions for MoM region and phase-extracted (PE) basis function for PO region. Benefitting from the “double” higher order discretization in both MoM and PO regions, the number of unknowns can be reduced remarkably, and the accuracy and efficiency increase, in comparison to the conventional low order MoM-PO solution. A numerical example is given to demonstrate the validity and efficiency of this HO-MoM-PO.

This paper presents an e-cient and accurate hybrid approach of method of moments (MoM) and physical optics (PO) for radiation problems such as antennas mounted on a large platform. The new method employs higher-order hierarchical Legendre basis functions in the MoM region and higher-order Nystrom scheme in the PO region. The two regions are both discretized with large domains. The unknowns can be much less than those in the small-domain MoM- PO solutions, which will lead to a great reduction in computation complexity. Furthermore, with the Nystrom scheme in the PO region, the higher-order accuracy is maintained, and the calculation of the impedances can be more e-cient than that in the existing higher- order MoM-PO procedure. Numerical results show the validity of the proposed method.

ABSTRACTA generalized hybrid scheme combining finite element method (FEM) and the method of moments (MOM) is first presented to investigate scattering from a 3-D dielectric object above a 2-D dielectric rough surface. The hybrid FEM/MOM scheme is divided into the FEM region for the object based on Helmholtz’s equation and the MOM region for the rough surface based on coupled integral function, which can greatly reduce the computed region. With the rough surface getting larger, the unknowns of the rough surface get more. So MLFMA is employed to reduce computation complexity of MOM region itself and coupling interaction matrices between MOM region and FEM region. Consequently, the iterative process can be greatly accelerated. This generalized hybrid FEM/MOM is very suitable for investigating scattering from composite model of a complex material object and electrically large dielectric rough surface. Some examples verify this generalized hybrid FEM/MOM in high efficiency, low storage requirement, high precision and generality.

The spectral theory of diffraction (STD) is well known for its ability to deal with complex fields (creeping waves, shadow limit fields, caustics fields) and their transformations through multiple diffractions. We present a fully numerical and 3-D implementation of this method. This implementation is based on a ray-tracing representation of plane waves propagation and it takes advantage of the simplicity of the plane waves transformation formulas at dielectric or conducting interfaces. The geometrical optics ray-tracing part of the procedure is quite similar to what is done in the shooting and bouncing rays (SBR) method, which has been applied to scattering calculations. However, the final evaluation of the field is performed through a spectral domain integration in our spectral domain ray tracing (SRT) method, instead of a physical optics integration in the SBR method. We give an outline of the principles of the method, and present the application of the method to substrate-lens antenna analysis. Simulated results obtained through this method are compared to results obtained through a more classical physical optics analysis, and to measured far-field radiation patterns of the antenna.

This paper analyzes the scattering characteristics of the hypervelocity models with the shooting and bouncing rays (SBR). The algorithm provides a reliable treatment to measure the object with electrically large size covered by inhomogeneous plasma sheath. The numerical results indicate that covering with plasma sheath will change the value of RCS of the hypervelocity. And the inhomogeneous plasma sheath also has great influence on the RCS result.

In this paper, an outdoor massive MIMO (Multiple-Input and Multiple-Output) system with $40\times 40$ planer array is simulated based on the SBR (Shooting and Bouncing Ray) method. The propagation characteristics, including PAP (Power Angle Profile), receive power, delay spread and PDP (Power Delay Profile), are studied in both LoS (line-of-sight) and NLoS (non-line-of-sight) links. The near-field effect is also discussed.

In the paper, high resolution range profile (HRRP) of a target above rough ground is analyzed based on the scattered echo data. The electromagnetic scattering of composite model is solved by the hybrid method of physical optics (PO)- shooting and bouncing ray (SBR). And an octree data structure is used to accelerate the ray tracing progress. The bistatic electromagnetic scattering of a reduced-scale vehicle target above rough ground is calculated by our method and compared with the simulation result with MLFMM in FEKO. Then by inverse Fourier transform of backscattering echo data, the range profile of composite model is obtained.

This paper proposes a method to compute the near-field RCS and Doppler spectrum of a target when the distances to the antennas are comparable to the target size. By dealing with a small piece of the target surface at a time, the transmitting antenna, and the receiving antenna are in the far-field zone of the small piece of the induced currents. The electromagnetic field produced by this small piece of induced currents can be written as a spherical wave. Sum up all spherical waves produced by every small piece of induced currents and we can obtain the total scattered field at the receiving antenna. The physical theory of diffraction (PTD) and the method of shooting and bouncing rays (SBR) are modified to evaluate the received signals. Numerical results based on these techniques are obtained and discussed. The formulation applies the simple concepts of "equivalent" image and vector effective height, which are believed to be novel.

Radar detectability reducing for complex shape military or civil object is very important problem of contemporary radar theory. Solution of this problem is unthinkable without providing numerical estimations of the investigated object Radar Cross Section (RCS) and its reduction with some cloak. In this paper a new method for the semitransparent cloak modeling is proposed. This method is realized in the framework of Shooting and Bouncing Ray (SBR) method. General stages of SBR method and the cloak modeling introduction into its algorithm are discussed. The proposed approach was tested on an example of complex shape object.

This letter proposes new usage of the binary tree constructed by fundamental GO ray components in shooting and bouncing rays (SBR) for indoor propagation analysis. The node number of the binary tree is here considered as an important parameter. A couple of small size arrays that can store the passing ray information of both the node number and the position of the pixel considered, and the corresponding ray classification algorithm are newly introduced, not to double-count the same ray with slightly different bouncing angle. Consequently, we realize the big reduction of the computer memory resources consumed for the ray classification especially for wide area analysis, keeping the high accuracy of the SBR method.