Search

Abstract Here, the multibranch linear–linear basis function (MB‐LL) is applied to the Poggio–Miller–Chang–Harrington–Wu–Tsai equation for calculating the scattering problem of multi‐scale dielectric targets. The MB‐LL basis function replaces the positive and negative triangles of the traditional linear–linear basis function (LL) with multiple branches, so it can be used at the junction of the meshes of different size. By using the MB‐LL basis function, we can easily divide the calculation region into several non‐overlapping regions, which is very suitable for the simulation of multiscale targets. At the same time, the MB‐LL basis function inherits the properties of the LL basis function, which is more accurate than the multibranch Rao–Wilton–Glisson (MB‐RWG) basis function. Numerical examples demonstrate the advantages of the proposed method.

Computing the Radar Cross-Section (RCS) of a given object is a topic of major importance for many applications, e.g., target detection and stealth technology. In this context, high-frequency asymptotic methods are widely used. In this article, we derive a Gaussian Beam Summation (GBS) method for both metallic and dielectric targets. The basic idea is to use the GBS method to compute the scattering far fields generated by the equivalent currents flowing on the surfaces. The validity of the proposed method is then investigated in the X-band. To accomplish this, the results obtained using this technique were compared to those obtained using other sufficiently accurate methods such as the ray tracing of FEKO and the ray asymptotic solution. As an example of the method’s accuracy, the GBS method was used to obtain the wave field in a homogeneous medium by fitting the results to a point source. In the same way, the method was used to compute the RCS of dielectric cuboids.

Bistatic scattering coefficient have important application of ocean active microwave remote sensing. In this paper, a general expression of the composite scattering coefficient for multiple dielectric targets of one-dimensional fractal sea surface is derived by MOM method. Secondly, the bistatic scattering coefficient is computed, there are two class missile targets and one class ship target of one-dimensional fractal sea surface, and the influence of the water dielectric constant, fractal dimension, wind speed, the target dielectric constant and spatial position is discussed, and the corresponding conclusions are given. The proposed algorithm is able to solve some composite scattering problems, such as 'dielectric or conductive object + rough surface', 'dielectric or conductive floating object +rough' and it has certain generalization and reference, and it lays a foundation for solving the composite scattering coefficient of multiple medium targets in two-dimensional fractal sea surface. [ABSTRACT FROM AUTHOR]

The terahertz scattering characteristics of metallic and dielectric rough targets is important for the investigation of the terahertz radar targets properties. According to the stationary phase theory and scalar approximation, if the radius of curvature at any point of the surface is much larger than the incident wavelength, and the wavelength is also much longer than the surface height function and Root-Mean-Square (RMS) surface slope, the coherent and incoherent scattering Radar Cross Section (RCS) of rough metallic and dielectric targets can be obtained. Based on the stationary phase approximation, the coherent RCS of rough conductors, smooth dielectric targets and rough dielectric targets can be easily deputed. The scattering characteristics of electrically large smooth Al and painted spheres are investigated in this paper, and the calculated RCS are verified by Mie scattering theory, the error is less than 0.1 dBm2. Based on lambert theory, it is demonstrated that the incoherent RCS is analyzed with better precision if the rough surfaces are divided into much more facets. In this paper, the coherent and incoherent scattering of rough Al and painted spheres are numerically observed, and the effects of surface roughness and materials are analyzed. The conclusions provide theoretical foundation for the terahertz scattering characteristics of electrically large rough targets.

Here, the multibranch linear–linear basis function (MB‐LL) is applied to the Poggio–Miller–Chang–Harrington–Wu–Tsai equation for calculating the scattering problem of multi‐scale dielectric targets. The MB‐LL basis function replaces the positive and negative triangles of the traditional linear–linear basis function (LL) with multiple branches, so it can be used at the junction of the meshes of different size. By using the MB‐LL basis function, we can easily divide the calculation region into several non‐overlapping regions, which is very suitable for the simulation of multiscale targets. At the same time, the MB‐LL basis function inherits the properties of the LL basis function, which is more accurate than the multibranch Rao–Wilton–Glisson (MB‐RWG) basis function. Numerical examples demonstrate the advantages of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the results from the computational investigation of the effect of a metal grounded target, metal target at a floating potential and dielectric targets (conductive and non-conductive) on the plasma bullet propagation and reflection. We show that the intensity of the primary ionization wave (IW) is the highest for the metal target, while it is significantly lower for the non-conductive dielectric. For the conductive dielectric, the wave intensity is greater than that for the non-conductive dielectrics, but lower than for a metal target. After the primarily forward IW touches the target, the reflected waves are observed for all the targets under investigation. For a metal target the reflected IW changes its direction and transforms into the secondary forward wave. We did not observe secondary forward IWs for dielectric targets. For dielectric targets, the reflected waves gradually decayed without changing their direction. The 'stopping' path for the reflected wave is introduced and the increase/decrease of this path is discussed in dependence on the target properties. [ABSTRACT FROM AUTHOR]

Effective diagnostics with ground penetrating radar (GPR) is strongly dependent on the amount and quality of available data as well as on the efficiency of the adopted imaging procedure. In this frame, the aim of the present work is to investigate the capability of a typical GPR system placed at a ground interface to derive three-dimensional (3D) information on the features of buried dielectric targets (location, dimension, and shape). The scatterers can have size comparable to the resolution limits and can be placed in the shallow subsurface in the antenna near field. Referring to canonical multimonostatic configurations, the forward scattering problem is analyzed first, obtaining a variety of synthetic GPR traces and radargrams by means of a customized implementation of an electromagnetic CAD tool. By employing these numerical data, a full 3D frequency-domain microwave tomographic approach, specifically designed for the inversion problem at hand, is applied to tackle the imaging process. The method is tested here by considering various scatterers, with different shapes and dielectric contrasts. The selected tomographic results illustrate the aptitude of the proposed approach to recover the fundamental features of the targets even with critical GPR settings.