Electromagnetic scattering from buried objects

Abstract

Radar imaging and detection of objects buried in soil has potentially important applications in the areas of nonproliferation of weapons, environmental monitoring, hazardous-waste site location and assessment, and even archeology. In order to understand and exploit this potential, it is first necessary to understand how the soil responds to an electromagnetic wave, and how targets buried within the soil scatter the electromagnetic wave. We examine the response of the soil to a short pulse, and illustrate the roll of the complex dielectric permittivity of the soil in determining radar range resolution. This leads to a concept of an optimum frequency and bandwidth for imaging in a particular soil. We then propose a new definition for radar cross section which is consistent with the modified radar equation for use with buried targets. This radar cross section plays the same roll in the modified radar equation as the traditional radar cross section does in the free-space radar equation, and is directly comparable to it. The radar cross section of several canonical objects in lossy media is derived, and examples are given for several objecdsoil combinations.

A study on the possibility of applying precursor waves to penetration imaging

“…Figure 3 illustrates the propagation of rectangular pulses with 500MHz and 1GHz carrier frequencies in different soils. Their model parameters are from [6]: the water contents are 5%, 10% and 20%, respectively; the dry densities are 3 /cm g .2 1 , 3 /cm g .6 1 and 3 /cm g . 8 1 , respectively.…”

“…For typical dielectric materials of interest in remote sensing, such as water and specific soils, the multirelaxation Debye model can be used to describe the relative permittivity as [6] . In order to describe soils' dispersive permittivity with the physical parameters, Dobson and Ulaby extended Birchak's mixture model as [7] )…”

Introduction of Oblique Incidence Plane Wave to Stratified Lossy Dispersive Media for FDTD Analysis

“…The dielectric properties of many dispersive media of interest in remote sensing, such as water and soil, can be described by Debye model [2], [20], [21]. Since this model is appropriate for FDTD computation, the following discussions are based on it.…”

“…1, can be evaluated according to (3). The fields at can be evaluated by (20) Similar formulation can be implemented to solve the fields at .…”

“…6. [20] The dispersive permittivity of the sand and soil is modeled with (1). The parameters are listed in Table I.…”