Electromagnetic field and material properties in ground penetrating radar

Electric, magnetic and electromagnetic fields are consequences of the existence, motion and acceleration of electric charge. Complex coupled vector field distributions in space and time result. Most material properties are consequences of EM field interactions between adjacent matter particles at atomic scales. Velocity, attenuation, wavelength, polarization, scattering, relaxation, and resonance are some of the properties and processes important to electromagnetic wave propagation in ground penetrating radar. Such properties and processes determine the performance limitations of ground penetrating radar systems, and they are also what are measured by ground penetrating radar to describe ground and things buried within the subsurface. Space and time distributions of material properties are described in terms of complex dielectric permittivity and complex magnetic permeability. "Complex" means there are parts describing both energy dissipation and storage, with consequential frequency dependent properties. Dielectric properties are dominantly controlled by the distribution and properties of water in the ground. Magnetic properties are dominantly controlled by the distribution and properties of iron in the ground. Field polarization and scattering processes are dominantly controlled by the geometric orientation and spatial distribution of contrasts in material properties at wavelength scales. Measurement of field properties and processes allows GPR to determine material properties.