Introduction and History Electromagnetic Wave Propagation
Velocity Wavelength Attenuation Dispersion
Rocks, Soils and Fluids: Electrical Properties Magnetic Properties
Environmental Influences of Temperature, Pressure, Chemistry and Time
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Most environmental influences impact ground penetrating radar through changes in electrical properties. Little influences the magnetic properties except for the presence, volumetric abundance, and oxidation state of iron. Though with the right titanium concentration and mineralogy in iron oxides, the Curie temperature can be in the range of daily weather and annual climate changes, causing day-night or winter-summer changing contributions from magnetic properties. Temperature mostly impacts ground penetrating radar by modification of the properties of water from liquid to solid (ice) or vapor (steam). Pressure causes effects through stress applied to the material, and can be a strong influence when such effects include the opening and closing of cracks or changing of pore spaces. Chemistry mostly impacts ground penetrating radar also by modification of the properties of water. Changing pH and salinity of the water can change the freezing point, electrical conductivity, wettability, and mineral-water interfacial electrochemistry. Most changes related to water are seen as the result of changing seasons (wet-dry or freeze-thaw), seawater intrusion, or rainfall events. The combinations of chemistry (salinity), temperature, and rate of change of temperature during freezing significantly alters the bulk properties as well as the heterogeneity and texture (hence the scattering) of materials like sea ice or permafrost. The volumetric replacement of water by hydrocarbons or organic chemical contaminants may also alter the observed radar response. This may be direct due to the difference in dielectric permittivity but may also be more subtle as in the change of textural scattering due to differing wettabilities of the soil between water and hydrocarbon. Some materials also exhibit differing properties as a function of time, such as curing and aging in concrete and grouts, or devolatilization, oxidation and biodegradation of hydrocarbons. The influence of time also appears as frequency dependent behavior of material properties through the finite velocity of charge motion in response to the application of external electromagnetic fields.
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Heterogeneity, Anisotropy and Scale Radar Equation
Scattering Polarization Fresnel Reflection Snell Angle Stokes-Mueller Matrices Poincare Sphere
Antennas Coupling Near / Far Fields Waveguides Multipathing Resonance
Survey Design Contrast Geometry Resolution Depth of Investigation Orientation
Data Acquisition Data Processing Modeling Interpretation Uncertainty
Applications: Noninvasive Surface Borehole Airborne Satellite and Space