Introduction and History Electromagnetic Wave Propagation
Velocity Wavelength Attenuation
Dispersion
![[Under Construction]](images/undercon.gif){kind=small}
Dispersion is the change in shape of a propagating wavelet as a result of frequency dependent material properties. Earth materials generally act like low pass filters, so dispersion causes pulse broadening and phase delay. Dissipative loss mechanisms such as electrical conduction and magnetic or dielectric relaxation will cause dispersion, as will surface or volume scattering from heterogeneities on a scale close to the wavelength of propagation in the material. Multipathing and waveguiding may also cause apparent dispersion, though multipathing causes changes in wavelet shape through constructive and destructive interference, not by frequency dependent properties. Most dispersive effects in the earth are caused by the motion of water.
(animation showing increasing loss causing increasing frequency dependence and pulse dispersion (from GRORADAR))
(figure of frequency dependent properties)
Rocks, Soils and Fluids: Electrical Properties Magnetic Properties
Environmental Influences 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