Introduction and History Electromagnetic Wave Propagation
Attenuation
![[Under Construction]](images/undercon.gif){kind=small}
Attenuation describes how energy is lost or dissipated. Energy loss occurs as a transformation from one type of energy to another. Thus, electromagnetic energy may be converted to thermal energy (or heat). Loss is the cost of moving something, like charges or particles. Things in motion are described by a thermodynamic temperature, and at absolute zero (0 K) nothing moves. Loss always results in frequency dependent properties (dispersion) as things always move with finite velocities. Complex magnetic permeability and complex dielectric permittivity have real and imaginary parts of the complex quantities used to describe the storage (real part) and loss or transformation (imaginary part) of energy. Attenuation describes intrinsic losses that result from things moving and the resultant losses are exhibited as temperature rise, but also may be used (as apparent attenuation) to describe energy that is lost through geometric effects. Such apparent losses are the result of geometric spreading, surface and volume scattering, waveguides and multipathing. In the latter case, the energy is not transformed to heat and is still electromagnetic, but it is following a path that is no longer useful or observable. Electrical conduction losses are caused by charge motion and are equivalent to the losses in the imaginary part of the complex dielectric permittivity. (See charge demonstration program.)
(figure of exponential decay)
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