kokonaiskenttää

Kokonaiskenttä, or total field, refers to the complete wave field in a region of space produced when a wave interacts with an object or inhomogeneity. It is the sum of the incident field, which is the externally applied or incoming wave, and the field scattered by the object. In electromagnetism, acoustics, and quantum scattering, the total field satisfies the appropriate wave equation with boundary conditions on the object's surface. The incident field is known a priori; the scattered field arises from the interaction and carries information about the object's size, shape, and material properties.

In practical terms, the total field enables calculation of observable quantities such as the far-field scattering amplitude, differential and total cross sections, or radar cross section, as well as near-field distributions relevant for sensing and imaging. The total field is used both to solve forward scattering problems (predicting the field for a given object and incident wave) and to address inverse problems (recovering object properties from measured fields).

Common computational approaches include Mie theory for spherical objects, T-matrix methods for nonspherical particles, and numerical techniques such as boundary element, finite element, and finite-difference time-domain methods. In quantum mechanics, the concept appears as the total wave function, often written as the sum of an incident plane wave and a scattered component, used to derive scattering amplitudes and cross sections.