RegisterWave polarizationPolarization describes the orientation of the electric field intensity vector of an electromagnetic wave. If wave propagates in free space, linear or elliptic polarization can exist. The wave is linearly polarized if the vector E is oriented to the same direction during the whole time period. If an arrow represents instantaneous intensity vector, then its length changes from zero to maximum and back during the half-period. During the second half-period, the described phenomenon repeats with an opposite polarity. The ending point of the arrow moves along a line. If the wave is of elliptic polarization, then the electric field intensity vector changes its direction during the time period. The arrow representing the instantaneous intensity vector rotates during the period, and at the same time, changes its length that way, that the ending point moves along the ellipse. The ellipse is run around within one period exactly. In a special case, the ending point can move along the circle (circular polarization). Elliptic (circular) polarization can be of clockwise or anti-clockwise nature. The sense of rotation is determined from the direction of wave propagation. Elliptically polarized wave can be understood as a superposition of two coherent linearly polarized waves, which vectors E oscillate in different directions and a non-zero mutual shift. If the wave propagates near the plane of boundary of two media, we distinguish between the perpendicular polarization and the parallel one. Let us define the plane of incidence: it is a plane, which is perpendicular to the plane of boundary, and at the same time, is parallel to the wave propagation. The vector E of the perpendicularly polarized wave is perpendicular to the plane of incidence. The vector E of the parallel-polarized wave is parallel to the plane of incidence. If the plane of boundary is identical with the earth surface, then the perpendicularly polarized wave is denoted as horizontally polarized, and the parallel-polarized wave is called vertically polarized one. Back
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