Introduction to the Physics and Techniques of Remote Sensing. Jakob J. van Zyl
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      where A is the wave amplitude, ω is the angular frequency, ϕ is the phase, and k is the wave vector in the propagation medium (imagesspeed of light in vacuum). The wave frequency ν is defined as ν = ω/2π.

      2.1.4 Quantum Properties of Electromagnetic Radiation

      The electromagnetic energy can be presented in a quantized form as bursts of radiation with a quantized radiant energy Q, which is proportional to the frequency ν:

      (2.11)equation

      where h = Planck’s constant = 6.626 × 10−34 joule second. The radiant energy carried by the wave is not delivered to a receiver as if it is spread evenly over the wave, as Maxwell had visualized, but is delivered on a probabilistic basis. The probability that a wave train will make full delivery of its radiant energy at some place along the wave is proportional to the flux density of the wave at that place. If a very large number of wave trains are coexistent, then the overall average effect follows Maxwell’s equations.

      2.1.5 Polarization

      An electromagnetic wave consists of a coupled electric and magnetic force field. In free space, these two fields are at right angles to each other and transverse to the direction of propagation. The direction and magnitude of only one of the fields (usually the electric field) is sufficient to completely specify the direction and magnitude of the other field using Maxwell’s equations.

      The polarization of the electromagnetic wave is contained in the elements of the vector amplitude A of the electric field in Equation (2.10). For a transverse electromagnetic wave, this vector is orthogonal to the direction in which the wave is propagating, and therefore we can completely describe the amplitude of the electric field by writing A as a two‐dimensional complex vector:

Graph depicts polarization ellipse.

      In the special case where the ellipse collapses to a line, which happens when δhδv = with n any integer, the wave is said to be linearly polarized. Another special case is encountered when the two amplitudes are the same (ah = av) and the relative phase difference δhδv is either π/2 or −π/2. In this case, the wave СКАЧАТЬ