Fluence rate is wholly non-directional and includes UV radiation over 4[pi] steradians
; that is, all of the possible directions from which UV rays might originate are included, and the influence of UV radiation received by the specified point is independent of direction.
Therefore the distribution of the first surface reflectance is determined by the distribution of the micro-facet normals which in turn is driven by the density function [equivalent to] ([THETA]), the relative density of micro-facet normals (per steradian
) in vector direction [THETA].
where: F = flux density (W/[m.sup.2]-Hz) k = Boltzmann's constant (1.38 x [10.sup.-23] J/K) T = physical temperature of the blackbody (K) [lambda] = wavelength of the RF radiation (m) and [omega] = solid angle subtended by the blackbody source (steradians
If the communication requirement is for the entire quadrant (hemispherical coverage), the function is normalized by [Pi]/2, the solid angle in steradians
in a single quadrant.