Comparison between the extendedmedium and the phasescreen scintillation theories
Abstract
By numerically solving the fourth moment equation, comparisons are made between situations in which fluctuations of refractive index extend uniformly from the transmitter to the receiver and situations in which the fluctuations are confined to a phase screen. The comparisons are made for inverse powerlaw phase spectra having a total meansquare fluctuation of phase = (Delta Phi)sq, an outer scale L0 and an inner scale 0.01 L0. Four values of the spectral index are investigated, including the Kolmogoroff value. The comparisons are made for a wavelength such that the Fresnel scale is intermediate between the outer scale and the inner scale, so that both refractive and diffractive scattering are involved. The study extends from situations dominated by weak diffractive scattering up to ones dominated by multiple refractive scattering. It is found that, provided that the equivalent screen is centrally located, has the same type of fluctuation spectrum, and generates the same mean value of (Delta Phi)sq as the extended medium, then the scintillation index and the intensity autocorrelation function in the reception plane are approximately the same in the two cases. Results are very dependent on how many refractive scatterings occur between the transmitter and the receiver, but they are not very dependent on how these refractive scatterings are distributed along the path.
 Publication:

Journal of Atmospheric and Terrestrial Physics
 Pub Date:
 April 1985
 DOI:
 10.1016/00219169(85)900182
 Bibcode:
 1985JATP...47..381B
 Keywords:

 Fresnel Diffraction;
 Method Of Moments;
 Phase Shift;
 Power Spectra;
 Scatter Propagation;
 Scintillation;
 Autocorrelation;
 Difference Equations;
 Differential Equations;
 Ionospheric Propagation;
 Kolmogoroff Theory