Multiple phase screen calculation of wide bandwidth propagation

Abstract

This paper presents results from a two‐dimensional multiple phase screen (MPS) calculation that computes numerical realizations or sample functions of the electric field after propagation through the ionosphere. The MPS code solves the parabolic wave equation and allows for direct computation of realizations of the received signal. The ionization is represented by a series of random phase screens that characterize the severity and spectrum of the electron density fluctuations. For wide bandwidth signals, the MPS code is exercised for many frequencies over the bandwidth of the propagating signal; Fourier transform techniques are used to obtain the propagating signal in the time domain. The MPS simulation is quite general and may be applied to problems involving numerous, separated, layers of ionization characterized by spatially varying electron density power spectra. MPS techniques can handle all levels of ionospheric disturbances from the least severe, where only small phase fluctuations occur, to the most severe case of frequency selective scintillation. Several examples of propagating signals are presented that simultaneously show the development of the ionospheric transfer function and the impulse response function. The calculations are repeated, and the realizations are averaged to obtain the two‐frequency, two‐position mutual coherence function (MCF), Γ( x , f ) and its Fourier transform S ( q , τ ), the generalized power spectrum. The wide bandwidth MPS results closely match results obtained from strong scatter theory as utilized in the phase screen diffraction method.