Date of Award

11-9-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Electrical and Computer Engineering

First Advisor

Andrew J. Terzuoli, PhD

Abstract

The ionosphere has significant impact on radio frequency (RF) applications such as satellites, over-the-horizon radar, and commercial communication systems. The dynamic processes effecting the behavior of the ionic content leads to a variety of instabilities that adversely affect the quality of RF signals. In the F-layer ionosphere, flute instability persists, appearing as two radial regions of high and low density perturbations elongated along the earth's geomagnetic field lines. The sizes of flute structures are comparable to the wavelengths in the high frequency spectrum. The objective is to characterize the high frequency scattering of an incident field by developing a 3D propagation model that incorporates a phase cube coupled ray tracer approach to discretize the phase effects of a two-fluid magnetohydrodynamic (MHD) dipole flute density perturbation model. A single fluid MHD model simulates a variety of plasma flow and shear effects to alter the ideal flute's physical features, creating a subset of unique flutes. A unique phase screen approach is presented to generate stochastic flute density maps. The phase power spectrums reveal a power law relationship similar to Kolmogorov turbulence. The electric field propagation results demonstrate that specific arrangements of the flutes can cause weak to strong scattering conditions. Additional frequency domain analysis of the received field scattering functions demonstrates the existence of parabolic scintillation arcs, significant broadening in the doppler power spectrum, and narrow coherence bandwidths indicating frequency selectivity in the propagation channels that adversely impact the quality of high frequency electric fields.

AFIT Designator

AFIT-ENG-DS-21-D-009

DTIC Accession Number

AD1157027

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