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Full-Text Articles in Physics

A Review Of High Frequency Radio Wave Absorption, David Alan Smith Dec 2016

A Review Of High Frequency Radio Wave Absorption, David Alan Smith

David Smith

Although the technology dates back nearly to Marconi and his wireless telegraph, the high-frequency (HF) radio spectrum continues to be a useful communications medium.  Since long-distance HF propagation depends on the ionosphere, HF propagation is subject to variations in ionospheric characteristics.  Chief among these characteristics is the density of free electrons.  The sun provides the energy required to ionize neutral atmospheric constituents.  Hence, the production and loss of free electrons is not constant.  Day/night variations as well as the ebb and flow of the 11-year solar cycle cause changes in the density of free electrons.  In addition, space weather ...


High-Frequency Radio Wave Absorption In The D-Region, David Alan Smith Dec 2016

High-Frequency Radio Wave Absorption In The D-Region, David Alan Smith

David Smith

Polar Cap Absorption (PCA) events are triggered by highly-energized solar particles gaining access to upper regions of Earth's atmosphere at high latitudes.  These energized particles can be the result of solar flares and coronal mass ejections.  PCA events are associated with significant attenuation of high-frequency radio signals propagating through the ionosphere via paths over polar regions.  However, the degree to which these events depend on solar wind parameters is not fully understood, nor is their impact on high-frequency (HF) radio communications.  As a first step in understanding the mechanisms of PCA events, a thorough study of HF radio wave ...


High-Frequency Radio Wave Absorption In The D-Region, David Alan Smith Dec 2016

High-Frequency Radio Wave Absorption In The D-Region, David Alan Smith

David Smith

Although the technology dates back nearly to Marconi and his wireless telegraph, the high-frequency (HF) radio spectrum continues to be a useful communications medium.  Since long-distance HF propagation depends on the ionosphere, HF propagation is subject to variations in ionospheric characteristics.  Chief among these characteristics is the density of free electrons.  The sun provides the energy required to ionize neutral atmospheric constituents.  Hence, the production and loss of free electrons is not constant.  Day/night variations as well as the ebb and flow of the 11-year solar cycle cause changes in the density of free electrons.  In addition, space weather ...