Characteristics of the Earth-ionosphere Waveguide for VLF Radio Waves


Book Description

The principal results of this technical note are graphical presentations of the attenuation rates, phase velocities, and excitation factors for the dominant modes in the earth-ionosphere waveguide.The frequency range considered is 8 kc/s to 30 kc/s. *The model adopted for the ionosphere has an exponential variation for both the electron density and the collision frequency, and the effect of the earth's magnetic field is considered.Comparison with published experimental data confirms that the minimum attenuation of VLF radio waves in daytime is approximtely at 18 kc/s, while at night it is somewhat lower.The directional dependences of propagation predicted by the theory are also confirmed by experimental data.(Author).













Mode Calculations for Vlf Propagation in the Earth-Ionosphere Waveguide (Classic Reprint)


Book Description

Excerpt from Mode Calculations for Vlf Propagation in the Earth-Ionosphere Waveguide Nbs Technical Notes are designed to supplement the Eu reau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be listed or referred to in the open literature. They are for sale by the Office of Technical Services, U. S. Depart ment of Commerce, Washington 25, D. C. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.







Propagation Characteristics of VLF Waves Below a Stratified and Generally Anisotropic Ionosphere


Book Description

The research constitutes one method of formulation for the calculation of very low frequency radio wave propagation characteristics of the earth-ionosphere waveguide. It involves a brief consideration of some general properties of the ionosphere which influence the propagation of VLF (very low frequencies) waves. In the analysis, the waveguide is the area formed by the earth and the lower conducting region of the ionosphere. The propagation characteristics are obtained from the solution of a modal equation which is formulated directly in terms of the reflection coefficients of both the ionosphere and earth. The coupled vacuum mode theory of Poeverlein is extended to include the earth's curvature effects by assuming the ionosphere as a cylindrical stratified medium. The modal equation is solved by an iterative procedure and propagation characteristics are obtained for a variety of ionospheric conditions for different directions of propagation. A comparison of the numerical results is made with different formulations in the literature. (Author).