Analysis of Sweep Frequency Oblique Polar Region High Frequency Radio Propagation Measurements.

摘要

The Chapman-Davies-Littlewood technique for the computation of the equivalent path of an ionospherically propagated High Frequency (HF) radio signal was used to determine the most probable modes of oblique propagation and the corresponding frequency windows that existed during six experimental aircraft flights in the polar region. In comparison to these results,the Elkins-Rush HF Polar Predictive Model has been found to be inadequate for short-term propagation predictions. These oblique propagation measurements have verified Feldstein and Starkov's conclusion that the magnetic Index Q is a good indicator of the position,shape,and size of the Instantaneous Auroral Oval as they have defined it on the basis of ground-based optical measurements which they subjected to statistical analyses. An approach has been developed which sheds new light on the behavior of HF signals propagating via the polar ionosphere. On the basis of the results achieved using this approach,it is recommended that an attempt be made to develop a new method of predicting short-term polar region HF propagation conditions well in advance (that is,an hour or more in advance in real time). A hypothetical example of an application of such a method is given. Action should be taken soon to exploit this possibility. Additional work could extend the applicability of this approach beyond anything that has seemed feasible before. New understanding of the physics of the polar ionosphere could result. It is hoped that this report will stimulate the experimental and theoretical research that will result in this increased understanding of the polar ionosphere. (Author)