Exact ray path calculations using realistic ionospheres
The paper discusses a technique for fitting quasiparabolic layers to measured vertical electron density profiles. The method adopted is to represent individual ionospheres by the appropriate combination of E, E-F valley, F1 and F2 layers connected by joining layers. The method produces quite accurate representations of measured ionospheric profiles. The advantage of using quasiparabolic layers is that analytical solutions of various ray parameters can be obtained, including the effect on signal strength of ray tube divergence. Furthermore, tilted ionospheres can also be considered. The methods are illustrated by application to two vertical electron density profiles obtained from the same ionogram. The primary difference in the profiles is that one contains an E-F valley. Results are presented showing not only the effects of the profile differences, but also the effects of tilts, antenna patterns and ionospheric absorption.
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