Measurement and modelling of HF channel directional spread characteristics for northerly paths

The northerly ionosphere is a dynamic propagation medium that causes HF signals reflected from this region to exhibit delay spreads and Doppler shifts and spreads that significantly exceed those observed over midlatitude paths. Since the ionosphere is not perfectly horizontally stratified, the signa...

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Bibliographic Details
Published in:Radio Science
Main Authors: Warrington, E. Michael, Stocker, A. J., Siddle, D. R.
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union (AGU) 2007
Subjects:
Online Access:http://onlinelibrary.wiley.com/doi/10.1029/2005RS003294/abstract
http://hdl.handle.net/2381/2008
https://doi.org/10.1029/2005RS003294
Description
Summary:The northerly ionosphere is a dynamic propagation medium that causes HF signals reflected from this region to exhibit delay spreads and Doppler shifts and spreads that significantly exceed those observed over midlatitude paths. Since the ionosphere is not perfectly horizontally stratified, the signals associated with each propagation mode may arrive at the receiver over a range of angles in both azimuth and elevation. Such large directional spreads may have a severe impact on radio systems employing multielement antenna arrays and associated signal-processing techniques since the signal environment does not comprise a small number of specular components as often assumed by the processing algorithms. In order to better understand the directional characteristics of HF signals reflected from the northerly ionosphere, prolonged measurements have recently been made over two paths: (1) from Svalbard to Kiruna, Sweden, and (2) from Kirkenes, Norway, to Kiruna. An analysis of these data is presented in this paper. The directional characteristics are summarized, and consideration is given to modeling the propagation effects in the form of a channel simulator suitable for the testing of new equipment and processing algorithms.