Studies On Wide Area Multi-Hop Network in HF BAND

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We have studied and proposed HF Wide Area Multi-Hop Network in HF Band for emergency situation. It is possible for us to have communication over long distance with low cost in HF Band. It is also possible to have networks without any of infrastructures and Hub station. In this study, we proposed wide area multi-hop network employing HF long distance propagation based upon ionosphere layer reflection. We also proposed some access methods for such systems in terms of shift of transmitting timing and elevation angle control. We have examined the possibilities of elevation angle control using adaptive array system for HF band by some experiments. By using such schemes, we have achieved that our proposed schemes are useful in practical use especially for emergency situations.