Study the Impact of the Distance Factor on the Optimal Workable Frequencies for the Long Distance Radio Communications

In this research, the influence of the distance factor on the optimal working frequency (FOT) parameter has been studied theoretically for the ionosphere layer over the Middle East Zone. The datasets of the (FOT) parameter have been generated using the (VOACAP) model which considers as one of the recommended modern international communication models that used to calculate the ionosphere parameters. The calculations have been made for the connection links between the capital Baghdad and many other locations that distributed on different distances and directions over the Middle East region. The years (2011-2013) of the solar cycle 24 have been adopted to study the influence of the distance factor on the FOT parameter. The results of the conducted study showed that the distance factor has a clear influence on the values of the FOT parameter, also the day/night effect is more significant in the long distance HF links (i.e. more than a 500 Km).