HF Sky wave hop-propagation on earth’s surfaces in different conditions

Abstract

HF Radio waves can be reflected by the ionosphere and the earth’s surface and propagate long distance from the transmitter to the receiver with several hops, which is also called sky wave propagation. Path loss of sky wave propagation varies with different conditions of ionosphere and types of the earth’s surfaces. In order to get a deeper insight into the multi-hop sky wave propagation, we establish a model to investigate calculate the propagation losses under certain circumstances. We separate the path loss into three parts, namely the free space propagation loss (FSPL), the ionosphere propagation loss (IPL) and the sea surface reflection loss (SSRL). The FSPL and the IPL are calculated by using the propagation loss equations from ITU (International Telecommunication Union) standard. The SSRL is estimated by Pierson-Moscowitz (PM) sea wave spectrum and Kirchhoff approximation (KA) method. The model results agree well with the existing observations that the strength of the reflection off the turbulent ocean attenuates more than that of the clam ocean.