LAUSR

Abstract The main challenge for high-frequency (HF) sky wave communication is the non-stationary behaviour of ionosphere parameters, which imposes constraints on choosing carrier frequency, signal bandwidth, modulation and receiver algorithms to overcome channel impairments. Short- to medium-range HF communication could be the most likely scenario for a European country due to the terrain and communication infrastructure spreading. The main aim of this work was to evaluate HF channels in Black Sea region for distances up to 600 km. Passive sounding and ray tracing were used in order to estimate attenuation and propagation modes. The measurement campaign lasted 9 months. The results proved that for evaluated channels, more than one propagation modes were recorded at the receiver site. Attenuation depends on frequency and time of the day. The outcomes of this research are useful for HF frequency management and HF waveform design.