| Summary: | 碩士 === 國立中央大學 === 太空科學研究所 === 99 === High-frequency (HF) radio propagation through the ionosphere offers long-distance communication. Theoretically, radio intensity is decreased with increasing path and is affected also in different media. Therefore, it is important to estimate wave-propagation loss for HF communication. We have applied wave intensity equation which combines basic free-space path loss, equipment gain and the ionosphere loss quoted from IONCAP model. Then we compared the estimations with the measurements from the ChungLi dynasonde.
From the comparisons, the results show that the estimations are less than the measurements in daytime but larger after 15:30 local time. Meanwhile, the results show a propagation loss around 90 to 120 dB in vertical sounding above ChungLi. Considering local background noises and distinguishing threshold from system, the ChungLi dynasonde system has to provide more than 50 dBW efficient radio power that radio waves can be successfully measured.
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