Abstract:

The comparisons between HF sky wave field strength measurements and predictions made by Report 894- 2 of CCIR have been made. The mean difference and standard deviation are-4. 7dB and 13. 5dB respectively. The reasons of the deviation between measurements and predictions have been analyzed. Also, authors have evaluated the prediction method for path lengths greater than 9000 km involved in Report 894-2 of CCIR and pointed out that the predictions are too low compared with measurements and the antpode focus formula should be modified. If so,the prediction accuracy of Report 894-2 of CCIR will be improved.