Evaluation on Correlation between M-curve and Overreach Duct Propagation from Korea to Japen in V-Low Band

It is important to understand the radio environment of the V-Low band in detail, because the FM broadcast waves in V-Low band are important media during disasters. V-Low band are also used as FM broadcasting in Korea, and there is concern about overreaching interference to Japanese broadcasting waves due to duct propagation. A radio duct, which is a main factor of duct propagation, is caused by an inversion layer of atmospheric refractivity. The inversion layer has been modeled by M-curves. The upper air weather required to derive the M-curve is not usually available over the duct propagation path due to the limited number of observation station. In this study, the relationship between the M-curve obtained in propagation and the increase in received level due to duct propagation was evaluated with the aim of estimating duct propagation from the M-curve obtained in upper air not over the propagation path. As a result of the evaluation, the larger the negative slope of the M-curve, the higher the received level, even if upper air was not observed just over the propagation path.