The detectable double atmospheric ducts for RFC

Refractivity from clutter (RFC) systems are defined for retrieving the atmospheric ducts from the sea clutter echo of a radar in open sea or coastal environment. However, some ducts hardly have an effect on the clutter echo. Consequently, the RFC technique suffers inherent limitations and is unable to provide information about these ducts. To identify these ducts, one important parameter is the range at which a duct modifies the received power. This paper introduces the calculation of this range in the case of a double duct (evaporation and surface-based duct).