Tropospheric over-the-horizon (OTH) propagation is an important research topic in radar countermeasures and reconnaissance. Clarifying how it affects radar emitter signatures provides an important basis for over-the-horizon radar emitter recognition (RER) in complex electromagnetic environments. In recent years, both the theoretical understanding and practical applications of tropospheric OTH propagation mechanisms and RER have continued to develop. However, the integration of these two areas remains limited, and a focused synthesis of the reported effects of OTH propagation on radar emitter signatures and their related mechanisms is still lacking. On this basis, this paper reviews the mechanisms and models of tropospheric OTH propagation, analyzes emitter signal characteristics from the perspective of propagation-channel characteristics, and summarizes the research progress in this field. Finally, this paper discusses the main challenges and possible improvement directions for RER in OTH scenarios, providing a reference for further research on the integration of OTH propagation and RER technologies.
Liu et al. (Wed,) studied this question.