Meteoric ionization : The interpretation of radar trail echoes

An overview is presented of the developments during the key stages in the recognition of the mechanisms governing the behavior of meteoric ionization and an understanding of the radio-reflection processes. Meteors were the source that provided the enigmatic echoes: the fleeting radio returns seen in early ionospheric soundings, or as interference on communication links. The paper covers the key observations, probing techniques, and theoretical developments that enabled progress to be achieved in our understanding of the scattering processes from meteoric plasma, for the case of a reflection geometry giving rise to trail echoes. The development of meteor-echo theory enabled the realization of the value of radar meteors as valuable atmospheric and astronomical probes.