An atmospheric duct consisting of a high-density air layer that starts at high altitudes and continues upward or remains at high altitudes, thus affecting primarily very-high-frequency (VHF) transmission . [ From Weik '89 ]
ELEVATED DUCT
Meaning of ELEVATED DUCT in English
Telecommunication standard terms English vocab. Английский словарь стандартных телекоммуникационных терминов. 2012