47 CFR 17.2 - Definitions.
(a) Antenna structure. The term antenna structure means a structure that is constructed or used to transmit radio energy, or that is constructed or used for the primary purpose of supporting antennas to transmit and/or receive radio energy, and any antennas and other appurtenances mounted thereon, from the time construction of the supporting structure begins until such time as the supporting structure is dismantled.
(b) Antenna farm area. A geographical location, with established boundaries, designated by the Federal Communications Commission, in which antenna structures with a common impact on aviation may be grouped.
(c) Antenna structure owner. For the purposes of this part, an antenna structure owner is the individual or entity vested with ownership, equitable ownership, dominion, or title to the antenna structure that is constructed or used to transmit radio energy, or the underlying antenna structure that supports or is intended to support antennas and other appurtenances. Notwithstanding any agreements made between the owner and any entity designated by the owner to maintain the antenna structure, the owner is ultimately responsible for compliance with the requirements of this part.
(d) Antenna structure registration number. A unique number, issued by the Commission during the registration process, which identifies an antenna structure. Once obtained, this number must be used in all filings related to this structure.