In addition to needing to design an antenna array that can withstand strict earthquake codes for KGO-TV and KRON-TV on Sutro Tower, Dielectric needed to take other factors into consideration when designing the new array for the tower repack project.
The stacked antenna array will be affixed to one of the three “candelabra” arms extending from the top of 977-foot tall Sutro Tower. In order to meet the earthquake code, the stacked array is being reinforced with guy wires which are anchored at the top of the candelabra platforms.
Dielectric specializes in tower top and tower stacks but the guy wire requirement is unique to Sutro Tower. The installation grows trickier given the densely-packed downtown residential neighborhood and busy streets surrounding the tower – a job that only a handful of specialized tall tower crews can accommodate, according to the manufacturer.
Each station chose to customize top-mount (slotted coaxial) designs to avoid possible interference between the antennas and the tower that could affect radiated patterns and power levels. Dielectric VP/GM Keith Pelletier notes the design offers what he says is the industry’s lowest windload – yet another critical consideration for this project.
Dielectric will also supply its auxiliary antenna (TLSV series) antenna, as part of a strategy to ensure a clean repack process with no off-air time.
“Since KGO is already operating in the VHF band, we will install an auxiliary antenna lower down on the tower that allows them to operate on channel 7,” Pelletier said. “That frees up the tower top and allows us to install KRON and KGO new antennas on top of the tower and allows KGO to remain on the air. Once that’s completed, KGO can move to its permanent antenna on top and Sutro Tower will remain outfitted with an auxiliary VHF antenna.”
The tower is in Phase 9 of the repack schedule, meaning the wok must be completed by May 2020.
March 13, 2019
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