WUCW-DT, licensed to the Minneapolis-St. Paul market, is now on-air with a new Dielectric UHF antenna. Dielectric says the new antenna reevaluates traditional stacked antenna array design and brings simplicity and long-term reliability to the broadcaster.
The E-Type antenna design addresses current tower code requirements for exposed transmission lines. It was delivered in a modular configuration that simplified the antenna replacement project for Tower King II, which managed all site preparation and installation work. The engineered system also retained the existing Dielectric repack antenna on the top position without requiring extensive tower modifications.
WUCW shares space with several broadcasters on the south tower at Telefarm Towers, a two-tower transmission site for TV and FM radio broadcasters. To optimize tower real estate and provide true omnidirectional performance for their viewers, WUCW and KSTP-DT have long transmitted from a top-mounted broadband stacked antenna system.
One of many challenges was how to run the transmission line to the top KSTP antenna. Previous revisions of design codes allowed Dielectric to run the line up the side of an antenna mast, exposed to the elements without increasing the mast drag coefficient. “The latest code revisions required by Telefarm impose mast designs with exposed appurtenances such as transmission line with higher drag coefficients, which greatly increase wind loads,” said James Butts, Mechanical Engineer, Dielectric. “We had to come up with an antenna feed system design that would obscure the transmission line without increasing the wind load on the bottom antenna. That meant routing the feed to the top KSTP antenna under the radome of the bottom WUCW antenna.”
Dielectric designed a two-piece mast for WUCW that measures 20 inches in diameter and is two inches thick. To make Tower King II’s job easier, Dielectric split the new bottom antenna into two pieces, adding a flange in the middle. That allowed the tower crew to raise the antenna and split the lifting load on the tower and gin pole as the total antenna weight was close to 30,000 pounds, and later connect the two pieces using the carefully positioned flange.
“The biggest challenge mechanically was to keep the weight of those two sections low enough for a potential helicopter lift or a reasonably sized gin pole,” said Butts.
“The original Deltastar antenna was 32,000 pounds with a very tight guide path, and that made it very challenging to bring the antenna down with a gin pole without it bouncing off the tower,” said Kevin Barber, Owner and President of Tower King II. “That basically requires walking the entire antenna down the tower, which is fairly difficult. We inserted a stabilizing frame between the two antennas, and then jumped the gin pole down to secure the Deltastar and begin the process of walking it down.”
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