Dielectric has taken part in its share of RF installations at iconic transmission sites, from atop Mount Wilson in Los Angeles to One World Trade Center in New York City. The latter is of course also home to the Empire State Building, which today hosts 18 FM and five TV stations on its multi-station master antenna system.
Dielectric has been building out its product line to serve the changing needs and unique challenges of master antenna systems. That includes the early 2023 introduction of a new modular, reconfigurable manifold combiners that allow RF engineers to add new broadcast tenants without the intensive assembly labor required for expanding constant impedance filter (CIF) units, and without affecting RF or electrical performance of adjacent stations in the same systems.
While manifold combiners were not part of the Empire State Building project, Dielectric recently installed an antenna system to support transmission for WEDW-DT, part of the Connecticut Public Television (CPTV) PBS member network that now has improved reach into the coveted New York City television market. It’s a project that included its own unique challenges from initial design through final corrections and commissioning, and now has WEDW radiating through a much broader population.
Joining a Community Site
It’s hard to overstate the logistical challenges of transporting large television antennas to the sky-high installation points on buildings such as the Empire State Building. The main challenge for this project was building a system in sections that met height and weight restrictions for the building’s freight elevators. Height limitations top at 10 feet, which required us to create four antenna sections that could be joined together in the transmission headend between the 80th and 85th floor.
We worked closely with the customer to specify the proper antenna system and directional pattern for their coverage needs. WEDW is licensed to Stamford, CT, situated about 41 miles northeast of New York City. Operating on UHF Channel 21, the station also transmits from an antenna in the Bridgeport region that reaches well into northwest Connecticut and southeasterly into the Hartford region, east of New Haven and into eastern Long Island.
The Empire State Building opening allowed WEDW to expand its signal into New York City, western Long Island, and parts of New York State’s Hudson Valley and northern New Jersey. The process began using our Dielectric Antenna System Planning (DASP) software to generate a design proposal for WEDW’s contour. The DASP interface guides customers through the design process, allowing broadcasters and consultants to base designs on ERP or TPO, import FCC filing information, match design options to technical parameters including polarization, elevation and azimuth patterns.
WEDW required an elliptically polarized antenna with directional horizontal (210 kW ERP) and vertical (84 kW) azimuth patterns to fill in the contour. A TFU Series EST high-power antenna was installed at 1500 feet to serve the station’s 18.4 kW TPO. TFU Series EST antennas are end-fed designs that typically work well with directional azimuth patterns. This is because the outer pipe and inner conductor are both small, and that makes end feeding the most reliable method for sending electrical power into the antenna.
Final Approach
The antenna was quickly reconstructed and lifted into its new side-mount position about 18-20 inches off the face of the tower. Two elbows were added to adjust the antenna position’s based on a final correction. Those adjustments made it easier to connect into existing transmission line sent back down through the tower to interface to the facility’s combining system. At 700 pounds, the antenna’s weight and wind load was built to the structural engineers’ specifications to meet Empire State Building requirements, and in fact came in smaller than the originally approved footprint.
Dielectric’s expertise in high-power broadcasting is well-known in the United States, with more than 80 percent of the high-power TV market share. With projects such as the WEDW antenna design and our new manifold combiners, Dielectric continues to gain valuable experience in the navigating the nuances of master antenna systems across logistics, design attributes and electrical considerations that affect performance of each filter and antenna in the combined RF chain. Be sure to visit dielectric.com for more information on our master antenna system solutions and design proposal software to learn more.
