2712 Bandpass Filter
Small footprint, up tp 15kW with blowers
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Columbia Metropolitan Convention Center
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Feb 28 – Mar 2
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Interdigital Combining Technology at 4 Times Square
When New York’s premier FM broadcast facility at 4 Times Square expanded to 10 stations in July, it became the first to integrate Shively Labs' new 2640 interdigital balanced combiner technology into an existing resonant cavity system.
The Model 2640 is an ideal choice for the combiner at 4 Times Square, where even the recently expanded facilities are quickly filling. While the FM combiner and Shively Model 6016 broadband panel antenna are designed to handle the RF requirements of a minimum 21 stations, it was anticipated that transmitters for the final FM stations would need to be located on the TV floors.
Shively filter designer Alan Plummer worked closely with Senior Electrical Engineer Peter Matthews and 4 Times Square’s Manager of Communications & Broadcast Operations John Lyons to design a method of locating up to six Model 2640 modules in the space previously allocated to two of the resonant cavity modules. This results in a 20% reduction in the overall combiner footprint, allowing the entire FM broadcast facility to be conveniently located on a single floor of the building and free up additional space for future TV expansion. In designing the new combiner racking system, Alan needed not only to accommodate existing building infrastructure, but to maintain the ability of the combiner to be expanded in any frequency order with no physical relocation of the existing modules and only a few hours of downtime.
The 4 Times Square antenna and combiner were the first major broadcast facility designed from inception to accommodate digital radio. The combiner uses back-feeding to transmit digital signals to the feed system of the antenna, a technique pioneered by Shively Labs, BE, and Entercom at Entercom’s Cougar Mountain facility in 2002, shortly before the start of planning for 4 Times Square. Digital implementation can be accomplished either by using a combined analog/digital transmitter or by simply adding a low-power digital transmitter and isolator to the input hybrid of the station’s combiner module.
The Shively Model 6016 panel antenna is designed to combine separate analog and digital feeds into identical azimuth and elevation patterns. The highly efficient design not only has a very low windload, but also the most omni-directional pattern on the market. Special elevation techniques were used to minimize radiation on the roof top. The site is used almost daily as construction continues on the broadcast facilities at the Empire State Building. Listener feedback (or lack of it) during extended broadcasts from the 4 Times Square site indicate the azimuth pattern is comparable or superior to the Empire State Building antenna, despite the fact that the 4 Times Square facility is approximately 300 feet lower.
The 4 Times Square building is owned and operated by The Durst Organization. This includes management of the broadcast facility. Durst is a leading New York City developer of environmentally responsible buildings, and 4 Times Square has the distinction of being the first “green” commercial office tower. As such, careful attention is paid to every aspect of equipment design and operation to ensure nothing detracts from the high standards Durst has set for construction and operation of this facility. This careful attention to energy efficiency was apparent in the summer of 2003 when the 4 Times Square building remained completely powered and operating through the great blackout. Broadcast facilities operating from 4 Times Square remained on the air continuously throughout the blackout, providing timely and unplanned evidence that the site meets one of its main goals – that of ensuring that broadcasters can serve the public during times of emergency.
As of July 2005, stations broadcasting from 4 Times Square are:
Since 1963, Shively Labs has been supplying FM broadcast antennas, filters, combiners, and related equipment to worldwide markets. Shively Labs is a leading innovator and supplier to the new HD Digital Radio™ market. Shively Labs is a division of Howell Laboratories, Inc. a Bridgton, ME company celebrating its tenth year of Employee Ownership.
Last updated: 11/10/06