NILES, IL, September 8, 2010 — Long before the FCC’s order to vacate the 700 MHz band became reality on June 12, WBBM TV-2 Chicago, a CBS owned-and-operated station, was deep into preparations. With IFB (interruptible foldback) and wireless microphone systems affected by the change, the station engaged TC Furlong Inc., a full service pro audio firm in suburban Lake Forest, to evaluate the situation and recommend a solution.
The challenge was to expand the station’s wireless capabilities beyond Studio A, the station’s street-level broadcast center, to include the third-floor newsroom and Daley Plaza, located just outside the studio in downtown Chicago. The newsroom is a large, L-shaped office area where all the anchors, news directors, and dispatch people work. The station uses live newsroom shots for segment previews and breaking news reports. Previously, those shots did not include audio.
“Beyond the 700 MHz issue, the station’s desire was to create a full intercommunications system, so the talent could be called over IFB and respond on their lavalier mic,” explains Jeff Cech, general manager at TC Furlong. “To do that, we needed a unified antenna distribution system that would cover both wireless mics and IFB across all these spaces.”
The specification was for 12 RF mics and eight IFB channels. To handle the microphone system, TC Furlong recommended Shure’s premium UHF-R® wireless line. “We prepared a frequency coordination and saw Shure’s G1 band had plenty of available frequencies, even in downtown Chicago,” recalls Scott Helmke, project manager for TC Furlong. “In fact, they even have a couple spare frequencies available in case the landscape changes.” Choosing Shure also gave WBBM the ability to exchange its legacy 700 MHz systems for significant cost savings.
Working with renowned wireless guru James Stoffo, RF coordinator for the Super Bowl and other major events, the TC Furlong team created a unified system based around a mix of antenna splitters and combiners, paired with various antennas. “The tricky part was, they couldn’t have separate transmitter or receiver systems in the two main rooms, because the talent actually moves between those spaces,” says Jeff Cech. “Based on the frequencies involved and the configurations of the rooms, James Stoffo recommended a mixture of different antenna types and locations that resulted in a single, cohesive system.”
The antenna systems are run through splitters, providing A/B diversity feeds from Studio A and the third-floor newsroom, which are then routed to the Shure UHF-R wireless mic systems, racked together in Studio A, and a similar multiple antenna system for the IFB transmitters, located in a second floor equipment room. This necessitated cable runs of up to 300 feet, accommodated by using LMR600 low-loss, solid core cable in combination with in-line signal amplifiers.
The six dual-channel Shure UR4D receivers accept their signals from two UA845SWB (super wideband) antenna splitters, while the IFB system uses a Shure PA821SWB 8-to-1 combiner and a Model 5624 splitter from Professional Wireless Systems. The two systems are fed by five Shure HA8089 helical antennas, augmented by a circularly polarized antenna, each with a hi-pass/low-pass filter set in-line. To ensure proper signal level, two Shure UA830WB in-line antenna amplifiers add a 3dB boost en route to the splitters.
To get wireless reception from the third floor down to Studio A, two impedance-matching passive antenna splitters combine the antennas from the first and third floors before the signal reaches the receiver. “We could only get away with that because the two spaces are physically isolated from each other,” explains Helmke. “Any transmitter being picked up by in one space is so greatly attenuated in the other area that there’s no real conflict.”
Thus, each space used two antennas (for A and B diversity pickup), all of which are in constant use, creating full and constant communication throughout Studio A and the newsroom. “The only place we lose signal is when the talent gets in the elevator between floors,” explains Cech. “As soon as you walk out of the elevator, the antenna system picks you up again.”
The last piece of the puzzle was to get coverage in Daley Plaza, visible out the windows of Studio A and the third floor area. WBBM needed IFB coverage only outdoors. The solution was to aim one of the Shure HA8089 helical antennas out the third-floor window, which provided coverage for the entire plaza without compromising newsroom pick-up.
“A large part of our success had to do with that Shure UA821SWB combiner, which is actually designed for use with Shure in-ear personal monitoring systems,” he notes. “That product turned out to be uniquely qualified for this application. First, because it’s a wideband system with eight inputs. But more importantly, it could also do power handling for all eight IFB transmitters – which transmit at 250mW. No other product I’m aware of could do the job.”
To make the antenna system as flexible and foolproof as possible, the TC Furlong team designed and fabricated custom antenna mounts, able to handle the weight of the antennas and the heavy cables coming off them while still being flexible enough to be aimed as needed. “Our goal was to get solid coverage in all the main areas, all the time,” explains Scott Helmke. “Since this is live broadcast, we did design some overkill into the system so they can reconfigure the studio at will without re-aiming antennas. Basically, everything they could reasonably foresee can be handled.”
“This was probably the most involved antenna system we’ve ever tackled,” concludes TC Furlong’s Jeff Cech. “It really required some creativity. But with the mix of wireless systems, combiners, splitters, antennas and accessories that Shure offers, we were able to give TV2 Chicago everything they had hoped for. I think it’s fair to say we have a happy customer.”