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EDN Writer Tries Off-Air DTV – Part Two

Electric Design News (EDN) senior technical editor Brian Dipert continued his tale of off-air TV reception in postings last Friday and this Thursday. Last week Jack Antonio, chief engineer at Reno, Nev. Station KTVN, along with his assistant, Eric Brown, visited Dipert, who was having trouble receiving the station, even though he was able to receive other stations on Slide Mountain, outside Reno.

It turned out the cable in his house was attenuating the high VHF DTV signals by 8 dB. After reviewing the specifications, the engineers confirmed that the Clearstream 2 antenna from Antennas Direct was a UHF-only antenna. Dipert asked Antennas Direct Founder and President Richard Schneider to explain the company’s claim of “consistent gain” through the entire DTV channel spectrum. Schneider responded that designing an antenna that would cover both bands without compromising UHF reception turned out to be harder than expected. The solution they came up with was to redesign the antenna balun to allow the feed line to act as a high-band VHF antenna. The ClearStream 5, a high-band VHF only antenna, is recommended for viewers in fringe areas with high-band VHF reception problems.

In my RF Technology column in the Sept. 3 issue of TV Technology magazine, I’ll look at spectrum usage after Feb. 17, 2009. One quarter of all U.S. TV stations will then be using VHF channels.

See Brian Dipert’s Thin-Air ATSC (And NTSC): An Engineer Visit and An Antenna Reposit for the full story. Also see Thin-Air ATSC (And NTSC): The De-Boost (or Over-Boost) Debacle describing Dipert’s experiences with TV preamplifiers.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.