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Tower Move Hurts Signal

myinky.com, the on-line edition of the Evansville (Indiana) Courier and Press newspaper, reported that the signal from WNIN, PBS Channel 9, has suffered since it moved to a new tower site south of Boonville, Ind. The Courier and Press article by Maureen Hayden, WNIN signal improvement flops, said, "Station officials blame the problem on a 'split beam' broadcast signal from a faulty antenna and subsequent attempts to rectify it." Refer to the article for more details on the extent of the signal problem. The article said Dielectric Communications built the antenna.

A quick check of the FCC CDBS showed that while the new site is further from Evansville than the original site, the antenna height above average terrain (HAAT) is significantly higher at the new site--301 meters compared to 170 meters. Both facilities operated at maximum power (316 kW) with an omni-directional antenna pattern. I ran a Longley-Rice analysis and found 77 dBu (city grade) coverage should have been 120 percent that of the old station.

What is strange is that the article said the educational FM station associated with WNIN also was experiencing coverage problems, which, if true, would tend to put the problem with the location rather than the antenna, assuming a different antenna was used for the FM station. My study showed the new site put about 3 dB less signal in Evansville, but this is not a significant difference. Populated areas between Evansville and the old tower site, however, were predicted to see a greater drop. Chandler, for example, was predicted to loss about 7 dB, However, both cases the predicted signal levels were at least 20 dB (97 dBu) above FCC City Grade, so good reception should not have been a problem.

The article reported that Sally Rich, speaking for Dielectric, said she was not aware of the details but that the company wanted happy customers.