WNIN and ERI Discovered Reason for Poor Coverage from New Antenna
August 25, 2003
Tom Silliman and his firm, Electronics Research Inc. (ERI), appeared to have found the problem with Public Broadcasting Station WNIN's coverage after its tower move. The problem was described in my July 14 RF Report. My calculations showed the move to another site should not have had a significant impact on the received signal in key population areas, certainly not to the extent reported. Myinky.com, the on-line site for the Evansville Courier and Press and the Henderson Gleaner newspapers described the results of Tom Silliman's study in an article by Maureen Hayden, WNIN Ready to clear up static. Her article said Silliman and David Dial, WNIN's chief executive officer, "tromped through farm fields and forests trying to track the signal." The article continues, "What they discovered was that the analog antenna was emitting a 'split beam' broadcast signal." Engineers familiar with TV antenna elevation patterns know the main beam of an antenna can be quite narrow in the elevation plane. Improper phasing between elements in an antenna can cause that beam to miss the area intended or to split into two separate beams, neither hitting the intended area, as appears to be the case here.
According to the article, Dielectric, the manufacturer of the antenna, agreed to take the antenna back and fix it at their expense. The repaired antenna was reinstalled and was scheduled to be tested Friday, August 22nd. As of Sunday night, www.wnin.org did not have any information posted on how the new antenna was performing.