Complex sentence: WBKI's transmitter is located 60 miles south of Downtown Louisville; this is necessary so it can stay close enough to its city of license, Campbellsville, to provide that area city grade coverage.
Split into simpler sentences: WBKI's transmitter is located 60 miles south of Downtown Louisville. This is necessary so it can stay close enough to its city of license, Campbellsville, to provide that area city grade coverage.