Complex sentence: The notion became obsolete since the completion of the transition from analog to digital television in 2009; the majority of television stations now broadcast on the UHF band because, by contrast, it is generally considered superior for digital transmission.
Split into simpler sentences: The notion became obsolete since the completion of the transition from analog to digital television in 2009. The majority of television stations now broadcast on the UHF band because, by contrast, it is generally considered superior for digital transmission.