The signal strength of WPXA-DT Real UHF channel 51 is Very Low Signal Strength at , minus -4.8 NM(dB) and has 2 Path obstruction and is 47.8 miles away.
Will most likely not be received with any type or kind or size of antenna in the attic.
Recommend install a Winegard HD9095P UHF antenna above the roof so the roof and building are not obstructing reception in the direction of WPXA.
Try a Winegard CC7870 , Isolation Transformer Type Combiner to combine the HD9095P UHF antenna and Y10-7-13 VHF antenna.
Isolation transformer type combiners , the inputs and output are decoupled with transformers , this reduces antenna cross talk and signal strength bleed off of one antenna to the other antenna.
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Another way to do it is use a Remote Control A/B antenna switch with seperate coax runs to the Tv locations.
http://www.mcmelectronics.com. Part number , 34-4425 .
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http://www.solidsignal.com.
http://www.amazon.com.
http://www.winegarddirect.com.