If I were to recommend a New antenna , I would recommend a Antenna Craft HD850 All channel antenna installed above the Peak Of The Roof in such a manner that the roof and house are not impeding and blocking reception in the direction of , South/South East.
Aim the HD850 antenna at about 160 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
Connect a NEW Continues Length Of Coax to the New HD850 antenna.
Run the NEW Continues Length Of Coax through a open door or window direct to and connect to 1 Tv.
Scan for the Digital Broadcast Tv stations/channels.
Having received the - Many - Digital Broadcast Tv stations/channels.
You now have antenna and coax that can be used as a Test signal.
Disconnect the NEW coax from the Tv and use the New continues length of coax to test coaxes that are in/on the house.
A New coax is connected to the Tv and connected to coaxes in/on the house.
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Also the coax that is in/on the house can be -->bypassed not used.
Run a New length of coax from the antenna , on the outside wall of the house , go through the wall of the house with the coax , to the Tv.
Or run the New coax from the HD850 antenna some other way to get to the Tv.