You want a combiner not a diplexer. A diplexor is used when you want to add a TV antenna to the same coax as your satellite feed. Diplexers would not work for Hopper installations. A combiner will allow you to take two antennas and bring them to a single coax that you would attach to your OTA adapter. Combiners will work sometimes but can cancel out the signal from both antennas. It wouldn’t hurt to try. Look at Amazon and search for TV Antenna Combiner. They have one for $7.