Shared grounding block
 

I have DirecTV as well as an OTA antenna. The cable from my Directv dish passes through a cable terminal box on the outside of my house where it is attached to a 4 port ground block before entering the house. I would like the cable from my OTA antenna to pass through the same terminal box before entering the house. Can I attach the OTA to the same (4-port) ground block that the Directv uses or will this cause some sort of interference for the Directv and/or the OTA? Keep in mind that the Directv and OTA are all on separate coaxial cable, I just want them to (hopefully) share the same ground block.

I see no reason not to use the same grounding block for the respective coax cables, assuming the block is properly grounded and that each mast is also properly grounded.

As long as it's a ground block and not a splitter should not be a problem.

You said it's a 4 port, does it have 4 input and 4 output connections?

Yes, it's definitely a ground block....4 in/out ports.

Many splitters (as well as other passive and active distribution devices) also have grounding lugs. Those can be substituted for a dedicated grounding block provided they are properly installed and the rest of the grounding scheme is properly executed.