The base game's Orbital Antenna and Orbital Radio are not used in Project-X; and are hidden.

The "Signal Relay" research in the "Other" Tech column is what PXR uses.
It unlocks the "Signal Relay" building in the "Science" Building category.,
It is expensive, and the animal wildlife hates it; but it gets you full access to the "Official Trading"
research column on the far right of the tab.

Thanks for info :) but I asked because after building the relay, information appears that at least two antennas are required for proper operation.