Yeah I built two. You need two to use them. It seemed to work across the galaxy.

However I realized it was more or less redundant. For a fraction of the cost I'd simply build transporters and transport fleets to the area of choice.

Unless it's a way to save resources when a planet gets attacked, any planet with a resource transmitter instantly sends all resources to a friendly planet. The conquered planet starts with zero. This would be an effective tactic for a trader whose massed lots of resources in one sector and sending it to another to be saved.