What does wire matrix on case back do?

My battery expanded and pushed the back case away. When I separated it fully, I found that I broke a connection to a wire matrix or mesh hidden under a black "paper" attached to the case back. I'm having the battery replaced by ubreakifix, but the phone works as is. So, what is the function of the now disconnected wire matrix, and what problems should I expect if it can't be reconnected?