c500 reception boost!?

[Guest Xenzo1990]

I recently changed the body fascia of my c500. The cover that goes over the phones internal antenna module is internally coated with some metal, the the fascia did not have this. I just ignored it and put the new one on. However signal was appalling. So I put the old one on, and signal was perfect. Now, i'm wondering exactly what the metal coating does? Can anybody shed any light on it?

[Guest]

acts as an aerial.