Is there conductor on the ribbon wifi antenna for connect with case?

Hi. Recently I replace wifi antenna from my iPad2. During replacement I lost 2 small screws for hold wifi antenna.

So I just use adhesive tape to attach it to body and I finish replacement.

I check my iPad wifi strength with iPhone5 and iPad mini and i found my fixed iPad shows a little bit less wifi strength compare to other devices.

Is this iPad use it's rear panel it self to use as the antenna? Because I saw there is small conductor on the ribbon tiny wifi antenna.

Then I should buy lost screws and re assemble..

Thx in advance.