WiFi antenna loaction (poor signal)

Hi guys!

Recently I had shattered screen in my xperia z3 compact so i bought screen with so called midframe and replaced it. That screen was used but in marvellous condition. Now i have a little problem. Accidently i broke the outer frame (if you know what i mean) in one place. And once i started the phone, the wifi signal was quite poor - on my desk another phone has full wifi signal, but xperia just half. On another forum i've read that there is wifi antenna in frame that i've broken. Is that true? Or the only antenna is that one on the motherboard? That thing happens no matter what OS is installed.