MB865 (Atrix 2) Hardware Question/Help Needed

My MB865 (Atrix 2) started losing signal and restarting. When it does re-acquire a signal, it is always a strong signal (5 bars ~ -65-d. The problem has been getting worse and it is getting more difficult to acquire/retain a signal. Often the phone will spontaneously re-start as well. The re-starting seems to happen more frequently when I am charging the phone or do not have a signal.

My son has the exact same phone with the exact same configuration, and his is working perfectly. Side-by-side, he will have 5 bars while I'm not able to get a signal at all.

I have been told that this is likely an antenna issue, but I'm truly not sure.

Could a faulty antenna cause the re-starting issue described above? If it is a faulty antenna, is this something I could replace myself? I was unable to turn up anything useful in my search for a replacement antenna for this phone, so I'm not sure where to even get one.

Thanks in advance.