Default [Q] Hardware / Antenna / Radio Problems

I've been searching around for a fix to the problems I've had with my Note 2.

Basically I replaced the charging port, as the phone stopped responding to USB input. Everything worked fine but the network signal was suddenly extremely poor, often dropping calls or having no data connection.

I confirmed this was a hardware problem when I inserted a thin piece of wire into the R1 external antenna port on the back of the Note 2. This gave me 2 additional bars, but isn't a great fix as the wire needs to be adjusted frequently.

I was wondering if anyone knows what the problem might be and how to fix it. It seems like it should be a cheap fix, but I'm unsure of what components could be at fault (the new charging port, the antenna cable, a radio?).

As a secondary solution, I'd consider having an external antenna folded inside the back case, but it would need to fit and be cheap. I'm not sure if the connector is the same as the ordinary flex cable (see: http://www.ebay.com.au/itm/141170293...84.m1438.l2649)

Assistance is greatly appreciated. I think I've narrowed the problem down so I'm hoping someone has dealt with all this before.