Before someone complains about my crappy design I should tell you that my knowledge on antennas or RF is near zero.
I recently worked on a project that required a GSM module. After testing it on a PCB using an external antenna that apparently seamed fairly simple, I made a new PCB with a built in antenna.
It worked well but I noticed that the signal was significantly lower than the one with the external antenna. I also noticed that if I touched the antenna connection with a wire the signal increased in strength close to the one with the external antenna.
My board is a double sided board with a ground plane with a clearance distance of about 2 mm from the antenna on one nearest side. The antenna is located near the edge of the board as can be seen on the picture.
Is there something that I could do to improve my antenna performance? Currently the antenna has solder mask on top of it, can this degrade its performance? Is it better to have it plated instead?