no signal on my iPhone 5s, antenna problem

Hi there, I'm having problems with my iPhone 5s, basically it got wet and now it doesn't give me signal.

It's not a problem of reading

Sim, so it should be the antenna.

It doesn't say searching, it just says no signal, but when I'm near an antenna I have just one line of network, so very low.

Is it possible changing the antenna and hoping that it will work again?

Or it could be another problem?

If it is the antenna, is it easy chaining it?

As I said before it's not totally broken it works less then usual, when the signal is very strong it gives me one dot, inside building and away from antennas I have no signal.

Cheers