[Q] Antenna drops down sometimes topic

Hi
I'm having this issue since updated my stock rom to 4.4.2 roms. When I set mobile networks to GSM only it works fine but on other options like LTE, after a while antenna drops and nobody can call me!!!
I have tried so many roms and updated my modem couple of times. Now these are specifications:
Rom: Samy delux pick your king 4.2.2
Bootloader version: I9505XXUFNB8
BaseBand version: I9505XXUGNG2
PDA version : I9505XXUGNG4

I took these information from Samsung info app. Please guide me what I have to do to fix this?
thanks