iPhone 5S stucks on reaserch after drop

Hello

I droped my iPhone and in the afternoon he begans to lose networks several times until stuck constantly searching for carrier...

I tried all software manipulations to fix it: (hard reset, reset network setteing, using another sim card...etc), when i try restore on itunes i get error 1! I hardly managed to restore it after several tries! the phone get full signal after each restore but only for few secondes / minutes signal is lost and the phone is searching for the carrier again...and stucks on reaerch continually! And there is something curious: the phone never displays (no service) or (no sim card)

I even completely disassembled and reassembled it! Still stucks on reaserch and every thing else works normally.

Please I need advice before bying cellular antenna! because I can't troubleshot this panne!

thank you very much and sorry for my poor english :)