The Wi-Fi antenna cable is plugged from the logic board to the charger port:
The charger port:
http://www.ebay.com.au/itm/Charger-Port-Flex-Cable-Tools-for-Samsung-Galaxy-S4-Active-GT-i9295-i537-ZVFC714-/181403963740?hash=item2a3c84d15c:g:8gwAAOSwpDdU3HKM
The Wi-Fi antenna cable:
http://www.ebay.com.au/itm/Antenne-Antenna-WiFi-signal-Flex-Kabel-f-Samsung-Galaxy-S4-Active-I9295-i537-K-/361399193724?hash=item542512107c:g:cRcAAOSwN81WC6WL