What kind of SMA connector do you have? For best performance, SMA connector should be intentionally made for RG-174 cable type. If you'll use any other SMA connector and try to connect to a RG-174 cable, you'll get bad performance (high insertion loss, high return loss).
What's the frequency range in interest? RG-174 and SMA is somewhat bad choise, since SMA is high frequency connector and RG-174 high-loss cable, not appropriate for frequencies higher than 1 Ghz... do you need it for WiFi at 2.4 GHz?