BNC to SMB Cable Assemblies Amphenol RF BNC to SMB Cable Assemblies are available in straight or right-angle BNC plugs to straight or right-angle SMB connectors. The RG-174 and RG-179 cable lengths range from 6' to 3m. Additional features include 50Ω and 75Ω impedance, DC to 1GHz frequency range, and brass contact material with gold plating. Typical applications for Amphenol RF BNC to SMB Cable Assemblies include broadcast and instrumentation.