Single Mode SC / APC Connector

Single Mode SC / APC Connector

Single-mode fiber optic connectors are used to connect and transmit high-frequency signals over long distances with minimal loss. In the Z-Band system, single-mode/simplex SC/APC (Angled Physical Contact) connectors are used exclusively to ensure superior performance by minimizing signal reflections.

In fiber optic communications, connector end face geometry plays a critical role in performance. The two most common types for single-mode fiber are APC and UPC.

SC/APC Connectors

  • Typical return loss: -60 dB or better.
  • Essential for RF video or satellite TV signal transport, where reflection severely impacts signal integrity. 
  • Color coded green to distinguish from other connector types.

Usage Guidelines for Z-Band

  •  Use only single-mode SC/APC connectors
  •  Never mate green APC to blue UPC connectors (causes high signal reflection and potential damage)
  •  Always use properly cleaned, single-mode SC/APC connectors in Z-Band systems. Avoid connector mismatches to maintain signal integrity.
  •  Fiber loss is ~0.5 dB/km (or ~0.000152 dB/foot) — critical in long-distance applications

Losses When Mixing Connectors

  • Mating APC to UPC: ~60% signal reflection; avoid at all costs
  • Dirty connectors: can add several dB of loss and permanently damage fiber face

     Connector Pair

Loss Impact

SC/APC to LC/APC

Minimal loss (~0.2 dB)

SC/UPC to LC/UPC

Minimal loss (~0.3 dB)

X/APC to X/UPC

High loss and reflection (~0.5 dB to >1 dB)

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