What is a Tap Coupler (FBT)?
A tap coupler splits optical power unequally between two output legs: a low-loss pass-through leg (THRU) and a branched extraction leg (TAP). Common ratios include 95/5, 90/10, 80/20, 70/30, 60/40, and 50/50.
Tap couplers are essential in linear route layouts (such as along a main roadway) where you want to drop a small amount of signal at an intermediate junction box while sending the majority of the light further down the line to subsequent nodes.
| Ratio (Thru / Tap) | THRU Leg Loss (dB) | TAP Leg Loss (dB) | Primary Use Case |
|---|---|---|---|
| 90 / 10 | ~ 0.8 dB | ~ 10.5 dB | Near central transmitter (early drop) |
| 80 / 20 | ~ 1.3 dB | ~ 7.4 dB | Intermediate distribution point |
| 70 / 30 | ~ 1.9 dB | ~ 5.7 dB | Mid-route distribution |
| 60 / 40 | ~ 2.6 dB | ~ 4.4 dB | Mid-to-late route |
| 50 / 50 | ~ 3.5 dB | ~ 3.5 dB | End of line balanced split |
When to Use Balanced PLC Splitters
Planar Lightwave Circuit (PLC) splitters divide power evenly across 4, 8, 16, 32, or 64 output ports. They are ideal in star or cluster topologies, such as residential apartment complexes or compact neighborhoods where multiple subscribers reside within close proximity of a single distribution box.
CoreMap allows operators to cascade both FBT tap couplers and PLC splitters seamlessly in its signal editor. When you change a coupler ratio from 80/20 to 70/30, CoreMap instantly recalculates the downstream dBm across every connected subscriber.