The equation below can be used to estimate the split ratio and insertion loss for a typical split port. L split = 10 · log 10 (N) L term = (C · L conn) + (S · L splice) L total = L split + L excess + L term + L other + L margin Margin = P rx − Sensitivity Enter excess loss from the splitter datasheet for your wavelength. Add connector and splice. If we have measured gains in linear units (e. in Watts – W), the loss value in dB is calculated by the formula: Loss (dB) = 10 lg ( mW1 / mW2 ) When both gains are equal, the loss is 0 dB, so there is no loss (doesn't happen obviously). Real beam splitters use multi-layer coatings that modify R/T beyond Fresnel predictions. All information, equations, and.