# Opposite of reflection coefficient

The reflection coefficient (in circuits, for example) is generally given the symbol Gamma ($$\\Gamma\$$). What is the symbol given for the pass or transmission coefficient $$\1-\Gamma\$$?

I've usually just seen it written out in terms of $$\\Gamma\$$ but I'm trying to be more concise in my notation.

• the more obvious notation is to use the scattering matrix subscripts, $s_{21}$ forward output to port 2 – Tony Stewart EE75 Apr 30 at 1:51

\begin{aligned} Reflection\ coefficient&=R,\ \ \Gamma\\\\ Transmission\ coefficient&=Τ,\ \ τ\\\\ Absorption\ coefficient&=K,\ \ \alpha,\ \ \varepsilon,\ \ \mu \end{aligned}
• I'm working with optical couplers which generally already use $\tau$, but 'T' may work as well. – nate Apr 30 at 2:06