Characteristic admittance

Characteristic admittance is the mathematical inverse of the characteristic impedance. The general expression for the characteristic admittance of a transmission line is:

${\displaystyle Y_{0}={\sqrt {\frac {G+j\omega C}{R+j\omega L}}}}$

where

${\displaystyle R}$ is the resistance per unit length,

${\displaystyle L}$ is the inductance per unit length,

${\displaystyle G}$ is the conductance of the dielectric per unit length,

${\displaystyle C}$ is the capacitance per unit length,

${\displaystyle j}$ is the imaginary unit, and

${\displaystyle \omega }$ is the angular frequency.

The current and voltage phasors on the line are related by the characteristic admittance as:

${\displaystyle {\frac {I^{+}}{V^{+}}}=Y_{0}=-{\frac {I^{-}}{V^{-}}}}$

where the superscripts ${\displaystyle +}$ and ${\displaystyle -}$ represent forward- and backward-traveling waves, respectively.