Steady State Waves

Reflection Coefficient

The reflection coefficient ΓL in a transmission line is given by,

ΓL=ZLZ0ZL+Z0=ρejψρ=(RLZ0)2+XL2(RL+Z0)2+XL2ψ=arctan(XLRLZ0)arctan(XLRL+Z0)

where Z0 is the characteristic impedance and ZL=RL+jXL is the load impedance.

Input Impedance

The input impedance Z(z) at any point along a transmission line is given by,

Z(z)=Z0ZLjZ0tan(βz)Z0jZLtan(βz)β=2πλ

where z is the negative distance from the load and λ is the wavelength.

Voltage Standing Wave Ratio

The voltage standing wave ratio S is given by,

S=1+ρ1ρ