Determine the stub length lB required to produce the reactance/susceptance to move the rotated impedance/admittance to the origin.Įxample: Design a double-stub shunt tuner to match a load impedance ZL = 60 – j80 Ω to a 50 Ω line. Rotate the modified load impedance/ admittance onto the g=1 circle 7. Determine the stub length lA required to produce the reactance/susceptance in part 4. Translate yL along a resistance/ conductance circle to get onto the rotated g=1 circle ECE357 / Prof. Rotate this circle d0/λ wavelengths towards the load (CCW) this is the circle on which yA should be located. Draw the g=1 circle this is where yB should be located. lA, lB used to tune the network ECE357 / Prof.Be very careful of: – If you need to work on an impedance or an admittance chart – Where the open/short circuit locations are on each chart ECE357 / Prof.Shorter line sections and stubs give better performance in terms of bandwidth – Shorter transmissions lines have less variation of electrical parameters with frequency.
HumĮxample: Match a load impedance ZL = 100 + j80 Ω to a 50 Ω line using a single series open-circuit stub.Įxample: For a load impedance ZL = 15 + j10 Ω, design two tuning networks based on shunt short-circuited stubs to match this load to 50 Ω. Determine stub length ℓ between the open / short circuit point and the points representing ±jx’ (±jb’) ECE357 / Prof. Determine load-section length d from angles between point representing zL (yL)and the point on the rL=1 (gL=1) circle 4. Draw the |Γ| circle and translate the impedance along the line to the rL=1 (gL=1) circle (2 solutions) => r’ = 1±jx’ (y’ = 1±jb’) 3. Plot the normalized load impedance on the Smith Chart (and convert to admittance for shunt stub tuning) 2. Single-Stub Matching: Steps (shunt version in parentheses) 1. The parameters of the line are as follows: Z0 = 75 Ω, α = 0.029 Np/m, and β = 0.2π rad/m. Input Impedance / Input Reflection Coefficient from a Lossless LineĮxample: What is the input impedance seen into a 0.2λ line terminated in ZL?Įxample: Determine the input impedance of a 2 m long line terminated in a load impedance ZL = 67.5 – j45 Ω. The Smith chart consists of a plot of the normalized impedance or admittance with the angle and magnitude of a generalized complex reflection coefficient in. Intersection of rLcircle and xLcircle defines a normalized load impedance.rL- and xL- circles are orthogonal to each other.