Smith Chart Exercise
Ray Kwok
1) Using Smith Chart only, evaluate the input impedance Zin at 500 MHz as shown in Figure. ZL=50-j25Ω.
C=5pF
ZC=25Ω
ZO=50Ω
L=15nH
ZL
length=0.15λ
Zin
2) Clearly show a matching network for the load ZL = 40 – j10 Ω to a 50 Ω system at 1 GHz,
a) using ANY transmission lines,
b) using a lumped constant circuit element (L or C) AND a shunt transmission line.
c) using ONLY a single transmission line to match it at a single frequency. Calculate the impedance and
line length of that transmission line. If this is not possible, state the reasons.
d) What is the VSWR on the transmission line in (c), if possible?
3) Using Smith Chart only, evaluate the input impedance and reflection coefficient at 300 MHz given that
ZL = 50 + j 150 Ω.
Length = λ / 8
Zo = 100 Ω
L=16 nH
ZO = 50 Ω
ZO = 50 Ω
C = 5.3 pF
R = 167 Ω
ZL
Length = 0.34λ
Zin
Γin
4) Clearly show a matching network for a load of Z=25-j50 Ω to a 50 Ω system at 300 MHz (a) using only
lumped elements, (b) using only open-stubs, (c) using a transmission line (any kind) and a quarter-wave
transformer. Make sure all circuit elements and schematic are clearly defined.
5) Evaluate the value of reactance X and length L, such that Zin would come out to be 50 ohms.
jX
ZC=25Ω
ZO=50Ω
ZL=30-j50Ω
Length L
Zin=50Ω