Tutorial 3: Planar Transmission Line
Planar Transmission Line:
1.
Design a stripline transmission line for 70Ω characteristic impedance. The
ground plane separation is 0.316 cm, and the dielectric constant of the filling
material is 2.20. What is the guide wavelength on this transmission line if the
frequency is 3.0 GHz?
(Answers:  Z  103.8 < 120;
r
2.
0
g
Design a microstrip transmission line for 100Ω characteristic impedance. The
substrate thickness is 0.158 cm, with Єr = 2.20. What is the guide wavelength
on this transmission line if the frequency is 4.0 GHz?
(Answers: A  2.21 ;
3.
W
 0.467 ; W  0.147cm ;   6.74cm )
b
W
 0.9 ; W  0.142cm ;   1.758 ;   5.656cm )
d
e
g
A 100Ω microstrip line is printed on a substrate thickness 0.0762 cm, with a
dielectric constant of 2.20. Ignoring losses and fringing fields, find the
shortest length of this line that appears at its input as a capacitor of 5 pF at 2.5
GHz. Repeat for an inductance of 5 nH. (Assume copper conductor and tan δ
= 0.001).
(Answers: 0  0.12m ;   3.986.7 / m ;
C  5 pF ;   2.0754cm , Z in   j12.73
L  5nH :   3.2132cm , Z in  j 78.5 )

4.
A microwave antenna feed network operating at 5 GHz requires a 50Ω printed
transmission line that is 16λ long. Possible choices are:
Copper microstrip, with d = 0.16 cm, Єr = 2.20 and tan δ = 0.001, or
Copper stripline, with b = 0.32 cm, Єr = 2.20, t = 0.01 mm and tan δ
= 0.001.
Which line should be used, if the attenuation is to be minimized? The
conductivity loss is   5.813  10 7 S/m.
(1)
(2)
(Answers:
W
 3.09  2 ; W  0.494cm ;   1.87 ;
d
  4.38cm ;   0.061Np / m ;   0.073Np / m ; Loss  0.82dB ;
(a) Microstrip case; B  8.0 ;
g
d
EKT 441: Microwave Communications
e
c
1
Tutorial 3: Planar Transmission Line
W
 0.833 ; W  0.267cm ;
b
  4.045cm ; A  4.73 ;   0.084 ;   0.078 ; Loss  0.91dB )
(b) Stripline case:  Z  74 < 120;
r
0
g
EKT 441: Microwave Communications
c
d
2