ADAMSON UNIVERSITY

COLLEGE OF ENGINEERING

ECE DEPARTMENT

TRANSMISSION LINE REVIEWER-

MULTIPLE CHOICE

REFERENCE: Review Book (2009) by

Cuervo Santos

Communication System by

Blake

Submitted By:

Caldejon Ashley Q.

Calamucha, Xiareen Taye C.

Casantusan, Genielyn

Bernadeth B. Zari, PECE

Instructor 
TRANSMISSION LINE a. Propagation Velocity
 b. Stub
Identification:
c. Smith Chart
1. A device for coupling balanced and d. Surge Impedance
unbalanced lines.
Answer: A
a. Balun
 b. Transmission Line 6. A section of transmissi
t ransmission
on line,
c. Coaxial Line electrically a quarter-wavelength in
d. Open-wire Line length, that is used to change
impedances on a transmission line.
Answer: A
a. Propagation Velocity
2. The ratio between voltage and  b. Quarter-wave transformer 
current on an infinitely long c. Stub
transmission
transmission line. d. Smith Chart
a. Balun
Answer: B
 b. Characteristic Impedance
c. Propagation Velocity 7. The ratio of reflected to incident
d. Reflection Coefficient voltage on a transmission line.
a. Smith Chart
Answer: B
 b. Standing-wave Ratio
3. A transmission line containing c. Reflection Coefficient
concentric conductors. d. Velocity Factor 
a. Transmission Line
Answer: C
 b. Quarter-wave Transformer 
c. Coaxial Line 8. A graphical transmission line
d. Stub calculator.
a. Stub
Answer: C
 b. Velocity Factor 
4. A transmission line containing c. Reflection coeffi
coe fficient
cient
 parallel conductors separated by d. Smith Chart
spacers.
Answer: D
a. Balun
 b. Transmission Line 9. The ratio of maximum to minimum
c. Coaxial Line voltage on a transmission line.
d. Open-wire Line a. Stub
 b. Balun
Answer: D
c. Velocity Factor 
5. The speed at which signals travel d. Surge Impedance
down a transmissi
t ransmission
on line.
Answer: A
10. Any pair of conductors used to  b. Optical fibers
conduct electrical energy. c. Stub
a. Stub d. Balun
 b. Transmission Line
Answer: B
c. Balun
d. Coaxial Line 15. Emitted then radiated through air or 
a vacuum or sometimes water.
Answer: B
a. Balun
11. Ratio of the speed of propagation on  b. Stub
a line to that of light in free space. c. Unguided signals
a. Balun d. Guided signals
 b. Coaxial Line
Answer: C
c. Velocity Factor 
d. Reflection Coefficient 16. Transmission media that are wireless
systems (i.e., those without a
Answer: C
 physical conductor)
12. Transmission media with some form a. Guided transmission media
of conductor that provides a conduit  b. Copper wires
in which electromagnetic signals are c. Optical fibers
contained. d. Unguided transmission media
a. Transmission line input
Answer: D
impedance
 b. Reflection Coefficient 17. A guided transmission medium and
c. Unguided transmission media can be any physical facility used to
d. Guided transmission media  propagate electromagnetic signals
 between two locations in a
Answer: D
communications system.
13. Transport signals using electrical a. Cable transmission medium
current.  b. Guided transmission medium
a. Copper wires c. Unguided transmission medium
 b. Optical fibers d. Optical transmission medium
c. Stub
Answer: A
d. Balun
18. The most common means of 
Answer: A
interconnecting devices in local area
14. Transport signals by propagating networks because cable transmission
electromagnetic waves through a systems are the only transmission
nonconductive material. medium suitable for the transmission
a. Copper wires of digital signals.
 a. Cable transmission medium d. Stub
 b. Cable transmission systems
Answer: B
c. Transmission Line
d. Balun 23. Comprised of two or more metallic
conductors.
Answer: B
a. Series-wire transmission lines
19. A metallic conductor system used to  b. Open-wire transmission lines
transfer electrical energy from one c. Parallel-wire transmission lines
 point to another using electrical d. Closed-wire transmission lines
current flow.
Answer: C
a. Copper wire
 b. Optical fiber  24. Nonconductive insulating material.
c. Transmission Line a. Metal
d. Cable  b. Twin lead
c. Silver 
Answer: C
d. Dielectric
20. Type of transmission where one
Answer: D
conductor carries the signal, and the
other conductor is the return path. 25. Consist of two parallel wires, closely
a. Unbalanced transmission lines spaced and separated by air.
 b. Regular transmission lines a. Open-wire transmission lines
c. Irregular transmission lines  b. Closed-wire transmission lines
d. Balanced signal transmission c. Series-wire transmission lines
d. Parallel-wire transmission lines
Answer: D

Answer: A
21. Type of transmission where one wire
is at ground potential, whereas the 26. Essentially the same with open-wire
other wire is at signal potential. transmission line except that the
a. Unbalanced signal transmission spacers between the two conductors
 b. Balanced signal transmission are replaced with a continuous solid
c. Regular signal transmission dielectric that ensures uniform
d. Irregular signal transmission spacing along the entire cable.
a. Open-wire transmission lines
Answer: A
 b. Twin lead
22. Most common type of balun is c. Closed-wire transmission lines
 __________. d. Parallel-wire transmission lines
a. Cable balun
Answer: B
 b.  Narrowband balun
c. Shield
27. Formed by twisting two insulated Answer: B
conductors around each other and
31.Often used for high data
often stranded in units, and the units
transmission rates to reduce losses
are then cabled into cores containing
and isolate transmission paths.
up to 3000 pairs of wire.
a. Plenum
a. Open-wire transmission lines
 b. Stub
 b. Parallel-wire transmission lines
c. Coaxial cables
c. Twisted-pair transmission lines
d. Optical fibers
d. Twin lead
Answer: C
Answer: C

32.A coaxial cable with one layer of foil

28. Consists of two copper wires where
insulation and one layer of braided
each wire is separately encapsulated
shielding is referred to as ____ 
in PVC insulation.
shielded.
a. Shielded wire
a. Single
 b. Shielded twisted pair 
 b. Triple
c. Stranded wire
d. Unshielded twisted pair cable c. Quadruple
d. Dual
Answer: D
Answer: D
29. A parallel two-wire transmission line
33.Consists of two layers of foil
consisting of two copper conductors
insulation and two layers of braided
separated by a solid dielectric
metal shielding.
material.
a. Quad shielding
a. Shielded-twisted pair cable
 b. Dual shielding
 b. Unshielded-twisted pair cable
c. Single shielding
c. Shielded wire
d. Triple shielding
d. Stranded wire
Answer: A
Answer: A

34.Relatively expensive to manufacture,

30. The name given to the area between
and to minimize losses, the air 
the ceiling and the roof in a single-
insulator must be relatively free of 
story-building or between the ceiling
moisture.
and the floor of the next higher level
a. Water-filled coaxial cables
in a multistory building.
 b. Rigid air-filled coaxial cables
a. Stub
c. Optical fibers
 b. Plenum
d. Shielded wires
c. Wire
d. Platinum Answer: B
35.Used to express the attenuation and d. Shielded wire
the phase shift per unit length of a
Answer: C
transmission line.
a. Reflection coefficient 40.The ratio of the ac resistance to the
 b. Velocity constant dc resistance of a conductor is called
c. Propagation constant  __________ ratio.
d. Velocity factor  a. Capacitor 
 b. Diode
Answer: C
c. LED
36.Other name for propagation constant. d. Resistance
a. Reflection coefficient
Answer: D
 b. Velocity constant
c. Velocity factor  41.Also directly proportional to
d. Propagation coefficient frequency.
a. Radiation loss
Answer: D
 b. Radiance loss
37.Defined as the ratio of the actual c. Copper loss
velocity of propagation of an d. Capacitor loss
electromagnetic wave through a
Answer: A
given medium to the velocity of 
 propagation through a vacuum. 42.Occurs whenever a connection is
a. Velocity factor  made to or form a transmission line
 b. Reflection coefficient or when two sections of transmission
c. Propagation coefficient line are connected together.
d. Stub a. Radiation loss
 b. Coupling loss
Answer: A
c. Capacitor loss
38.Other name for velocity factor  d. Resistance loss
a. Propagation factor 
Answer: B
 b. Velocity constant
c. Propagation value 43.A luminous discharge that occurs
d. Propagation constant  between the two conductors of a
transmission line when the difference
Answer: B
of potential between them exceeds
39.The relative permittivity of a the breakdown voltage of the
material. dielectric insulator.
a. Velocity a. Radiation loss
 b. Acceleration constant  b. Coupling loss
c. Dielectric constant c. Corona
 d. Copper loss 47. TDR stands for:
a. Total Distance of Reflection
Answer: C
 b. Time-Domain Reflectometer 
44.A transmission line with no reflected c. Time-Domain Response
 power. d. Transmission Delay Ratio
a. Coaxial transmission line
 b. Optical transmission line ANS: B
c. Copper transmission line
d.  Nonresonant line 48. An example of an unbalanced line is:
a. a coaxial cable
Answer: D  b. 300-ohm twin-lead TV cable
c. an open-wire-line cable
45.Other name for nonresonant line.
d. all of the above
a. Flat
 b. Round
ANS: A
c. Coupled
d. Single
49. When analyzing a transmission line, its
Answer: A inductance and capacitance are considered
to be:
46.Defined as the ratio of the maximum a. lumped
voltage to the minimum voltage or   b. distributed
the maximum current to the c. equal reactances
minimum current of a standing wave d. ideal elements
on a transmission line.
a. Round-wave ratio ANS: B
 b. Standing-wave ratio
c. Single-wave ratio 50. As frequency increases, the resistance of 
d. Double-wave ratio a wire:
a. increases
Answer: B
 b. decreases
47. SWR stands for: c. stays the same
a. Shorted Wave Radiation d. changes periodically
 b. Sine Wave Response
c. Shorted Wire Region ANS: A
d. none of the above
51. The effect of frequency on the resistance
ANS: D of a wire is called:
a. I 2 R loss
 b. the Ohmic effect
c. the skin effect
 d.there is no such effect d. none of the above

ANS: C ANS: D

51. As frequency increases, the loss in a 56. The velocity factor of a cable depends
cable's dielectric: mostly on:
a. increases a. the wire resistance
 b. decreases  b. the dielectric constant
c. stays the same c. the inductance per foot
d. there is no loss in a dielectric d. all of the above

ANS: A ANS: B

52.The characteristic impedance o f a cable 57. A positive voltage pulse sent down a
depends on: transmission line terminated in a short-
a. the resistance per foot o f the wire circuit:
used a. would reflect as a positive pulse
 b. the resistance per foot and the  b. would reflect as a negative pulse
inductance per foot c. would reflect as a positive pulse followed
c. the resistance per foot and the  by a negative pulse
capacitance per foot d. would not reflect at all
d. the inductance per foot and the
capacitance per foot ANS: B

ANS: D 58. A positive voltage pulse sent down a

transmission line terminated with its
54. For best matching, the load on a cable characteristic impedance:
should be: a. would reflect as a positive pulse
a. lower than  Z 0  b. would reflect as a negative pulse
 b. higher than  Z 0 c. would reflect as a positive pulse followed
c. equal to  Z 0  by a negative pulse
d. 50 ohms d. would not reflect at all

ANS: C ANS: D

55. The characteristic impedance of a cable: 59. A positive voltage-pulse sent down a
a. increases with length transmission line terminated in an open-
 b. increases with frequency circuit:
c. increases with voltage a. would reflect as a positive pulse
 b. would reflect as a negative pulse ANS: C
c. would reflect as a positive pulse followed
 by a negative pulse 64. A Smith Chart is used to calculate:
d. would not reflect at all a. transmission line impedances
 b. propagation velocity
ANS: A c. optimum length of a transmission line
d. transmission line losses
60. The optimum value for SWR is:
a. zero ANS: A
 b. one
c. as large as possible 65. Compared to a 300-ohm line, the loss of 
d. there is no optimum value a 50-ohm cable carrying the same power:
a. would be less
ANS: B  b. would be more
c. would be the same
61. A non-optimum value for SWR will d. cannot be compared
cause:
a. standing waves ANS: B
 b. loss of power to load
c. higher voltage peaks on cable 66. A balanced load can be connected to an
d. all of the above unbalanced cable:
a. directly
ANS: D  b. by using a filter 
c. by using a "balun"
62. VSWR stands for: d. cannot be connected
a. variable SWR 
 b. vacuum SWR  ANS: C
c. voltage SWR 
d. none of the above 67. On a Smith Chart, you "normalize" the
impedance by:
ANS: C a. assuming it to be zero
 b. dividing it by 2p
63. The impedance "looking into" a matched c. multiplying it by 2p
line: d. dividing it by  Z 0
a. is infinite
 b. is zero ANS: D
c. is the characteristic impedance
68. The radius of the circle you draw on a
d. 50 ohms Smith Chart represents:
a. the voltage
 b. the current
c. the impedance
d. none of the above

ANS: D

69. The center of the Smith Chart always

represents:
a. zero
 b. one
c. the characteristic impedance
d. none of the above

ANS: C

70. A TDR is commonly used to:

a. measure the characteristic impedance of a
cable
 b. find the position of a defect in a cable
c. replace a slotted-line
d. all of the above

ANS: B
II. PROBLEM SOLVING a. 14.7 
 b. 14.8
71.A parallel-wire line spaced at 1.27 cm
c. 14.9
has a diameter of 0.21 cm. What is the
d. 15.1
characteristic impedance?

Solution:
a.
 b.
304 
303  Zo=
    

ln ( )
c. 301 
d. 300 
Zo=
    

ln (


)


Zo = 14.7
Solution:

Zo = 276 log
 74. In an improperly loaded transmission
line, determine the power reflected from the
Zo = 276 log
 load if the incident power at the load is 500
W and the reflection coefficient is 0.71.
Zo= 298.8  § 300 
a. 252.05
72.In a coaxial line if the inner diameter is  b. 252.06
0.51 cm and the center conductor has a c. 253.4
diameter of 0.22 cm. What is the d. 254
characteristic impedance?
Solution:
a. 50.1  2
Pref = t Pinc
 b. 50.2  2
Pref = (0.71) (500)
c. 50.4 
Pref = 252.05
d. 50.5 

75. In wire communications

Solution:
Zo= 138 log
 system,calculate the return loss in dB, if the

Zo= 138 log (

 )
load impedance is 600 ohms and the
characteristics impedance of the line is 300
Zo= 50.4  ohms.

73. A stripline is formed using a multilayer  a. 9.60

 board (dielectric constant =2). The center   b. 9.56
track is 0.15 inch wide and 0.005 inch thick  c. 9.54

and the PC board first- layer thickness is d. 9.52

0.05 inch thick., with an overall board
Solution:
thickness of twice the single layer. What is
its characteristic impedance? Return Loss (dB)= 20 log(

 

)
 Return Loss (dB)= 20 log(

 

) Zo= 72.4 

 

 78. Determine the impedance of a balanced
Return Loss (dB)= 20 log( )
  2-wire with unequal diameters d1 = 12 mm
and d2= 10mm. The spacing between wires
Return Loss (dB) = 9.54dB is 30mm.

76. The VSWR on a loss- free line of 50 a. 35.56M

ohm characteristic impedance is 4.2.  b. 35.57M
Determine the value of the purely resistive c. 35.55M
load impedance which is known to be larger  d. 35.58M
than 50 ohms.
Solution:
a. 211
Zo =
  
 
b. 210
c. 209 Zo =
  
 

d. 208 Zo= 35.36 M

Solution: Where,
VSWR =



 N = [ (
)±(
 ) ± ((
 )]
RL = (VSWR)(Zo) 
 N = [ (


 )±(
 )±(
 )]
RL= (4.2)(50)
RL= 210   N= 13.98

77. A microstrip lie is formed using a 0.095 79.For a parallel-wire line, determine the
-
inch thick PC board (dielectric constant = conductance if the conductivity is 200 x10 6
1.8) with a bottom grounds plane and a S/m and the conductor diameter is 12 mm.
single 0.15 inch wide, 0.008 inch thick track  The conductor spacing is 10mm.
on the top. What is its characteristic
impedance? a. 1.56 mS/m
b. 1.23 mS/m

a. 72.8 c. 1.76 mS/m

 b. 72.6 d. 1.89mS/m
c. 72.4
Solution:
d. 72.2
G=

Solution:

Zo=
 
   
ln ( )   

Zo=


  
ln ( )
G=


G= 1.23 mS/m
 2.3 ,an inner conductor of 1 mm diameter 
and an outer conductor of diameter 5 mm?
80. What is the characteristic impedance of  a. 64
an open-line with conductors 4mm in  b.65.9
diameter separated by 15 mm? c. 63.6
d.67.9
a. 241. 52 
 b. 242.66 Solution:
c. 243.62 Zo=
 log

d. 244

Solution:
Zo=

 log

Zo =


log
 Zo= 63.6

Zo =


log
 83.Calculate the velocity factor of a coaxial
cable used as a transmission line, with the
Zo= 241.52 characteristic impedance of 50 ,
capacitance is 40 pF/m and inductance equal
to 50H/m.

81. The Forward power in a transmission

line is 150 W and reverse power is 20 W.
6
Calculate the SWR on the line. a. 22.36 x10 m/s

a. 2.15  b. 23.36 x106 m/s

  b. 4.2.1
c. 24.36 x106 m/s
c. 2.13
d. .2.12 d. 25.36 x106 m/s

Solution:
  Solution:
SWR =
  

Vp = c Vf 
  

SWR =
  

  
 

Vf= =

SWR = 2.15
Vf= 0.0745
82. What is the characteristic impedance o f a
coaxial cable using a so lid polyethylene Where :
dielectric having a relative permeability of 
 Vp=
 

=
  
Vp=22.36x  
m/sa
a.11.10ft

 b. 11.08ft
84. What is the characteristic impedance of a
coaxial cable using solid polyethylene c. 11.07ft
dielectric having a relative permeability of 
2.3, an inner conductor of 1mm diameter  d. 11.05ft
and an outer conductor of diameter 5mm?

Solution:
a. 4.25ft.   
= 
 
 b. 4.26ft.

c. 4.24ft.

d. 4.23ft.
=
  


Solution: = 6.75 m

  
= 
 

Length =

=
  
 = 3.375 m

= 11.07 ft.
 = 5.175m = 16.974 ft

86. What is the actual length in feet of one-


Length =
 quarter wavelength of a coax with a velocity
factor of 0.68 at 30 MHz?
=
  
 

Length = 4.24 ft. a. 5.576 ft

 b. 5.577 ft

85. What is the actual length in feet of one- c. 5.578 ft

half wavelength of a coax with velocity
factor of 0.63 at 28 MHz? d. 5.579 ft
Solution:
=
  

= 6.8 m = 22.33 ft.
  
=  
 

Length = = 11.16ft

=
  

= 6.8m 89. What is the actual length in feet of a one
quarter wavelength of a coax with a velocity
factor of 0.695 at 42 MHz?


Length = = 1.7 m = 5.576 ft
a. 4.05ft

87. What is the actual length in feet of a one  b. 4.06ft

c. 4.07ft
half wavelength of a coax with a velocity
factor of 0.61 at 27 MHz? d. 4.08

Solution:
a. 11.12ft.
  
 b. 11.13ft. = 
 
c. 11.14ft.
d. 11.15ft.
=
 
 


Solution:
   = 4.96 m= 16.28 ft
= 
  
Length = = 4.07ft

=
 
  
90. An amplifier with 20 dB ga in is
= 6.78 m= 22.23 ft connected to another with 10dB gain by


Length = = 11.12 ft. means of a transmission line with a loss of 
4dB if a signal with a power level of -14 dB

88. What is the actual length in feet of a one were applied to the system, calculate the
half wavelength of a coax with a velocity  power output.
factor of 0.59 at 26Mhz?
a.13 dBm
b.12 dBm
a. 11.20ft
 b. 11.19ft c.11 dBm
c. 11.17ft d. 10 dBm
d. 11.16ft
Solution:
Solution: Po(dBm)= Pi(dBm) + GT(dBm) ± LT(dBm)
   Po(dBm)= -14(dBm) + (20+10)(dBm) ± (4)(dBm)
= 
  Po= 12 dBm
 91. An attenuator has a loss of 26 dB. If a
 power of 3W is applied to the attenuator, D
find the output power.

a. 7. 50mW D
 b. 7. 51mW
c. 7.53 mW a. 100
d. 7.54 mW  b. 101
c. 102
d. 103
Solution: Solution:

L(dB)= 10 log
  For d<< D1 D2


 
  
 
Pout = Zo=



  D1=D2 = 2.5 cm
Pout =

   
Pout= 7. 54 mW
Zo=
      


 
Zo= 99.23 
92. What would be the approximate series Zo= 100
impedance of a quarter- wave matching line
used to match a 600 ohms feed to 70 ohms 94. What is the characteristic impedance of a
antenna? single wire with diameter d =0.25 mm
 placed at the center between grounded
a. 204.94  parallel planes separated by 1mm apart? The
 b. 204.95 wire is held by a material with a velocity
c. 204.96 factor of 0.75.
d. 204.97
a. 76 ohms
 b. 77 ohms
Solution:
Zo¶ =
Zo¶ =

 = 204.94
c. 74 ohms
d. 75 ohms

Solution:
93. What is impedance of a ba lance 4-wire
with a diameter of 0.25 cm and spaced 2.5 For 
  
cm apart using an insulator with a dielectric
constant of 2.56?
Zo=
 
 G=

Zo= 
Zo= 75 ohms


 
G=


Where d = 0.25 mm G= 2.76 x 10-9 S/m
h= 1 mm
Where
 = Vf = 0.75  
  


   

95. What is the phase coe fficient of a

transmission line at the frequency of 10MHz 97. What is the input impedance o f a
if the velocity of propagation is 2.5 x 108 transmission line if its characteristic
m/s? impedance is 300ohms and the load is 600
ohms? Assume a quarter wavelength section
a.0.23 rad/m only
b.0.25 rad/m
c.0.24 rad/m a. 180 ohms
d. 0.26 rad/m  b. 170 ohms
c. 160 ohms
Solution: d. 150 ohms






Solution:
 
Zin= Zo (
  
   
)





  
For l=

 line,
   

 = 0.25 rad/m Zin= (



 ) =  
 


96. Determine the conductance o f a two wire 98. Determine the standing wave ratio of a
open line with the following parameters: D 300 ohms line whose load is 400 +j 150
= 4inches ; d= 1in and = 2.6 x10 8 -m. ohms.

-9
a. 2.76 x 10 S/m a. 1.68
-9
 b. 2.77 x 10 S/m b. 1.67
-9
c. 2.78 x 10 S/m c. 1.66
d. 2.79 x 10 -9 S/m d. 1.65

Solution: Solution:
 SWR =


and the capacitance is 75 pf/m.
A. 1.015 µh

 
 
 
 

 
B. 2.250 µh
C. 1.025µh
D. 2.450 µh
Solution:
= 0.25 < 44.22

 Zo =  
SWR =
 

= 1.67 L = Zo C
2

2 -12
L = (52) (75x10 )
L = 203 nH/m
L = 203 nH/m (5 meter)
L = 1.015µH
99. What proportion of the incident is
reflected back from the loadfor a 75ohms 101.An open wire line with a 2mm
line terminated with Zl = 50-j25 ohms? diameter each separated by 12mm.
Calculate the char impedance.
A. 298 
a. 7.82%
B. 250 
 b. 7.83%
C. 300 
c. 7.84% D. 450 
d. 7.85% Solution:

Solution: Zo =
  

log ( )
   


 






Zo =


  

log
 


Zo = 298 
      
   / /<0
102.A coaxial cable with inner diameter 

 
 

of 3mm and an outer diameter of 
9mm. Determine the characteristic
impedance if the dielectric is

 
  
 
 polyethylene having r = 2.3
A. 43.4
B. 50.2 
C. 32.6 
 

= 7.84% D. 47.7 

100.Find the inductance of a meter  Solution:

length transmission line if the
characteristic impedance is 52 ohms Zo =
  
log ( )
 Zo =
 
   log ( ) 105.Calculate the SWR of the line is the
75 and is terminated by 50
Zo = 43.4 A. 1.5
B. 1.6
103.A coaxial transmission line uses C. 1.7
Teflon as a dielectric (r  = 2.1). D. 1.8
What is the propagation velocity of  Solution:
the signal?
A. 207x106 m/s SWR =


=

  = 1.5
B. 301x106 m/s
C. 245x106 m/s 106.A transmitter sends a 5W of power 
D. 195x106 m/s to a 75 line. Suppose the
Solution: transmitter and the line is matched

Vf =
   but the load is not. Determine the
 power absorbed by the load if the
Vf =
 

coefficient of reflection is 0. 75.
A. 2.1875 W
Vf = 0.69 B. 3.1875 W
Vp = VfC C. 4.1875 W
Vp = 0.69 ( 3x108 ) D. 5.1875 W
Vp = 207x106 m/s Solution:

104.A 530 Mhz signal is propagat ing Pref = 2.8125 W

along a RG 8/u coaxial cable with a PL = Pinc ± Pref 
velocity factor 0.66. If a 75 degrees PL = 5W ± 2.8125W
 phase shift is needed, what is the PL = 2.1875W
length of the transmission line?
A. 7.8 cm 107.A generator sends a 250 W of power 
B. 8.5 cm down a line. If the SWR of the line
C. 5.3 cm is 2.5, determine the power absorbed
D. 6.7 cm  by the load.
Solution: A. 204.1 W
B. 304.1 W
Vp = VfC C. 404.1 W
Vp = 0.66 ( 300x106 ) D.504.1 W
Vp = 198x106 m/s Solution:

 =
   
PL =
 

Pinc

 =

 

= 0.374m
 PL =

PL = 204.1W
250W

L = 0.374 (


) = 0.078cm 108.A 75 characteristic impedance
L = 7.8 cm transmission line is terminated in by
 the load impedance of 120. 110.The transmitter has an output power 
Determine the input impedance of 150W. Suppose the line is 50m
looking into the line 1m long, if the long and perfectly matched with a
line has a velocity factor of 0.9 and loss of 3 db/100m, how much power 
operates at a frequency of 50Mhz. is received in the antenna?
A. 34.4-j12.2 A. 106.2 W
B. 34.4+j12.2 B. 206.2 W
C. 44.4-j12.2 C. 306.2 W
D. 44.4+j12.2 D. 406.2 W
Solution: Solution:

=
  
=
  = 5.4m L = 50m )

=

 (360°) = 66.67 ° L = 1.5 dB
L = 0.173
 
 
)

Zin = Zo
 
  Pout = Pin e-2 L
-2 (0.1 73)
Pout = 150 e

Zin =  

Zin = 34.4 ± j12.2
  
 
 
Pout = 106.2 W

111.TDR equipment receives a signal

250 ns after the test signal had been
109.A parallel tuned circuit is to be transmitted. If the discontinuity of 
constructed from a shorted section the line is found 35m from the test
 point, what is the velocity factor of 
of parallel wire line. If the operating
frequency is 2.4 Ghz and the the line?
A. 0.933
dielectric used is polyethylene, what
is the length of the shorted section? B. 1.933
A. 2.06 cm C. 2.933
B. 3.06 cm D. 3.933
Solution:
C. 4.06 cm
D. 5.06 cm
Solution: d=
 
=

Vf =
  Vf =

Vf =
 

= 0.66 Vf =

 
Vp = VfC
Vp = 0.66 (300x106) = 198x106 m/s Vf = 0.933

 =
  
=
 = 0.0825m 112.The line has 97% velocity factor. If 
two minima are located 30cm apart,
L=
 
=
determine the frequency.
A. 485 Mhz
L = 2.0625 cm B. 585 Mhz
C. 685 Mhz
 D. 785 Mhz characteristic impedance of 75. The
Solution: line is connected through a 15V dc
source and 75 source resistance at
 = 2 (30cm) = 60cm time t=0. The voltage across the
input end changes to 10V, with the
f=
 same polarity as before, at time

f=



 
 t=1.5µs. What is the resistance that
terminates the lines?
f = 485 MHz A. 150
B. 250
113.The power incident in the line is C. 350
200W. Assuming the reflected D. 450
 power is 15W, what is the SWR of  Solution:
the line?
A. 1.75
B. 2.75
V10 =  )Vs

C. 3.75
D.4.75
  
= =1+
Solution:
R=  
 
  
 



    
SWR =
 R= = 150


 
 116.A parallel wire transmission line has
SWR =
  

an inductance of 120 nH/m and a
characteristic impedance of 320.
SWR = 1.75 Calculate the capacitance of the line.
A. 1.17 pF/m
114.A transmission line 90m long has a B. 2.17 pF/m
characteristic impedance of 75.
C. 3.17 pF/m
The line is connected through a 15V D. 4.17 pF/m
dc source and 75 source resistance
Solution:
at time t=0. What is the voltage
across the input immediately after 
t=0?
A. 7.5V
Zo =    
B. 8.5V
C. 9.5 V
C=
 
=

D. 10.5 V C = 1.17 pF/m

117.A radio frequency 50 transmission
Solution: line is connected to a coil with

Vin =
 
= = 7.5 V
internal resistance of 20 and
inductive resistance of 5 at a
frequency of 10Mhz. The line is to
115.A transmission line 90m long has a  be matched to the load by means of 
 a quarter-wave line and a stub that matched, determine the current
are connected across the load. which flows into the line.
Calculate the characteristic A. 100 mA
impedance of the quarter-wave B. 200 mA
transformer. C. 300 mA
A. 32.6  D. 400 mA
B. 42.6  Solution:
C. 52.6 
D. 63.6  Is =


Solution:

YL =
 
= = (47 ±j12) mS
Is =


YL = GL = 47 mS Is = 100mA

ZL =

ZL =
 = 21.3 120. A certain instrument measures the input
Zo =
Zo =
 
   = 32.6
impedance of a line and gave a reading of 
1200 ohms when its far-end terminals open
circuited and 300 ohms when it is short
118.An open-wire line has a 3mm circuited. Calculate the characteristic
diameter separated 6mm from each impedance of the line.
other by an dielectric. Calculate the
characteristic impedance of the line. a.500
A. 166 
b.600 
B. 266 
C. 366 
c.700 
D. 466 
Solution:
d.800 

Zo =
  

log ( )

Zo =
   


log

Solution:
Zo = 166 
   
   

   
  

  

119.A radio frequency coaxial

transmission line has a characteristic
impedance of 50 and is connected 121. A transmission line has an inductance
across the terminals of a signal of 253 nH/m and a capacitance of 56 pF/m.
generator, line and the load are If the physical length of the line is 1.5 m,
calculate its electrical length at a frequency c.166
of 265 MHz.
d.167
a.3/2  
Solution:
 b. 1/2 

c. 4/2 




d. 5/2 
 



Solution:

      

  

 

    

 

 
    
       


 


  
     



 

   

   


 
 



    

123. The reflected current at the load of a

 
mismatched line is 3 mA. If the reflection
coefficient of the load is 0.7, what is the
incident current?

Electrical length = 1.5 m (
 )
a. 4.5
Electrical length = 1.5   b.4.4
Electrical length = 3/2 
c.4.3

d.4.2
122. A radio-frequency transmission line has
Solution:
a capacitance of 46.8 pF/m and a phase
constant of 30° /m. Determine the inductance
of the line at a frequency of 30 MHz.
 



a. 164

b.165
 


 
 
c.57%

     
 
d.58%

Solution:

124. A radio frequency transmission lines

 
 


has a characteristic impedance of 75 ohms.
If the line is terminated by an aer ial with an
input impedance of 72 ohms, calculate the
 


SWR of the line.   



a. 1.01  
  

 b.1.02   
  
c.1.03
  
 
d.1.04
  
 
Solution:
 
   
 






    

  


 126. The reflection coefficient on a loss-
  
free line of 72 ohms characteristic

 

 
    

impedance is 60%. Calculate the load
impedance (purely resistive) and which is
smaller than 72 ohms.

     a.17

b.18

125. A lossless transmission line is c.19

connected to a 10 ohms load. If the SWR=5,
d.20
calculate the percentage of the incident
 power that is dissipated in the load. Solution:

a.55%

b.56%
   




   



  


      
  

     

128. A lossless line has a 75 ohms
characteristic impedance and is connected to

 
1.6 
50 ohms load. If the sending current of 1
mA flows into the line. Calculate the power 
 
 
reflected from the load.

a.1

 b.1
127. A radio frequency 50 ohms
transmission line is connected to a coil with c.3
internal resistance of 20 ohms and induct ive
reactance of 5 ohms at a frequency of 10 d.4
MHz. The line is to be matched to the load
Solution:
 by means of a quarter-wave line and a stub
that are connected across the load. Calculate   
   
the reactance of the stub.
   
 

a.83.2
 
 

   
b.83.3

c.83.4 


d.83.5
 



Solution:
  


 
 
  
 

   
  

  
 

  
   
  

   
  
129. A loss-free line transmission line has

    
an inductance of 263.2 nH/m and a
capacitance of 46.8 pF/m. If the generator 
 

 produces a sinusoidal voltage at 3 MHz of 2
V peak, determine the phase change if the
line is 3 m long.

a. 11.34

 b.11.35

c.11.36

d.11.37

Solution:

  


       

 

   
 

Phase change at 3 meters long:

    
 


  
  