Transmission Lines

MULTIPLE CHOICE QUESTIONS IN

TRANSMISSION LINES Electronics Systems and Technologies By Melvin C. Arceo

ENCODED BY: ANDRADE, Caroline T. 1. Category of media with some form of conductor t hat provides a conduit in which electromagnetic signals are contained. A. B. C. D.

Guided Balanced Unguided Unbalanced

2. The conductive connections between elements which carry signals. A. B. C. D.

Transmission Lines Antenna Frequency allocations Load

3. Calculate the characteristic impedance for a line that exhibits an inductance of 4 nH/m and 1.5pF/m A. B. C. D.

36.6 ohms 51.6 ohms 22 ohms 24.5 ohms

4. Category of media which are wireless A. B. C. D.

Guided Balanced Unguided Unbalanced

5. It is a medium or any physical facility used to propagate electromagnetic signals between two locations in a communications system. A. B. C. D.

Transmission medium Channel allocation Frequency allocation Any of these

6. It is a metallic conductor system used to transfer electrical energy from one point to another using electrical current flow. A. Transmitter B. Multiplexers C. Receiver D. Transmission line 7. A kind of wave where the displacement is in the direction of propagation.

A. B. C. D.

Transverse Longitudinal Reverse Perpendicular

8. Calculate the capacitance per meter of a 50-ohm load cable that has an inductance of 55 nH/m. A. B. C. D.

13 pF 18 pF 20 pF 22 pF

9. The desirable SWR on a transmission line is A. B. C. D.

0 1 2 Infinity

10. A kind of wave where the direction is displacement is perpendicular to the direction of  propagation. A. B. C. D.

Transverse Longitudinal Reverse Perpendicular

11. A short-circuited half-wavelength line acts like a A. B. C. D.

Parallel resonant circuit Series Resonant Circuit Oscillator LC circuit

12. Electromagnetic waves that travel along a transmission line from the source to the load. A. Reverse waves B. Transverse waves C. Incident waves

D. Longitudinal waves 13. Electromagnetic waves that travel from the load back toward the source. A. B. C. D.

Incident waves Transverse waves Forward waves Reflected waves

14. Sound travels approximately A. B. C. D.

2200 feet per second 1100 feet per second 550 feet per second 600 feet per second

15. Determine the surge impedance for a parallel wire, air d ielectric with a ratio of the spacing between conductors and the diameter of 3 A. B. C. D.

250 ohms 210 ohms 180 ohms 215 ohms

16. The rate at which the periodic wave repeats A. B. C. D.

Wavelength Amplitude Period Frequency

17. The distance of one cycle occurring in space A. B. C. D.

Wavelength Amplitudes Period Frequency

18. Classification of transmission line where both conductors carry current; one conductor carries the signal, the other conductor is the return path

A. B. C. D.

Differential transmission lines Unbalanced lines Coaxial cables Balun

19. A shorted half-wave line at the operating frequency a cts like A. B. C. D.

Capacitor Inductor Series resonant circuit Parallel resonant circuit

20. What is the characteristic impedance of a coaxial line, air dielectric with a ratio of the diameter of the outer and inner conductor equal to 1.5? A. B. C. D.

24.3 ohms 25.6 ohms 13.2 ohms 18 ohms

21. Currents that flow in opposite direction in a balanced wire pair is called A. B. C. D.

Longitudinal currents Reverse circuit currents Transverse circuit currents Metallic circuit currents

22. Currents that flow in same direction in a balanced wire pair is called A. B. C. D.

Longitudinal currents Reverse circuit currents Transverse circuit currents In-phase currents

23. A circuit device used to connect a balanced transmission line to an unbalanced load A. Slotted lines B. Stub C. Balun

D. Quarterwave lines 24. The most common type of balun used in relatively high frequency A.  Narrowband B. Choke C. Sleeve D. All of these 25. A pattern of voltage and current variations along the transmission line not terminated in its characteristic impedance is called A. B. C. D.

An electric fluid Radio waves Standing waves A magnetic field

26. A type of parallel-conductor transmission lines consists of simply of two parallel wires, closely-spaced and separated by air. A. B. C. D.

Twisted pair Open-wire lines Coaxial cables Twin pair

27. A type of parallel-conductor transmission lines which is essentially the same as open wire transmission line except that the spacers between the conductors are replaced with a continuous solid dielectric that ensures uniform spacing along the entire cab le A. B. C. D.

Twisted pair Open-wire lines Coaxial cables Twin lead

28. What is the range of size of wires of a twisted pair? A. B. C. D.

AWG 16 to AWG 26 AWG 14 to AWG 25 AWG 10 to AWG 20 AWG 12 to AWG 28

29. What is the characteristic impedance of a coaxial line, polyethylene dielectric with the ratio of the diameter of the outer and the inner conductor of 2.5? A. B. C. D.

43.5 ohms 23.4 ohms 36.2 ohms 29.8 ohms

30. In AWG, the higher the wire gauge ______ A. B. C. D.

The higher the diameter and the lower the resistance The smaller the diameter and the higher the resistance The smaller the diameter and the higher the conductance The larger the diameter and the higher the resistance

31. Type of twisted pair wire cable that consists of two co pper wires where each wire is separately encapsulated in PVC insulation. A. B. C. D.

Shielded twisted pair Twin lead Unshielded twisted pair Open wire frame

32. A shorted quarter-wave line at the operating frequenc y acts like A. B. C. D.

Series resonant circuit Parallel resonant circuit Capacitor Inductor

33. The minimum number of twist for UTP is A. B. C. D.

Two twist per foot Two twist per meter Three twist per foot Three twist per meter

34. A delay line using RG-8A/U cable is to exhibit a 5-ns delay. Calculate the required length of the cable. A. 4.57 ft B. 1.23 ft

C. 6.2 ft D. 3.4 ft 35. An open-circuited quarter-wavelength line acts like a A. B. C. D.

Parallel resonant circuit Series resonant circuit Oscillator LC circuit

36. Level for category of UTP cable which is suitable only for voice grade telephone signals and very low-speed data applications A. B. C. D.

Level 1 or Cat 1 Level 3 or Cat 3 Level 2 or Cat 2 Cat 4

37. An antenna is being fed by a properly terminated two-wire transmission line. The current in the line at the input end is 3A. The surge impedance of the line is 500 ohms. How much power is being supplied to the line? A. B. C. D.

3.1 kW 2.5 kW 1.6 kW 4.5 kW

38. Level or Category of UTP cable which was developed for IEEE 802.5 token ring local area networks operating at a transmission rates of 4Mbps A. B. C. D.

Level 1 or Cat 1 Level 3 or Cat 3 Level 2 or Cat 2 Cat 4

39. If the period of one complete cycle of a radio wave is 0.000001 s, what is the wavelength? A. B. C. D.

300 m 200 m 100 m 400 m

40. If the two towers of a 950-kHz antenna are separated by 120 electrical degrees, what is the tower separation in feet?

A. B. C. D.

231 ft 235 ft 176 ft 345 ft

41. Category of UTP used for virtually any voice o r data transmission rate up to 16 Mbps, has a minimum of 3 turns per inch. A. B. C. D.

Category 5e Category 4 Category 5 Category 3

42. The mismatch between the antenna and transmission line impedances cannot be corrected for by A. B. C. D.

Using an LC matching network Adjusting antenna length Using a balun Adjusting the length of transmission line

43. Category of UTP that was designed for data transmission rates up to 20 Mbps A. B. C. D.

Category 5e Category 4 Category 5 Category 3

44. Variation of CAT5 cables that are intended for dat a transmission rates up to 250 Mbps A. B. C. D.

Category 5e Category 2 Category 6 Category 3

45. A type of twisted-pair wherein its wires and dielectric are enclosed in a conductive metal sleeve called a foil. A. B. C. D.

STP Twin lead UTP Unshielded Twin lead

46. It is the name given to the area between the ceiling and the roof in a single-story building or between the ceiling and the floor of the next higher level in a multistory building. A. B. C. D.

Attic Rooftop Plenum Ceiling

47. It consists of center conductor surrounded by dielectric material, then a concentric shielding, and an environmental protection outer jacket. A. B. C. D.

Twisted pair Coaxial cable Twin lead Open wire

48. In a transmission line, it refers to the woven stranded mesh or braid that surround some types of coaxial cables A. B. C. D.

Grounding Shielding Degaussing Any of these

49. A coaxial cable with one layer of foil insulation and one layer of braided shielding. A. B. C. D.

Backup shielding Temporary shielding Dual shielding Interference shielding

50. At very high frequencies, transmission lines are used as A. B. C. D.

Tuned circuits Antennas Insulators Resistors

51. A coaxial cable with two layers of foil insulation and two layers of braided shielding. A. B. C. D.

Quad shielding Double shielding Triple shielding Shielding

52. A type of coaxial cable that has a tubular outer conductor surrounds the center conductor coaxially and the insulating material is air A. B. C. D.

Rigid air coaxial cable Gas-filled coaxial cable Solid coaxial cable Flexible cable

53. If the length of an open-circuited stub is less than quarter-wavelength but greater than 0, the stub behaves as A. B. C. D.

Inductor Capacitor Resistor Complex

54. Type of coaxial cable where the outer conductor is braided, flexible, and coaxial to the center conductor. A. B. C. D.

Gas-filled coaxial cable Rigid air coaxial cable Solid flexible coaxial cable Flexible cable

55. A 50-ohm coax is connected to a 73-ohm antenna. The SWR is A. B. C. D.

0.685 1 1.46 2.92

56. Defined as the impedance seen looking at an infinitely long line or the impedance seen looking into a finite length of the line that is terminated in a purely resistive load with the resistance equal to the characteristic impedance of the line. A. B. C. D.

Input impedance Surge impedance Output impedance Circuit impedance

57. Determine the characteristic impedance for an air dielectric two-wire parallel transmission line with a D/r ratio of 12.22 A. 150 ohms B. 120 ohms

C. 75 ohms D. 300 ohms 58. Determine the characteristic impedance for an RG-59A coax ial cable with the following specifications: d=0.025 inches, D=0.15 inches, and dielectric constant of 2.23 A. B. C. D.

120 ohms 72 ohms 150 ohms 75 ohms

59. Determine the characteristic impedance for an RG-59A coax ial cable with the following specifications: L=0.118 uH/ft and C=21 pF/ft A. B. C. D.

150 ohms 72 ohms 75 ohms 100 ohms

60. It is used to express the attenuation or signal loss and the phase shift per unit length of the transmission line. A. B. C. D.

Propagation coefficient Propagation constant Propagation factor Any of these

61. For matched condition, what is the relationship of load and characteristic impedance? A. B. C. D.

Greater than Less than Equal Impossible to say

62. It is defined simply as the ratio of the actual veloc ity of propagation of an electromagnetic wave through a given medium to the velocity of propagation through a vacuum or free space. A. B. C. D.

Velocity factor Velocity propagation Index of refraction Phase delay

63. It is simply the permittivity of the material

A. B. C. D.

Permittivity Insulation constant Dielectric constant Resistivity

64. For a given length of RG 8A/U coaxial cable with distributed capacitance of 96.6 pF/m, a distributed inductance of 241.56 nH/m, and a relative dielectric constant of 2.3, determine the velocity of propagation A. B. C. D.

1.07 x 10^8 m/s 2.3 x 10^7 m/s 3.28 x 10^8 m/s 2.07 x 10^8 m/s

65. For a given length of RG 8A/U coaxial cable with distributed capacitance of 96.6 pF/m, a distributed inductance of 241.56 nH/m, and a relative dielectric constant of 2.3, determine the velocity factor A. B. C. D.

1.2 0.66 0.7 0.5

66. If the length of an open-circuited stub is greater than quarter-wavelength but less than half-wavelength, the stub behaves as A. B. C. D.

Inductor Capacitor Resistor Complex

67. Delay line is a function of what two parameters? A. B. C. D.

Resistance and capacitance Resistance and susceptance Inductance and resistance Inductance and capacitance

68. How is the time delay calculated in a coaxial cables with a dielectric constant of 0.66? A. B. C. D.

0.56 sec 0.67 sec 0.45 sec 1.2 sec

69. Three feet is one wavelength at a frequency of A. B. C. D.

100 MHz 164 MHz 300 MHz 328 MHz

70. When current flows through a conductor, the loss introduced as a function of resistance and current is called _______ A. B. C. D.

Inductance loss Conductor loss Voltage loss Skin effect

71. For maximum absorption of power at the antenna, the relationship between the characteristic impedance of the line Zo and the load impedance ZL should be A. B. C. D.

Zo = ZL Zo > ZL Zo < ZL Zo = 0

72. The ratio of the AC resistance and the DC resistance A. B. C. D.

Impedance ratio Susceptance ratio Resistance ratio Conductance ratio

73. The difference in potential between two conducto rs of a metallic transmission line causes  ______. A. B. C. D.

Conductor loss Dielectric heating Radiation loss Corona

74. If the length of a short-circuited stub is greater than qu arter-wavelength but less than halfwavelength, the stub behaves as A. Inductor B. Capacitor C. Resistor

D. Complex 75. If the separation between the conductors in a metallic transmission line is an appreciable fraction of a wavelength, the electrostatic and elec tromagnetic fields that surround the conductor cause the line to act as if it were an antenna and transfer energy to any nearby material. This energy radiated is called ______. A. B. C. D.

Radiation loss Power loss Coupling loss Corona

76. The minimum voltage along a transmission line is 260 V, while the maximum is 390 V. The SWR is A. B. C. D.

0.67 1.0 1.2 1.5

77. It occurs whenever a connection is made to or from a transmission line or when two sections of transmission line are connected together A. B. C. D.

Power loss Coupling loss Radiation loss Resistance loss

78. Which of the following is not a common transmission line impedance? A. B. C. D.

50 ohms 75 ohms 120 ohms 300 ohms

79. It is a luminous discharge that occurs between the two conductors of a transmission line when the difference in potential between them exceeds the breakdown voltage of a dielectric insulator. A. B. C. D.

Resistance loss Corona Radiation loss Power loss

80. Voltage that propagates down the load

A. B. C. D.

Reflected voltage Standing wave ratio Incident voltage Reflection voltage

81. Voltage that propagates from the load towards the source A. B. C. D.

Reflected voltage Standing wave ratio Reflection coefficient Incident voltage

82. A transmission line with no reflected power A. Flat B. Resistive C.  Non resonant line D. Any of these 83. It is a vector quantity that represents the ratio of reflected voltage to incident voltage or the reflected current and the incident current A. B. C. D.

Reflection coefficient Reactive load diagram Standing wave ratio Traveling waves

84. With a mismatched line, two electromagnetic waves traveling in o pposite direction,  present on the line on the same time. A. B. C. D.

Standing wave ratio Reflection coefficient Standing waves Traveling waves

85. The two traveling waves sets up an interference pattern called _______. A. B. C. D.

Standing wave ratio Reflection coefficient Standing waves Traveling waves

86. It is defined as the ratio of the maximum voltage to the minimum voltage or the maximum current to the minimum current of a standing wave in a transmission line.

A. Standing wave ratio B.  Normalized impedance C. Reflection coefficient D. Any of these

87. For a transmission line with an incident voltage of 5 V and a reflected voltage of 3V, determine the reflection coefficient. A. B. C. D.

0.4 0.6 0.5 0.7

88. A ratio expressing the percentage of incident voltage reflected on a transmission line is known as the A. B. C. D.

Velocity factor Standing wave ratio Reflection coefficient Line efficiency

89. There is an impedance inversion in every ______. A. B. C. D.

Half wavelength Quarter wavelength Full wavelength Three-eights of a wavelength

90. The characteristic impedance of a transmission line does not depend upon its A. Length B. Conductor diameter C. Conductor spacing D.  None of these

91. ______ are used to match transmission lines to purely resistive loads whose resistance is not equal to the characteristic impedance of the line. A. B. C. D.

Stub Slotted lines Quarter-wavelength transformer Short circuited lines

92. To match a transmission line with a reactive load _______

A. B. C. D.

Use stub matching Use a slotted line Used a Q-section Use an open circuited lines

93. A technique that can be used to locate an impairment in metallic cable A. B. C. D.

TDR Wattmeter Voltmeter SWR meter

94. A pulse is transmitted down a cable that has a velocity of propagation of 0.8c. The reflected signal is received 1us later. How far down the cable is the impairment? A. B. C. D.

240 m 15 m 60 m 120 m

95. Using TDR, a transmission line impairment is located 3000m from the source. For a velocity propagation of 0.9c, determine the time elapsed from the beginning of the pulse to the reception of the echo A. B. C. D.

11.11 us 10.12 us 22.22 us 21.14 us

96. A flat conductor separated from a ground plan e by an insulating dielectric material A. B. C. D.

Stripline Waveguide Microstrip Coaxial cable

97. A flat conductor sandwich between two ground planes. A. B. C. D.

Stripline Waveguide Microstrip Coaxial cable

98. Indicate the false statement. The SWR on a transmission line is infinity; the line is terminated in A. B. C. D.

A short circuit A complex impedance An open circuit A pure reactance

99. The most commonly used transmission line is a A. B. C. D.

Two-wire balance line Singe wire Three-wire line Coax

100. A short-circuited half-wavelength line acts like a A. B. C. D.

Parallel resonant circuit Series resonant circuit Oscillator LC circuit

101. A (75-j50)-ohm is connected to a coaxial transmission line of Zo = 75 ohms, at 10 GHz. The best method of matching consists of connecting A. B. C. D.

A short-circuited stub at the load An inductive at the load A capacitance at some specific distance from the load A short-circuited stub at some specific distance from the load

102. The velocity factor of a transmission line A. B. C. D.

Depends on the dielectric constant of the material used Increases in velocity along the transmission line Is governed by the skin effect Is higher for a solid dielectric than for air.

103. Impedance inversion may be obtained with A. B. C. D.

A short-circuited stub An open-circuited stub A quarter-wave line A half-wave line

104. The most desirable reflection coefficient is

A. B. C. D.

0 0.5 1 Infinity

105. Short circuited stubs are preferred to open-circuited stub because the latter are A. B. C. D.

More difficult to make and connect Made of a transmission line with different characteristic impedance Liable to radiate Incapable of giving a full range of reactance

106. For transmission-line load matching over a range of frequencies, it is be st to use a A. B. C. D.

Balun Broadband directional coupler Double stub Single stub of adjustable position

107. The main disadvantage of the two-hole directional coupler is A. B. C. D.

Low directional coupling Poor directivity High SWR Narrow bandwidth

108. To couple a coaxial line to a parallel-wire line, it is best to use a A. B. C. D.

Slotted line Balun Directional coupler Quarter-wave transformer

109. A short-circuited quarter-wavelength line acts like a A. B. C. D.

Parallel resonant circuit Series resonant circuit Oscillator LC circuit

110. If the length of a short-circuited stub is less than a quarter-wavelength but greater than 0, the stub behaves as A. Inductor

B. Capacitor C. Resistor D. Complex 111. The depth of penetration of current density resulting from skin effect A. B. C. D.

Skin depth Wire depth Line depth Medium depth

112. Transmission line must be matched to the load to A. B. C. D.

Transfer maximum voltage to the load Transfer maximum current to the load Reduce the load current Transfer maximum power to the load

113. Referred to the dielectric constant of a transmission line material A. B. C. D.

Inductance and capacitance Velocity factor Characteristic impedance Propagation velocity

114. A transmission line containing of two conductors that have equ al resistance per unit length A. B. C. D.

Unbalanced line Open-wire line Balanced line Coaxial cable

115. Which of the following determines the characteristics of a transmission line? A. B. C. D.

Inductance Capacitance Physical dimension Length

116. Category of UTP that was designed for data transmission rates up to 20 Mbps A. Category 5e B. Category 4 C. Category 5

D. Category 3 117. Level 2 or category 2 UTP cables comply with IBM’s _______ specification. A. B. C. D.

Type 1 Type 3 Type 2 Type 4

118. Level 3 or Category 3 UTP cables should have at least ____ twist per inch. A. B. C. D.

1 2 3 4

119. Which of the following is NOT a color code for Category 5 UTP? A. B. C. D.

Blue/white stripe and blue Orange/white stripe and orange Red/white stripe and red Brown/white stripe and brown

120. Shielded-screen twisted-pair cable or SSTP is also known as ________. A. B. C. D.

Cat 5e Cat 7 Cat 6 Cat 8

121. An open-circuited transmission line quarter wavelength long is equivalent t o A. B. C. D.

Parallel resonant circuit Series resonant circuit Inductive Capacitive

122. A short-circuited transmission line more than quarter-wavelength long but shorter than half wavelength is equivalent to _______. A. B. C. D.

Series resonant circuit Inductive Capacitive Parallel resonant circuit

123. A short-circuited transmission line less than quarter-wavelength long. A. B. C. D.

Inductive Capacitive Parallel resonant circuit Series resonant circuit

124. The quarter-wavelength transformer line acts as a transformer with a 1:1 turns ratio when the load resistance is with what relationship with the characteristic impedance of the quarter-wavelength transformer? A. Equal B. Less than C. Greater than D.  None of these

125. The characteristic impedance of a microstrip is equal to _ ____ ohms. A. B. C. D.

50 to 200 25 to 50 100 to 200 50 to 75

126. The quarter-wavelength transformer line acts as a step down transformer when the load resistance is with what relationship with the characteristic impedance of the quarterwavelength transformer? A. Equal B. Less than C. Greater than D.  None of these

127. The typical value of the velocity factor of an open-wire transmission line is A. B. C. D.

0.8 0.7 0.6 0.9

128. If a transmission line is not terminated in its characteristic impedance, _______ will develop along the line. A. Traveling waves B. Standing waves

C. Surge impedance D. Infinite impedance 129. If a load and a line have mismatched impedances, power not absorbed by the load will  be _____. A. B. C. D.

Absorbed Rejected Reflected Removed