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ECE Objective Questions { Transmission Lines and Waveguides }



64. A certain transmission line has four discontinuities with reflection co-efficients of j and 6 The 3 ' 4 overall reflection co-efficient on this line is approximately equal to
A. 1/3
B. 3/5
C. 2/3
D. none of these

65. The characteristic impedance of a transmission line is
A. directly proportional to its length
B. inversely proportional to its length
C. independent of its length
D. none of these

66. A given transmission line when open circuited at the load end has an input impedance of (Z1) and when short circuited, it has an input impedance of (Z2). The characteristic impedance of the line is
A. Zo = .A7-7
B. Zo = Z1 Z2
C. Zo = 1127-1-27
D. Zo =Z1

67. Short circuited stubs are preferred over open circuited stubs because the latter
A. have a tendency to radiate
B. are very difficult to design
C. can not be placed at a convenient point
D. none of the above

68. If R, L, G and C are respectively the resistance, inductance, conductance and capacitance per unit length of a transmission line, then the Heaviside condition for a distortionless transmission line is
A.R/C=L/G
B. RC = LG
C.RL=CG
D. none of these

69. An c,pen cipcuited (X14) line has an input impedance of
A. infinity
B. Zo
C. zero
D. none of the above

70. A short circuited (X/4) line has an input impedance of
A. infinity
B. Zo
C. zero
D. none of the above

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