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ECE Objective Questions { Microwave Devices and Circuits }

85. Indicate the false statement :Fourier analysis shows that a sawtooth wave consists of
A. fundamental and sub-harmonic sin waves
B. a fundamental sine wave and an infinite number of harmonics
C. fundamental and harmonic sine waves whose amplitude decreases with the harmonic number

86. When electromagnetic waves are reflected at an angle from a wall, their wavelength along the wall is
A. the same as in free space
B. the same as the wavelength perpendicular to the wall
C. shortended because of the Doppler effect
D. greater than in the actual direction of propagation

87. The Hartley law states that
A. the maximum rate of information transmission depends on the channel bandwith
B. the maximum rate of information depends on the depth of modulation
C. redundancy is essential
D. only binary code may be used

88. A duplexer is used
A. to couple two different antennas to transmitter without utual interference
B. to allow the one antenna to be used for reception or transmission without mutual interference
C. to prevent interference between two antennas when they are connected to a receiver
D. to increase the speed of the pulses in pulsed radar

89. Indicate the false statement regarding the advantages of SSB over doubleside-band, full-carrier AM
A. more channel space is available
B. transmitter circuit must be more stable giving better reception
C. the signal is more noise-resistant
D. much less power is required for the same signal strength

90.  Which of the following frequency bands fall under microwave frequency?
A. UHF and SHF
B. SHF and EHF
D. VLF, LF and MF

91. The wavelength of microwaves at 100 GHz will be
A. 3 cm
B. 0.3 cm
C. 0.03 cm
D. 0.3 cm

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