113. The biggest disadvantage of the IMPATT diode is its
A. low efficiency than the other microwave diodes
B. low power handling ability
C. high noise
D. inability to provide pulsed operation

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114. One of the following which diode is not used as a microwave mixer or detector?
A. PIN diode
B. Crystal diode
C. Schottky barrier diode
D. Backward diode

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115. One of the following microwave diodes is suitable for very low-power oscillator only
A. Tunnel
B. Gunn
C. IMPA'TT
D. LSA

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116.  Noise figure is used as figure of merit of
A. Oscillator
B.Amplifier
C. Moderator
D. Isolator

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117. Strapping is used in cavity magnetron to
A. ensure bunching
B. prevent cathode-back heating
C. improve the phase focusing effect
D. prevent mode jumping

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118. The angle between electric and magnetic fields in a waveguide is
A. 90?
B.0
C. 180?
D.3600

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119. The average thermal noise is
A. constant as long as the bandwidth is fixed
B. dependent on channel loading
C. due to amplitude non-linearity in system
D. not related to the microwave comunication at all

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