31. Match list-I with list-II and select the correct answer using the codes given below the lists:

    List-I (Microwave Devices)	List-II (Applications)
    A. Reflex klystron	1. Wide band amplification
    B. TWT	2. Very low level amplification
    C. 2-Cavity klystron	3. Low power FM generation
    D. Maser	4. Frequency multiplication

1. 1. A B C D
      1 2 3 4
      

   
   
   

   2. A B C D
      4 3 2 1
      

   
   
   

   3. A B C D
      3 4 1 2
      

   
   
   

   4. A B C D
      3 1 4 2
      

   
   
   

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   NA

   Correct Option: D

   NA

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32. (A) The TW tube which is a wideband microwave amplifier of the helix is used as a slow wave structure of the device.
    (R) The phase velocity of the helix can be profiled along the length of the helix.

1. 1. Both A and R are true and R is correct explanation of A

   
   
   

   2. Both A and R are true but R is not a correct explanation of A

   
   
   

   3. A is true but R is false

   
   
   

   4. A is false but R is true

   
   
   

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   NA

   Correct Option: A

   NA

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33. A calorimetric measurement for average power of a signal gave a value of 400 W. The value was interpreted for peak power as 0·5 mW. Then the duty cycle of the signal is:
    

1. 1. 0·08%
      

   
   
   

   2. 8%
      

   
   
   

   3. 40%
      

   
   
   

   4. 80%

   
   
   

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   NA

   Correct Option: A

   NA

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34. In microwave power measurements using bolometer, the principle of working is the variation of:
    

1. 1. Inductance with absorption of power
      

   
   
   

   2. Resistance with absorption of power
      

   
   
   

   3. Capacitance with absorption of power
      

   
   
   

   4. Cavity dimensions with heat generated by the power

   
   
   

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   NA

   Correct Option: B

   NA

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35. Consider the following statements regarding feed which is the Key component of a reflector antenna as it has a decisive bearing on the overall-performance:
    1. For a horn-feed antenna the reflector focus must coincide with horn-feeds phase centre, which for a wide-flare horn lies in the plane of horn aperture.
    2. The feed must have minimal radiation outside the angular aperture of reflector.
    3. In print focus or cassegrain systems, the main or sub-reflectors should be in Fraunhofer zone of the feed antenna.
    Which of the statements are correct?
    

1. 1. 1, 2 and 3
      

   
   
   

   2. 1 and 2
      

   
   
   

   3. 2 and 3
      

   
   
   

   4. 1 and 3

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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