96. (A) In an oscillation zone of reflex klystron an increase in the reflector voltage results in lighter oscillation frequency.
    (R) Electron bunches pass through the interaction gap before the retarding field is at a maximum and an increased reflector voltage results in the induced current lagging in voltage.
    

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: B

   NA

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97. In microwave radar, pulse repetition frequency is used to resolve range and doppler ambiguities using:
    

1. 1. CW radar
      

   
   
   

   2. Pulsed radar
      

   
   
   

   3. Moving target indicator
      

   
   
   

   4. Pulse-doppler radar

   
   
   

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   NA

   Correct Option: C

   NA

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98. Ionospheric preparation is not possible for microwaves because:
    

1. 1. Microwaves will be fully absorbed by the ionospheric layers
      

   
   
   

   2. There will be an abrupt scattering in all directions

   
   
   

   3. Microwaves will penetrate through the ionospheric layers

   
   
   

   4. There will be dispersion of microwave energy

   
   
   

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   NA

   Correct Option: C

   NA

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99. A microstrip line on alumina substrate (εT = 9) has a zero thickness strip of width, w = 3 mm. Substrate thickness h = 0·5 mm. Assuming TEM wave propagation and negligible fringing field, the characteristic impedance of the line will be approximately:
    

1. 1. 10 Ω
      

   
   
   

   2. 21 Ω
      

   
   
   

   3. 26 Ω
      

   
   
   

   4. 50 Ω

   
   
   

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   NA

   Correct Option: B

   NA

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100. 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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