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Home ‣ Electronics and Communication Engineering ‣ Microwave Communication Comments
  • Question

  • Reflex klystron oscillator is essentially a low power device


  • Options
  • A. True
  • B. False

  • Correct Answer
  • True 

    Explanation
    It uses a single cavity resonator for generating microwave oscillations.

    Its parts are electron gun, resonator, repeller and output coupling.

    It operates on the principle of positive feed back.

    The repeller electrode is at negative potential and sends the partially bunched electron beam back to resonator cavity.

    This positive feedback supports oscillations. Its feature are:

    1. Frequency range - 2 to 100 GHz

    2. Power output - 10 MW to about 2 W

    3. Efficiency - 10 - 20 %

    Its applications include radar receivers, local oscillator in microwave devices, oscillator for microwave measurements in laboratories etc.

    Microwave Communication problems

    Search Results

    • 1. A line is excited by a 100 V dc source. If reflection coefficients at both ends are 1 each then

    • Options
    • A. there will be no oscillations on line
    • B. there will be only 1 or 2 oscillations on line
    • C. there will be a finite number of oscillations on line
    • D. the oscillations will continue indefinitely
      • Discuss
    • 2. Assertion (A): The phenomenon of differential mobility is called transferred electron effect.

      Reason (R): GaAs exhibits transferred electron effect.


    • Options
    • A. Both A and R are correct and R is correct explanation of A
    • B. Both A and R are correct but R is not correct explanation of A
    • C. A is correct but R is wrong
    • D. A is wrong but R is correct
      • Discuss
    • 3. VSB modulation is preferred in TV because

    • Options
    • A. it reduces the bandwidth requirement to half
    • B. it avoids phase distortion at low frequencies
    • C. it results in better reception
    • D. none of the above
      • Discuss
    • 4. The range of a cordless telephone is about

    • Options
    • A. 1000 m
    • B. 500 m
    • C. 100 m
    • D. 10 m
      • Discuss
    • 5. Energy content of atmospheric noise

    • Options
    • A. does not depend on frequency
    • B. decreases as frequency is increased
    • C. increases as frequency is increased
    • D. either (a) or (c) depending on the temperature
      • Discuss
    • 6. A resistive microwave load with ZL = 150 ? is connected to 50 ? coaxial line. SWR is

    • Options
    • A. more than 3
    • B. less than 3
    • C. equal to 3
    • D. either (a) or (c)
      • Discuss
    • 7. Assertion (A): A backward wave oscillator has an internal positive feedback.

      Reason (R): A positive feedback is necessary for sustained oscillations.


    • Options
    • A. Both A and R are correct and R is correct explanation of A
    • B. Both A and R are correct but R is not correct explanation of A
    • C. A is correct but R is wrong
    • D. A is wrong but R is correct
      • Discuss
    • 8. The velocity factor of a transmission line depends on

    • Options
    • A. temperature
    • B. skin effect
    • C. relative permittivity of dielectric
    • D. none of the above
      • Discuss
    • 9. A line has a phase constant of 29.8 rad/m. At 1000 MHz the wavelength is

    • Options
    • A. 29.8 m
    • B. 2.98 m
    • C. 2.1 m
    • D. 0.21 m
      • Discuss
    • 10. The diagram to show distance time history of electrons in klystron amplifier is called

    • Options
    • A. apple gate diagram
    • B. asynchronous diagram
    • C. bunching diagram
    • D. velocity modulation diagram
      • Discuss

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