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Home ‣ Electronics and Communication Engineering ‣ Microwave Communication See What Others Are Saying!
  • Question

  • In a backward wave oscillator the wave


  • Options
  • A. travelling along the line winds itself back and forth
  • B. progresses only in forward direction
  • C. progresses only in backward direction
  • D. either (a) or (c)

  • Correct Answer
  • travelling along the line winds itself back and forth 

    Explanation
    It is somewhat similar to TWT and can deliver microwave power over a wide frequency band.

    It has an electron gun and a helix structure. However the interaction between electron beam and RF wave is different than in TWT.

    The growing RF wave travels in opposite direction to the electron beam.

    The frequency of wave can be changed by changing the voltage which controls the beam velocity.

    Moreover the amplitude of oscillations can be decreased continuously to zero by changing the beam current.

    It features are:

    1. Frequency range - 1 GHz to 1000 GHz.

    2. Power output - 10 mV to 150 mW (continuous wave) 250kW (pulsed).

    It is used as signal source in transmitters and instruments.

    More questions

    • 1. Match the following:

      List I List II
      A. VOH(min) 1. 2.4 V
      B. VIH(min) 2. 1.5 V
      C. VOL(max) 3. 0.4 V
      4. 2.0 V
      5. 0.8 V


    • Options
    • A. A-1, B-3, C-4
    • B. A-1, B-4, C-3
    • C. A-5, B-4, C-3
    • D. A-1, B-5, C-2
      • Discuss
    • 2. To couple a coaxial line to a parallel wire line it is best to use

    • Options
    • A. slotted line
    • B. balun
    • C. directional coupler
    • D. ?/4 transformer
      • Discuss
    • 3. A single phase full converter gives maximum and minimum output voltage at firing angles of

    • Options
    • A. 0 and 180° respectively
    • B. 180° and 0° respectively
    • C. 0 and 90° respectively
    • D. 90° and 0° respectively
      • Discuss
    • 4. 1's complement of 11100110 is

    • Options
    • A. 00011001
    • B. 10000001
    • C. 00011010
    • D. 00000000
      • Discuss
    • 5. Thyristors connected in series need :

    • Options
    • A. static equalizing circuit
    • B. dynamic equalizing circuit
    • C. both static and dynamic equalizing circuits
    • D. none of the above
      • Discuss
    • 6. For a first order system having transfer function , the unit impulse response is

    • Options
    • A. e-t/T
    • B. T e-t/T
    • C.
    • D. T2 e-t/T
      • Discuss
    • 7. In a single phase full wave controlled rectifier using centre tap transformer, the voltage across each half of secondary is Vm sin ?t. The peak inverse voltage is

    • Options
    • A. 2 Vm
    • B. Vm
    • C. 0.5 Vm
    • D. 0.25 Vm
      • Discuss
    • 8. A single phase full wave regulator feeds a resistive load. The firing angle of thyristors is 90°. The input power factor is

    • Options
    • A. 1
    • B. 0.707 lagging
    • C. 0.5 lagging
    • D. 0.2 lagging
      • Discuss
    • 9. The final value theorem is

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 10. Find Vx Vy Vz

    • Options
    • A. Vx = -6 Vy = 3 Vz = -3
    • B. Vx = -6 Vy = -3 Vz = 1
    • C. Vx = 6 Vy = 3 Vz = 3
    • D. Vx = 6 Vy = 1 Vz = 3
      • Discuss

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