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

  • The action of backward wave oscillator is similar to that of


  • Options
  • A. klystron amplifier
  • B. reflex klystron oscillator
  • C. TWT
  • D. magnetron

  • Correct Answer
  • TWT 

    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. SSB Modulation 1. Transmission line
      B. ? . B = 0 2. Hilbert transform
      C. Model dispersion 3. Faraday's law
      4. Absence of magnetic monopoles
      5. Waveguides
      6. Phase locked loop


    • Options
    • A. A-1, B-3, C-5
    • B. A-5, B-4, C-2
    • C. A-6, B-4, C-5
    • D. A-2, B-4, C-5
      • Discuss
    • 2. Match the following:

      List I List II
      A. (? x E)ds = 0 1. Continuity equation
      B. rv.dv = Q 2. Ampere's law
      C. (J + D)ds 3. Gauss law
      D. -rvdv 4. Faraday's law
      E. H.dl = (? x H)ds 5. Stoke's theorem


    • Options
    • A. A-4, B-3, C-2, D-1, E-5
    • B. A-1, B-2, C-3, D-4, E-5
    • C. A-4, B-2, C-1, D-3, E-5
    • D. A-1, B-5, C-4, D-2, E-3
      • Discuss
    • 3. Match the following:

      List I (Command in WORD) List II (Meaning)
      A. END 1. The bar displays the current position of cursor
      B. HOME 2. Moves cursor to the beginning of current line
      C. Status 3. Moves cursor to end of document


    • Options
    • A. A-1, B-2, C-3
    • B. A-3, B-1, C-2
    • C. A-2, B-3, C-1
    • D. A-3, B-2, C-1
      • Discuss
    • 4. Match the following:

      List I List II
      A. Penetration frequency 1. Lowest frequency at which charged particles spiral in fixed magnetic field
      B. Optimum working frequency 2. Same as critical and frequency
      C. Gyro frequency 3. Highest frequency of radio waves that can be used
      D. Maximum usable frequency 4. The most effective frequency for ionosphere propagation of radio waves


    • Options
    • A. A-2, B-4, C-1, D-3
    • B. A-4, B-1, C-3, D-2
    • C. A-1, B-3, C-2, D-4
      • Discuss
    • 5. Match the following:

      List I List II
      A. Output of signal generator 1. Modulated
      B. Error signal from a synchro 2. Digital
      C. Output of a JK flip flop 3. Analog
      D. Signal received by radar 4. Stoichastic


    • Options
    • A. A-1, B-3, C-2, D-4
    • B. A-3, B-1, C-2, D-4
    • C. A-3, B-1, C-4, D-2
    • D. A-1, B-3, C-4, D-2
      • Discuss
    • 6. Match the following:

      List I List II
      A. TV 1. 1 kHz
      B. Radio 2. 3 kHz
      C. Telephony 3. 9 kHz
      D. Telegraphy 4. 5 MHz


    • Options
    • A. A-4, B-1, C-2
    • B. A-4, B-3, C-2
    • C. A-2, B-1, C-3
    • D. A-1, B-2, C-3
      • Discuss
    • 7. The normal operation of JFET is

    • Options
    • A. constant voltage region
    • B. constant current region
    • C. both constant voltage and constant current regions
    • D. either constant voltage or constant current region
      • Discuss
    • 8. Assertion (A): McMurray Bredford half bridge inverter uses complementary commutation

      Reason (R): Three phase inverter can have two modes of operation.


    • Options
    • A. Both A and R are correct and R is correct explanation of A
    • B. Both A and R 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
    • 9. Assuming a minimum angle of elevation of 5°, a geosynchronous satellite remains in line-of-sight for __________ percentage of Earth's surface.

    • Options
    • A. 30.3
    • B. 42.4
    • C. 50
    • D. 25
      • Discuss
    • 10. In a turnstile antenna two-half wave resonant wire radiators are placed at 90° to each other in the same plane and are excited

    • Options
    • A. in phase
    • B. in phase opposition
    • C. 90° out of phase with each other
    • D. 45° out of phase with each other
      • Discuss

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