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  • Question

  • In a TWT the axial component of electric field advances along the tube


  • Options
  • A. at a velocity that is almost equal to speed of light
  • B. at a velocity that is a small fraction of speed of light
  • C. at a velocity that is about 50% of speed of light
  • D. at a velocity that may be even more than speed of light

  • Correct Answer
  • at a velocity that is a small fraction of speed of light 

    Explanation
    In a klystron the resonant structure limits the bandwidth.

    A TWT is a broadband device. Its main components are electron gun (to produce the electron beam) and a structure supporting the slow electromagnetic wave.

    The velocity of wave propagation along the helix structure is less than velocity of light.

    The beam and wave travel along the structure at the same speed.

    Thus interaction occurs between beam and wave and the beam delivers energy to the RF wave.

    Therefore the signal gets strengthened and amplified output is delivered at the other end of tube.

    The main features of TWT are :

    1. Frequency range - 0.5 GHz to 90 GHz

    2. Power output - 5 mW at low frequencies(less than 20 GHz) 250 kW (continuous wave) at 3 GHz 10 MW (pulsed) at 3 GHz

    3. Efficiency - about 5 to 20%

    4. Noise - about 5 dB for low power TWT 25 dB for high power TWT

    TWT is used as RF amplifier in broadband microwave receivers, repeater amplifier in broad band communication systems, communication satellites etc.

    More questions

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    • Options
    • A. True
    • B. False
      • Discuss
    • 2. The output frequency of a cycloconverter can be changed by changing the firing angle.

    • Options
    • A. True
    • B. False
      • Discuss
    • 3. Most of the memory chips in static RAM

    • Options
    • A. do not require any supply
    • B. need 2 V supply
    • C. need 5 V supply
    • D. need 12 V supply
      • Discuss
    • 4. In crystalline solids, atoms are stacked in a regular manner.

    • Options
    • A. True
    • B. False
      • Discuss
    • 5. The classes of solid dielectrics are

    • Options
    • A. A, B, C, D, E, F, H
    • B. A E B F H C D
    • C. Y A E B F H C
    • D. A E B F H C
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    • 6. The unit for mmf is

    • Options
    • A. A
    • B. Wb
    • C. T
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    • 7. In a single phase full wave regulator, the firing angles in the positive and negative half cycles are generally

    • Options
    • A. equal
    • B. different
    • C. equal or different
    • D. different but sometimes equal
      • Discuss
    • 8. The real part of complex dielectric constant and tan? for a dielectric are 2.1 and 5 x 10-4 at 100 Hz respectively. The imaginary part of dielectric constant at 100 Hz is

    • Options
    • A. 1.05 x 10-3
    • B. 2.1 x 10-3
    • C. 5 x 10-3
    • D. 1.05 x 10-2
      • Discuss
    • 9. The units for ?r are

    • Options
    • A. Farads
    • B. Farads/m
    • C.
    • D. no units
      • Discuss
    • 10. Tesla is a unit of

    • Options
    • A. flux
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