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ECE :: Microwave Communication

  1. In which of the following devices can the operation be visualised in terms of a series feedback loops?

  2. A.
    TWT
    B.
    Reflex klystron
    C.
    Klystron amplifier
    D.
    Backward wave oscillator

  3. The first and second subscripts in models of circular waveguides depict

  4. A.
    the number of full sine wave variations in circumference in direction and Bessel function variations in radial direction respectively
    B.
    the Bessel function variations in radial direction and the number of full sine wave variations in circumference direction respectively
    C.
    the Bessel function variations in circumference direction and number of full sine wave variations in radial direction respectively
    D.
    none of the above

  5. In which mode of circular waveguide does the attenuation continuously decrease as frequency is increased?

  6. A.
    TE01
    B.
    TE11
    C.
    TE05
    D.
    TE21

  7. In which mode of rectangular waveguide are all field components zero?

  8. A.
    TM00
    B.
    TM11
    C.
    TM01
    D.
    TM10

  9. A microstrip line has dielectric having relative permittivity ∈r. The effective dielectric constant is

  10. A.
    more than ∈r
    B.
    equal to 1
    C.
    less than ∈r
    D.
    either a or b

  11. The rotation of direction of E field of a linearly polarized wave passing through a magnetised ferric medium is called

  12. A.
    Lorentz rotation
    B.
    Faraday rotation
    C.
    Steinmitz rotation
    D.
    Fleming's rotation

  13. If air pressure in a rectangular waveguide is increased the maximum power handling capacity

  14. A.
    is decreased
    B.
    is increased
    C.
    remains the same
    D.
    may increase or decrease depending on pressure

  15. A directional coupler is used to determine

  16. A.
    rv
    B.
    rv and VSWR
    C.
    L and C
    D.
    wave velocity

  17. A square waveguide carries TE11 mode whose axial magnetic field is given by Hz = H0 , where the guide dimensions are in cms. The cut off frequency of the mode is

  18. A.
    5 GHz
    B.
    7.5 GHz
    C.
    6.5 GHz
    D.
    8 GHz

  19. For air filled circular waveguides

  20. A.
    the attenuation due to imperfect conducting walls is negligible
    B.
    the attenuation due to imperfect dielectric is negligible
    C.
    both the attenuation i.e. due to imperfect conducting walls and due to imperfect dielectric are significant
    D.
    the total attenuation is almost zero