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ECE :: Microwave Communication

  1. Which of the following parameters is negligible in transmission lines?

  2. A.
    R
    B.
    L
    C.
    C
    D.
    G

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  3. The width of a radio beam from a 1 m diameter parabolic antenna at 10 GHz is about

  4. A.
    100°
    B.
    50°
    C.
    D.

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  5. The diagram to show distance time history of electrons in klystron amplifier is called

  6. A.
    apple gate diagram
    B.
    asynchronous diagram
    C.
    bunching diagram
    D.
    velocity modulation diagram

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  7. Impedance level of Impatt diodes is generally lower than that of Gunn diodes

  8. A.
    True
    B.
    False

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  9. A quarter wave line open circuited at far end behaves as

  10. A.
    inductance
    B.
    L and C in parallel
    C.
    capacitance
    D.
    L and C in series

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  11. A line has Z0 = 300 ∠ 0° Ω. If ZL = 150 ∠ 0° Ω, reflection coefficient is

  12. A.
    0.5
    B.
    0.3333
    C.
    -0.3333
    D.
    -0.5

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  13. Assertion (A): A backward wave oscillator has an internal positive feedback.

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

  14. 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

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  15. In a microstrip transmission the signal can be easily redirected by changing the centre strip.

  16. A.
    True
    B.
    False

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  17. The frequency of oscillation in a backward wave oscillator can be changed by

  18. A.
    varying the voltage which controls beam velocity
    B.
    varying the beam current
    C.
    both by varying the beam current and by light varying the voltage which controls beam velocity
    D.
    changing the rate of thermionic emission

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  19. A line has a phase constant of 29.8 rad/m. At 1000 MHz the wavelength is

  20. A.
    29.8 m
    B.
    2.98 m
    C.
    2.1 m
    D.
    0.21 m

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