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ECE :: Microwave Communication

  1. What is the numerical aperture an optical fiber when critical angle is 30°?

  2. A.
    0.5
    B.
    0.704
    C.
    0.866
    D.
    0.2

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  3. A line of length slightly less than and short circuited at far end behaves as

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

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  5. In TE10 mode of rectangular waveguide

  6. A.
    there is one half sine wave variation along x direction and one along y direction
    B.
    there is one half sine wave variation along y direction and one along x direction
    C.
    there is one full sine wave variation along x direction and one along y direction
    D.
    none of the above

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  7. Reflection from the object to be measured is significant only when the wavelength is

  8. A.
    much bigger than the size of object
    B.
    much smaller than the size of object
    C.
    almost of the size of object
    D.
    either (a) or (c)

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  9. The speed at which axial electric field due to signal advances in a TWT is equal to

  10. A.
    speed of light
    B.
    (speed of light) (helix pitch helix circumference)
    C.
    (speed of light) (helix circumference helix pitch)
    D.
    (speed of light) (helix pitch) (helix circumference)

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  11. To ensure that only dominant TE10 mode propagates in a rectangular waveguide, the operating frequency

  12. A.
    must be more than cutoff frequency of TE10 mode
    B.
    must be less than cutoff frequency of TE20 mode
    C.
    must be more than cutoff frequency of TE10 mode and less than cutoff frequency of TE20 mode
    D.
    must be less than cutoff frequency of TE10 mode

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  13. In a microwave power measurement using bolometer, the principle of working is variation of

  14. A.
    inductance with absorption of power
    B.
    resistance with absorption of power
    C.
    capacitance with absorption of power
    D.
    cavity dimension with heat generated by power

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  15. Z0 = (Zoc Zsc)0.5

  16. A.
    True
    B.
    False

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  17. A microwave junction is matched at all ports if the S matrix

  18. A.
    has all diagonal elements zero
    B.
    has all diagonal elements equal but not zero
    C.
    has all diagonal elements complex
    D.
    is Hermitian

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  19. Assertion (A): A line of length slightly more than and open circuited at far end is equivalent to an inductive reactance.

    Reason (R): A line of length slightly more than and short circuited at far end behaves as a capacitive reactance.

  20. 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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