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ECE :: Microwave Communication

  1. Assertion (A): A coaxial line is a non-radiating line.

    Reason (R): In a coaxial line the electric and magnetic fields are confined to the region between the concentric conductors.

  2. 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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  3. Reflex klystron oscillator is essentially a low power device

  4. A.
    True
    B.
    False

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  5. A 10 km long line has a characteristic impedance of 400 ohms. If line length is 100 km, the characteristic impedance is

  6. A.
    4000 Ω
    B.
    400 Ω
    C.
    40 Ω
    D.
    4 Ω

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  7. A matched generator (Zg = Z0) with 1 Ω available. If all ports are matched, the power delivered at ports 1, 2, 3 respectively are

  8. A.
    0.5 W, 0.5 W, 0 W
    B.
    0 W, 0 W, 1 W
    C.
    0.33 W each
    D.
    0 W, 0.25 W, 0.25 W

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  9. Which TM mode in rectangular waveguide has lowest cutoff frequency?

  10. A.
    TM11
    B.
    TM01
    C.
    TM10
    D.
    TM21

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  11. A resistive microwave load with ZL = 150 Ω is connected to 50 Ω coaxial line. SWR is

  12. A.
    more than 3
    B.
    less than 3
    C.
    equal to 3
    D.
    either (a) or (c)

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  13. Which of the following devices uses a slow wave structure?

  14. A.
    Klystron two cavity amplifier
    B.
    Klystron multicavity amplifier
    C.
    Reflex klystron oscillator
    D.
    TWT

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  15. In a turnstile antenna two-half wave resonant wire radiators are placed at 90° to each other in the same plane and are excited

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

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  17. A waveguide section in a microwave circuit acts as

  18. A.
    LP filter
    B.
    Bandpass filter
    C.
    HP filter
    D.
    Band stop filter

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  19. In a klystron amplifier dc electron velocity is v0 and dc electron charge density is r0 the dc beam current is

  20. A.
    r0v0
    B.
    r0/v0
    C.
    v0/r0
    D.
    (v0/r0)2

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