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ECE :: Electromagnetic Field Thoery

  1. Which one is not correct for folded dipole antenna?

  2. A.
    High I/P impedance
    B.
    Low I/P impedance
    C.
    High bandwidth
    D.
    Used as reactance compensation network

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  3. For VLF antennas radiation resistance is usually of the order of

  4. A.
    less than one ohm
    B.
    13 to 20 ohms
    C.
    around 100 ohms
    D.
    more than 200 ohms

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  5. The attenuation factor in parallel plane guides is given by

  6. A.
    a = power lost/power transmitted
    B.
    a = 2 x power lost/power transmitted
    C.
    a = power lost per unit length/2 x power transmitted
    D.
    a is always constant

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  7. Which of the following relations is incorrect?

  8. A.
    mmf x reluctance = 1
    B.
    conductance x resistance = 1
    C.
    D.
    none of the above

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  9. An antenna array pattern is to used for increasing

  10. A.
    gain
    B.
    directivity
    C.
    directive gain
    D.
    all

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  11. A unipole is also known as

  12. A.
    omnidirectional radiator
    B.
    unidirectional radiator
    C.
    line radiator
    D.
    none of the above

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  13. Microwave signals follow the curvature of the earth and the phenomenon

  14. A.
    tropospheric scatter
    B.
    faraday effect
    C.
    duct propagation
    D.
    none

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  15. Broadcasting antennas are generally

  16. A.
    omnidirectional type
    B.
    vertical type
    C.
    horizontal type
    D.
    helical

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  17. A transmission line has characteristics impedance of (75 + j 0.01) Ω and is terminated in a load impedance of (70 + j 50) Ω. The reflection coefficient will be

  18. A.
    0.08 + j 0.32
    B.
    0.32 + j 1.38
    C.
    0.70 - j 2.97
    D.
    1.1 + j 0.32

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  19. Which of the following term does not apply to the Yagi-Uda array?

  20. A.
    High gain
    B.
    Folded dipole
    C.
    Parasitic
    D.
    Good bandwidth

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