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ECE :: Electromagnetic Field Thoery

Electromagnetic Field Thoery - Section 1
Electromagnetic Field Thoery - Section 2
Electromagnetic Field Thoery - Section 3
Electromagnetic Field Thoery - Section 4
Electromagnetic Field Thoery - Section 5
Electromagnetic Field Thoery - Section 6
Electromagnetic Field Thoery - Section 7
Electromagnetic Field Thoery - Section 8
Electromagnetic Field Thoery - Section 9
Electromagnetic Field Thoery - Section 10
Electromagnetic Field Thoery - Section 11
Electromagnetic Field Thoery - Section 12
Electromagnetic Field Thoery - Section 13
Electromagnetic Field Thoery - section-14
Electromagnetic Field Thoery - section-15

  1. MF is generally used for

    2. A.
    telegraphy
    B.
    radio and television links
    C.
    satellite communication
    D.
    broadcasting, navigation

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  2. The attenuation in waveguides near the cut off frequency is

    3. A.
    very low
    B.
    very high
    C.
    medium
    D.
    zero

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  3. The ground waves eventually disappear as one moves away from the transmitter because of

    4. A.
    tilting
    B.
    maximum single-hop distance limitation
    C.
    interference from the sky waves
    D.
    loss of line-of sight condition

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  4. The radiation resistance of a rod tubing antenna is

    5. A.
    55 Ω to 60 Ω
    B.
    60 to 100 Ω
    C.
    0 to 377 Ω
    D.
    60 to 200 Ω

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  5. Power gain of an antenna in a given direction is the ratio of

    6. A.
    average power to maximum power
    B.
    radiation intensity in that direction to the total input radiated power
    C.
    radiation intensity in that direction to the average radiated power
    D.
    none of the above

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  6. The secondary lobes in binomial arrays can be reduced by

    7. A.
    maintaining spacing between two consecutive radiating sources less than λ/2
    B.
    maintaining the amplitudes in radiating sources, from outer towards the centre source, proportional to the coefficients of the successive terms of the binomial series
    C.
    both (a) and (b)
    D.
    none of the above

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  7. Which of the following statement is incorrect?

    8. A.
    Curl of vector potential is magnetic field density
    B.
    Electric charges in motion produce magnetic field
    C.
    Electric charges at rest produce electrostatic field
    D.
    None of the above

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  8. The maximum effective aperture of a microwave antenna which has a directivity of 900, will be

    9. A.
    71.619 λ2
    B.
    716.19 λ2
    C.
    7161.9 λ2
    D.
    71619 λ2

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  9. For a wave propagating in air filled rectangular waveguide.

    10. A.
    guide wavelength is never less than free space wavelength.
    B.
    wave impedance is never less than the free space impedance
    C.
    TEM mode is possible if the dimension of the waveguide are properly chosen.
    D.
    propagation constant is a real quantity.

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  10. Which of following antenna produces elliptical polarisation?

    11. A.
    Helical
    B.
    Parabolic
    C.
    Dipole
    D.
    None

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