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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. An antenna is synonymous to a

    2. A.
    generator
    B.
    transformer
    C.
    regulator
    D.
    reflector

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  2. Alternating current can induce voltage because it has magnetic field which is

    3. A.
    constant
    B.
    time varying
    C.
    stronger field than D.C.
    D.
    closed loop nature.

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  3. Which of the following frequencies cannot be used for reliable beyond-the-horizon terrestrial communications without repeaters?

    4. A.
    25 kHz
    B.
    15 MHz
    C.
    750 MHz
    D.
    12 GHz

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  4. Maximum effective aperture (Ae)max of short dipole antenna is

    5. A.
    1.119 λ2
    B.
    0.119 λ2
    C.
    1.19 λ2
    D.
    1.919 λ2

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  5. Beamwidth of an antenna depends upon

    6. A.
    shape of radiation pattern
    B.
    dimensions
    C.
    wavelength
    D.
    all of the above

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  6. Tropospheric mode of propagation is used in

    7. A.
    UHF
    B.
    VLF
    C.
    MF
    D.
    HF

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  7. The skip distance is

    8. A.
    same for each layer
    B.
    independent of frequency
    C.
    independent of the state of ionisation
    D.
    independent of transmitted power

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  8. Polystyrene has a relative permittivity of 2.7. If the wave is incident at an angle θi of 30° from air into polystyrene, the angle of transmission will be nearly

    9. A.
    0.2°
    B.
    2°
    C.
    18°
    D.
    48°

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  9. The radiation pattern of helical antenna (axial mode) is represented by

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  10. Antenna aperture efficiency is given by

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