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ECE :: Electromagnetic Field Thoery

  1. A transmission line is feeding 1 watt of power to a horn antenna having a gain of 10 dB. The antenna is matched to the transmission line. The total power radiated by the horn antenna into the free space is

  2. A.
    10 watts
    B.
    1 watt
    C.
    0.1 watt
    D.
    0.01 watt

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  3. A parallel polarized wave is incident from air into paraffin having relative permittivity 3, the value of its Brewster angle is

  4. A.
    B.
    30°
    C.
    45°
    D.
    60°

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  5. In a conductor which of the following relations hold good?

  6. A.
    ∇ x D = r
    B.
    ∇ . D = r
    C.
    ∇ x D = 0
    D.
    ∇ . D = 0

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  7. The radiation resistance of a λ/16 wire dipole in free space will be nearly

  8. A.
    1 Ω
    B.
    3 Ω
    C.
    13 Ω
    D.
    30 Ω

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  9. Two identical antennas are placed in the θ = p/2 plane as shown in the figure. The elements have equal amplitude excitation with 180° polarity difference, operating of the far-zone resultant electric field strength normalized with that of a single element, both computed for φ = 0, is

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  11. Find the noise factor for an antenna at 27°C with equivalent noise temperature 30°K

  12. A.
    20
    B.
    100
    C.
    300
    D.
    1.1

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  13. The displacement flux density at a point on the surface of a perfect conductor is = 2(ax - 3 az)c/m2 pointing away from the surface. The charge density at that point c/m2 will be

  14. A.
    2
    B.
    - 2
    C.
    4
    D.
    - 4

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  15. Characteristic impedance of a transmission line is 50 Ω. Input impedance of the open circuited line.
    Zoc = 100 + J150 Ω. When transmission line is short circuited, then value of the input impedance will be

  16. A.
    50 Ω
    B.
    100 + J150 Ω
    C.
    7.69 + J11.54Ω
    D.
    7.69 - J11.54 Ω

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