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ECE :: Electromagnetic Field Thoery

  1. Which of the following wave remains unaffected during day and night?

  2. A.
    Tropospheric wave
    B.
    Sky wave
    C.
    Ground wave
    D.
    None of the above

  3. A microwave link uses only line-of-sight propagation.

  4. A.
    True
    B.
    False

  5. The phase velocity of an EM wave propagating in a hollow metallic rectangular waveguide in the TE10 mode is

  6. A.
    equal to its group velocity
    B.
    less than the velocity of light in free space
    C.
    equal to the velocity of light in free space
    D.
    greater than the velocity of light in free space

  7. The electric field of an EM wave propagating in the z direction given by

    The wave is

  8. A.
    linearly polarized in z direction
    B.
    elliptically polarized
    C.
    left hand circularly polarized
    D.
    right hand circularly polarized

  9. Which of the following waves do not exist in waveguides?

  10. A.
    TE waves
    B.
    TM waves
    C.
    TE and TM waves
    D.
    TEM waves

  11. The bidirectional pattern of a broadside array can be converted into unidirectional by

  12. A.
    maintaining the distance of λ/4 between the elements
    B.
    maintaining the distance of λ/2 between the elements
    C.
    installing an identical array behind the main array at distance λ/4 and exciting it by current leading in phase by 90°
    D.
    installing an identical array behind the main array at distance λ/2 and exciting it by current leading in phase by 120°

  13. VLF waves are used for communication system because

  14. A.
    of low power requirement
    B.
    they are least prone to distortion
    C.
    they penetrate the ionosphere easily
    D.
    the transmitting antennas are of convenient size

  15. The radiation pattern of two element collinear array is represent in