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ECE :: Electromagnetic Field Thoery

  1. A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls Calculate group velocity for dominant mode.

  2. A.
    1.8 x 108 m/sec
    B.
    5 x 108 m/sec
    C.
    3 x 108 m/sec
    D.
    1.5 x 108 m/sec

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  3. For F1 layer the maximum ionic density is 2.3 x 104 electrons per cc. The critical frequency for this layer will be

  4. A.
    1.36 MHz
    B.
    13.6 MHz
    C.
    136 MHz
    D.
    1360 MHz

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  5. Which one of the following does represents the electric field lines for the TE02 mode in the cross section of a hollow rectangular metallic waveguide?

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  7. The velocity of electromagnetic wave in a good conductor is

  8. A.
    3 x 108 m/s
    B.
    more than 3 x 108 m/s
    C.
    very low
    D.
    high

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  9. Radiation intensity of a dipole depends strongly on frequency. If at a frequency f, the intensity of radiation is 'I'. Then at a frequency of f/2, the intensity will be

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  11. Consider a 300 Ω, quarter wave long at 1 GHz transmission line as shown in figure. It is connected to a 10 V, 50 Ω source at one end is left open circuited at the other end. The magnitude of the voltage at the open circuit end of the line is

  12. A.
    10 V
    B.
    5 V
    C.
    60 V
    D.
    60/7 volt

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  13. The phase angle corresponding to λ/4 in a standing-wave pattern is

  14. A.
    30°
    B.
    90°
    C.
    135°
    D.
    180°

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  15. A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm.

  16. A.
    49
    B.
    47.33
    C.
    50.33
    D.
    50

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  17. Calculate the directivity of an antenna for θE = 30°, θH = 60

  18. A.
    46
    B.
    23
    C.
    50
    D.
    100

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  19. Most antenna consisting of a 50 meter long vertical conductor operates over a perfectly conducting ground plane. It is base fed at a frequency of 600 kHz. The radiation resistance of the antenna in ohms is

  20. A.
    B.
    C.
    D.
    20p2

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