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ECE :: Electromagnetic Field Thoery

  1. When a particular mode is excited in a waveguide, these appears an extra electric components in the direction of propagation. The resulting mode is

  2. A.
    Transverse electric
    B.
    Transverse magnetic
    C.
    Longitudinal
    D.
    Transverse Electromagnetic

  3. An antenna has a gain of 44 dB. Assuming that the main beam of the antenna is circular in cross-section the beamwidth will be

  4. A.
    0.4456°
    B.
    1.4456°
    C.
    2.4456°
    D.
    3.4456°

  5. The directive gain of an antenna is given by


  6. In cellphone communication base antennas are connected to other base antennas in

  7. A.
    line of sight communication
    B.
    ionospheric propagation
    C.
    ground wave propagation
    D.
    medium wave propagation

  8. The I/P impedance of a long short circuited section of a loss less transmission line is

  9. A.
    zero
    B.
    inductive
    C.
    capacitance
    D.
    infinite

  10. Which of the following relations is correct?

  11. A.
    ∇ . = r
    B.
    ∇ . = r
    C.
    ∇ . = - r
    D.
    ∇ . =

  12. For frequencies upto 1650 kHz __________ antenna is used

  13. A.
    yagi
    B.
    grounded
    C.
    turnstile
    D.
    marconi

  14. Due to which of the following reasons, the ground wave eventually disappears, as one moves away from the transmitter?

  15. A.
    Tilting
    B.
    Loss of line-of-eight conditions
    C.
    Interference from the sky wave
    D.
    Maximum single hop distance limitation

  16. A loop antenna may be of

  17. A.
    square on triangular shape
    B.
    hexagonal shape
    C.
    circular shape
    D.
    any of the above

  18. Velocity of the wave when it passes from air into sphere

  19. A.
    decreases
    B.
    increases
    C.
    same
    D.
    no change