Home / ECE / Electromagnetic Field Thoery :: section-14

ECE :: Electromagnetic Field Thoery

  1. A square corner reflector is used in

  2. A.

     Radio astronomy

    B.

     Tv broadcast

    C.

     Point to point communication

    D.

     All of the above


  3. In microwave communication links, when fading due to rain attenuation occurs then technique adopted for solving the problem would include

  4. A.

     Antenna replacement and feed correction

    B.

     Amplitude timing and phase correction

    C.

     Polarization shifting and code diversity

    D.

     Path diversity and frequency diversity


  5. The power gain of a half-wave dipole with respect to an isotropic radiator is

  6. A.

     2.15 db

    B.

     3 db

    C.

     4.15 db

    D.

     6 db


  7. MUF is highest in periods of greatest sunspot activity.

  8. A.

     True

    B.

     False


  9. The attenuation in waveguide above to cut off frequency

  10. A.

     Very high

    B.

     Very low

    C.

     Zero

    D.

     Infinite


  11. A waveguide operated below cut off frequency can be used as

  12. A.

     Phase shifter

    B.

     An attenuator

    C.

     An isolator

    D.

     None


  13. The wave in wave guide has

  14. A.

     Group velocity inversely proportional to wavelength

    B.

     Larger frequency than in the free space

    C.

     Diminishing wavelength than in the free space

    D.

     Larger wavelength than in the free space


  15. Radiation intensity in a given direction is the

  16. A.

     Energy radiated per square metre

    B.

     Power radiated per square metre

    C.

     Power radiated per unit solid angle in that direction

    D.

     None of the above


  17. Which of the following impedance inversion is obtained?

  18. A.

     Short-circuited stub

    B.

     A quarter wave line

    C.

     Balun transformer

    D.

     A half wave line


  19. When a conductor moves in the field, so that it makes an angle 8 with the lines of flux, the force F is given as : F = Bl sin2 0.

  20. A.

     Yes

    B.

     No