Page:Electronics Technician - Volume 7 - Antennas and Wave Propagation - NAVEDTRA 14092.pdf/118

3-31. In practical applications, which of the following dimensions describes the wide dimension of the waveguide at the operating frequency?

1. 0.1 wavelength
2. 0.2 wavelength
3. 0.5 wavelength
4. 0.7 wavelength

3-32. Which of the following fields is/are present in waveguides?

1. E field only
2. H field only
3. E and. H fields
4. Stationary fields

3-33. A difference in potential across a dielectric causes which of the following fields to develop?

1. Electric only
2. Magnetic only
3. Electromagnetic

3-34. H lines have which. of the following distinctive characteristics?

1. They are continuous straight lines
2. They are generated by voltage
3. They form closed loops
4. They form only in the waveguide

3-35. For an electric field to exist at the surface of a conductor, the field must have what angular relationship to the conductor?

1. 0°
2. 30°

3 45° 4 90°

3-36. If the wall of a waveguide is perfectly flat, the angle of reflection is equal to which of the following angles?

1. Cutoff
2. Incidence
3. Refraction
4. Penetration

3-37. The cutoff frequency in a waveguide occurs at exactly what angle of reflection?

1. 10°
2. 30°
3. 45°
4. 90°

3-38. How does the group velocity of an electromagnetic field in a waveguide compare to the velocity of a wavefront through free space?

1. Group velocity is somewhat faster
2. Group velocity is somewhat slower
3. Group velocity is twice that of free velocity
4. Free velocity is twice that of group velocity

3-39. The group velocity of a wavefront in a waveguide may be increased by which of the following actions?

1. Decreasing the frequency of the input energy
2. Increasing the frequency of the input energy
3. Increasing the power of the input energy
4. Decreasing the power of the input energy

3-40. The various field configurations that can exist in a waveguide are referred to as

1. wavefronts
2. modes of operation
3. fields of operation
4. fields of distribution

3-41. The most efficient transfer of energy occurs in a waveguide in what mode?

1. Sine
2. Dominant
3. Transverse
4. Time-phase

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