Page:Electronics Technician - Volume 7 - Antennas and Wave Propagation - NAVEDTRA 14092.pdf/120

 3-52. For a waveguide to be terminated with a resistive load, that load must be matched to which of the following properties of the waveguide?
 * 1) The bandwidth
 * 2) The frequency
 * 3) The inductance
 * 4) The characteristic impedance

3-53. A resistive device with the sole purpose of absorbing all the energy in a waveguide without causing reflections is a/an
 * 1) iris
 * 2) horn
 * 3) antenna
 * 4) dummy load

3-54. A resistive load most often dissipates energy in which of the following forms?
 * 1) Heat
 * 2) Light
 * 3) Magnetic
 * 4) Electrical

3-55. Reflections will be caused by an abrupt change in which of the following waveguide's physical characteristics?
 * 1) Size and shape only
 * 2) Size and dielectric material only
 * 3) Dielectric material and shape only
 * 4) Size, shape, and dielectric material

3-56. A waveguide bend that in the E and H plane must be greater than. two wavelengths to prevent
 * 1) cracking
 * 2) reflections
 * 3) energy gaps
 * 4) electrolysis

3-57. A flexible waveguide is used in short sections because of the power-loss disadvantages. What is the cause of this power loss?
 * 1) Walls are not smooth
 * 2) E and H fields are not perpendicular
 * 3) Cannot be terminated in its characteristic impedance
 * 4) Wall size cannot be kept consistent

3-58. The choke joint is used for what purpose in a waveguide?
 * 1) To reduce standing waves
 * 2) To restrict the volume of electron flow
 * 3) To prevent the field from rotating
 * 4) To provide a joint that can be disassembled during maintenance

3-59. A circular waveguide is normally used in a rotating joint because rotating a rectangular waveguide would cause which of the following unwanted conditions?
 * 1) Oscillation
 * 2) Large power
 * 3) Decrease in bandwidth
 * 4) Field—pattern distortion

3-60. In your waveguide inspection, you should be alert for which of the following problems?
 * 1) Corrosion
 * 2) Damaged surfaces
 * 3) Improperly sealed joints
 * 4) Each of the above

3-61. What type of corrosion occurs when dissimilar metals are in contact with each other? 16
 * 1) Contact
 * 2) Metallic
 * 3) Electrical
 * 4) Electrolytic