Page:Electronics Technician - Volume 7 - Antennas and Wave Propagation - NAVEDTRA 14092.pdf/121

 3-62. Internal arcing in a waveguide is usually a symptom of which of the following conditions?
 * 1) Change in mode
 * 2) Electrolysis at a joint
 * 3) Moisture in the waveguide
 * 4) Gradual change in frequency

3-63. What is the primary purpose of a directional coupler?
 * 1) To sample the energy in a waveguide
 * 2) To change the phase of the energy in the waveguide
 * 3) To change the direction of energy travel in the waveguide
 * 4) To allow energy in the waveguide to travel in one direction only

3-64. What is the electrical distance between. the two holes in a simple directional coupler?
 * 1) 1/8 wavelength
 * 2) 1/4 wavelength
 * 3) 1/2 wavelength
 * 4) 3/4 wavelength

3-65. Of the following characteristics, which is NOT required for a device to be considered a resonant cavity?
 * 1) Be enclosed by conducting walls
 * 2) Possess resonant properties
 * 3) Contain oscillating electromagnetic fields
 * 4) Be round or elliptical in shape

3-66. What property gives a resonant cavity a narrow bandpass and allows very accurate tuning?
 * 1) Low Q
 * 2) High Q
 * 3) Inductive reactance
 * 4) Capacitive reactance

3-67. What factor(s) determine(s) the primary frequency of a resonant cavity?
 * 1) Size only
 * 2) Shape only
 * 3) Size and shape
 * 4) Q of the cavity

3-68. Tuning is the process of changing what property of a resonant cavity?
 * 1) The Q
 * 2) The power
 * 3) The cutoff frequency
 * 4) The resonant frequency

3-69. What are the two basic types of waveguide T junctions?
 * 1) H and T
 * 2) H and E
 * 3) Hybrid Ring and magic T
 * 4) Q and magic T

3-70. A waveguide junction in which the arm area extends from the main waveguide in the same direction as the electric field is an example of what type junction?
 * 1) E-type T
 * 2) H-type T
 * 3) H-type T junction
 * 4) H-type junction

3-71. Low power handling capabilities and internal power losses are the primary disadvantages of which of the following junctions?
 * 1) Magic T
 * 2) Rat race
 * 3) Duplexer
 * 4) Hybrid ring

3-72. The hybrid ring is usually used as what type of device in radar systems? 17
 * 1) Mixer
 * 2) Detector
 * 3) Duplexer
 * 4) Impedance matcher