Page:Electronics Technician - Volume 7 - Antennas and Wave Propagation - NAVEDTRA 14092.pdf/114

 2-47. The elements of a broadside array are spaced one—half wavelength apart and are spaced how many wavelengths away from the reflector?
 * 1) One—eighth
 * 2) One—quarter
 * 3) One—half
 * 4) Three—quarter

2-48. What is the advantage, if any, to offsetting a feedhorn radiator for a parabolic dish?
 * 1) A broader beam angle
 * 2) The elimination of shadows
 * 3) A narrower beam angle
 * 4) No advantage

2-49. What is the range in nautical miles of the AN/GPN-27 radar?
 * 55
 * 75
 * 105
 * 155

2-50. What is the purpose of the jackscrew on the AS-3263/SPS-49(V) antenna?
 * 1) To adjust the beam width
 * 2) To vary the antenna feed horn focal distance
 * 3) To adjust the beam elevation angle
 * 4) To lockdown the antenna for PM

2-51. The OE-172/SPS-55 antenna normally operates in the linearly polarized mode, for what reason. would you use the circular polarized mode?
 * 1) To compensate for the ships pitch and roll
 * 2) To prevent jamming
 * 3) To reduce return echoes from precipitation
 * 4) To achieve over the horizon coverage

2-52. Which of the following is NOT a mode of operation. for the AN/SPN-35A radar set?
 * 1) Final
 * 2) Dual
 * 3) Surveillance
 * 4) Simultaneous

2-53. The two primary safety concerns associated with rf fields are rf burns and injuries caused by dielectric heating.
 * T
 * F

2-54. When a person. is standing in an rf field, power in excess of what level will cause a noticeable rise in body temperature?
 * 1) 5 milliwatts
 * 2) 10 milliwatts
 * 3) 15 milliwatts
 * 4) 20 milliwatts

2-55. When working aloft, what safety precaution(s) must be followed? 10
 * 1) Tag out the antenna at the switchboard to prevent it from becoming operational
 * 2) Secure motor safety switches for rotating antennas
 * 3) Wear the proper oxygen breathing apparatus when working near a stack
 * 4) All the above