31 4-66. The principal disadvantage of the rhombic antenna is its 1. poor directivity2. large antenna site 3. low antenna voltage 4. high-frequency inefficiency 4-67. The unidirectional radiation pattern of the rhombic antenna is caused by which of the following antenna characteristics? 1. Size 2. Shape 3. Termination resistance4. Frequency of the input energy 4-68. Horizontal half-wave antennas mounted at right angles to each other in the same horizontal plane make up which of the following antennas? 1. Rhombic 2. Flat-top 3. Turnstile 4. Ground-plane 4-69. The most common means of obtaining a low-radiation angle from a vertical quarter-wave antenna is by what procedure? 1. Decreasing power 2. Increasing frequency 3. Adding a ground plane 4. Rotating the antenna to a horizontal plane 4-70. A corner reflector antenna is used for which of the following purposes? 1. To decrease frequency range 2. To increase frequency range 3. To produce a unidirectional pattern 4. To produce an omnidirectional pattern 4-71. If a corner-reflector antenna is horizontally polarized, its radiationpattern will take on what shape? 1. A narrow beam in the horizontal plane 2. A narrow beam in the vertical plane 3. A beam similar to a half-wave dipole in the horizontal plane 4. A beam similar to a half-wave dipole with a reflector in the vertical plane 4-72. When radio or radar antennas are energized by transmitters, you must not go aloft until which of the following requirements are met? 1. A safety harness has been issued to you 2. All transmitters are secured and tagged 3. A working aloft "chit" has been filled out and signed by proper authority 4. Each of the above
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