50.  Indicate the FALSE statement. The parabolic reflector is
A. omnidirectional antenna
B. pencil beam antenna
C. popularly used antenna is terrestrial line-of-sight communication
D. not a broadcast antenna

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51. An antenna that is circularly polarized is the
A. helical
B. small circular loop
C. parabolic reflector
D. circular horn

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52.  A geostationary satellite
A. is motionless in space (except for its spin)
B. is not really stationary at all but orbits the earth with a 24 hrs period
C. is located at a height of approximately 36,000 km to ensure global coverage
D. appears stationary over the earth's magnetic dipole

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53. The voice channel bandwidth b, according to CCIR recommendation, is ____ kHz.
A.4
B.4.2
C.3.1
D.2.5

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54. A superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency is ___ kHz.
A.750
B.300
C.1650
D.2100

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55. Microwave communication uses
A. long-wave antennas
B. rhombic antennas
C. paraboloidal antennas
D. lobe antennas

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56. A modulating signal of 500 Hz, fed into an FM generator produces a frequancy deviation of 2000 Hz. The modulation index is
A.4
B.2
C.5
D.8

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