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Electrical Engineering Objective Questions { Electromagnetism }

71. Power gain GP of an antenna in a given direction is the ratio of
A. radiation intensity in that direction to the average radiated power
B. radiation intensity in that direction to the total input radiated power
C. average power to maximum power
D. peak power to rms power

72. The effect of ground on radiation pattern of an antenna is
A. to produce more number of nulls.
B. to cause concellation of radiation along the ground
C. both and above
D. to change its effective wavelength

73. Yagi antenna has
A. one driven element and one reflector element
B. one driven element and one director element
C. only a folded dipole
D. driven element, reflector element and several director elements

74. A nonresonant antenna is
A. Yagi antenna
B. folded dipok.
C. rhombic antenna
D. log periodic antenna

75. An isotropic radiator is one which short circuited impedance is to Yagi antenna is
A. folded dipole
B. good bandwidth
C. parasitic element
D. low cost

76. The term which does not apply range. It is best to use
A. a balun transformer
B. a single stub of adjustable position
C. a double stub
D. broad-band directional coupler

77. Antenna reciprocity is used in
A. radio broadcast
B. TV broadcast
C. aircraft instrumentation
D. multiplex tele metry

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