78. AV-antenna consists of
A. two wires with an apex angle of 45?
B. two (X/2) long wires with an apex angle of 45?
C. two (V4) long wires with an apex angle of 45?
D. none of these

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79. One of the following is an non-resonant antenni
A. The folded dipole
B. The endfire array
C. The broadside array
D. The rhombic antenna

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80. One of the following antenna types is best excited from a waveguide
A. Horn antenna
B. Helical antenna
C. Biconical antenna
D. Log-periodic antenna

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81. Top loading is used with antennas to
A. increase the effective height
B. reduce the effective height
C. increase the bandwidth
D. increase the input capacitance

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82. A helical antenna is used for satellite tracking because of its
A. large bandwidth
B. large gain
C. circular polarization
D. maneuverability

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83. The antenna of Fig. 13.2(a) produces
A. horizontal polarised waves
B. circularly polarised waves
C. vertically polarised waves
D. none of these

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84. Fig. 13.3 shows the power densit radiation pattern of a certain antenna. The beamwidth of the antenna is
A.an upper bandwidth
B. a lower bandwidth
C. a flat response
D. none of these

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