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