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ECE Objective Questions { Antenna }

43.  A helical antenna is used for satellite tracking because of its
A. maneuverability
B. good front-to-back ratio
C. broad bandwidth
D. circular polarization

44.  For the same size of antenna dish more gain will be provided at
A. 4 MHz
B. 6 MHz
C. 12 MHz
D. 16 MHz

45.  The attenuation in waveguides near the cut off frequency is
A. zero
B. very low
C. very high
D. infinite

46.  antenna is best excited from a wave guide.
A. Discone
B. Helical
C. Biconical
D. Horn

47. In which of the following fields application of the microwaves is the largest?
A. Cooking
B. Research
C. Industrial heating
D. Communication

48.  Lene antennas used for microwaves are usually made of
A. paraboloid surfaces
B. polystyrene
C. dielectric media having large refreactive index
D. glass of low refractive index

49.  A duplexer is used to
A. connect a receiver and a transmitter to the same antenna
B. connect two transmitters to the same antenna
C. feed more than one receiver from a signal antenna
D. none of the above

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