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

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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

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

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

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

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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

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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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