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- CWNA-107
56.
To establish a 4-mile point-to-point bridge link in the 2.4 GHz ISM band, what factors
should be taken under consideration? (Choose all that apply.)
- A.Fresnel zone with 40 percent or less blockage
- B.Earth bulge calculations
- C.Minimum of 16 dBi of passive gain
- D.Proper choice of semidirectional antennas
- E.Proper choice of highly directional antennas
- Answer & Explanation
- Report
Answer : [A, D]
Explanation :
Explanation :
| Point-to-point bridge links require a minimum Fresnel zone clearance of 60 percent. Semidirectional antennas such as patch antennas or Yagi antennas are used for short-to-medium-distance bridge links. Highly directional antennas are used for long- distance bridge links. Compensating for earth bulge is not a factor until 7 miles. |
57.
The ratio between the maximum peak voltage and minimum voltage on a line is known as
what?
- A.Signal flux
- B.Return loss
- C.VSWR
- D.Signal incidents
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| Voltage standing wave ratio (VSWR) is the difference between these voltages and is represented as a ratio, |
58.
What are some of the possible negative effects of an impendence mismatch? (Choose all that
apply.)
- A.Voltage reflection
- B.Blockage of the Fresnel zone
- C.Erratic signal strength
- D.Decreased signal amplitude
- E.Amplifier/transmitter failure
- Answer & Explanation
- Report
Answer : [A, C, D, E]
Explanation :
Explanation :
| The reflected voltage caused by an impedance mismatch can result in a decrease in power or amplitude (loss) of the signal that is supposed to be transmitted. If the transmitter is not protected from excessive reflected power or large voltage peaks, it can overheat and fail. Understand that VSWR may cause decreased signal strength, erratic signal strength, or even transmitter failure. |
59.
When determining the mounting height of a long-distance point-to-point antenna, which of
the following needs to be considered? (Choose all that apply.)
- A.Frequency
- B.Distance
- C.Visual line of sight
- D.Earth bulge
- E.Antenna beamwidth
- F.RF line of sight
- Answer & Explanation
- Report
Answer : [A, B, D, F]
Explanation :
Explanation :
| Frequency and distance are needed to determine the Fresnel zone. Visual line of sight is not needed as long as you have RF line of sight. You may not be able to see the antenna because of fog, but the fog will not prevent RF line of sight. Earth bulge will need to be considered. The beamwidth is not needed to determine the height, although it is useful when aiming the antenna. |
60.
Which of the following are true about cables? (Choose all that apply.
- A.They cause impedance on the signal.
- B.They work regardless of the frequency.
- C.Attenuation decreases as frequency increases.
- D.They add loss to the signal.
- Answer & Explanation
- Report
Answer : [A, D]
Explanation :
Explanation :
| Cables must be selected that support the frequency you are using. Attenua- tion actually increases with frequency. |
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