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36.
Select the absolute units of power. (Choose all that apply.)
- A.Watt
- B.Milliwatt
- C.Decibel
- D.dBm
- E.Bel
- Answer & Explanation
- Report
Answer : [A, B, D]
Explanation :
Explanation :
| Watts, milliwatts, and dBms are all absolute power measurements. One watt is equal to 1 ampere (amp) of current flowing at 1 volt. A milliwatt is 1/1,000 of 1 watt. dBm is decibels relative to 1 milliwatt. |
37.
Select the units of comparison (relative). (Choose all that apply.)
- A.dBm
- B.dBi
- C.Decibel
- D.dBd
- E.Bel
- Answer & Explanation
- Report
Answer : [B, C, D, E]
Explanation :
Explanation :
| The unit of measurement known as a bel is a relative expression and a measurement of change in power. A decibel (dB) is equal to one-tenth of a bel. Antenna gain measurements of dBi and dBd are relative measurements. dBi is defined as decibels referenced to an isotropic radiator. dBd is defined as decibels referenced to a dipole. |
38.
2 dBd is equal to how many dBi?
- A.5 dBi
- B.4.41 dBi
- C.4.14 dBi
- D.The value cannot be calculated.
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| To convert any dBd value to dBi, simply add 2.14 to the dBd value. |
39.
23 dBm is equal to how many mW?
- A.200 mW
- B.14 mW
- C.20 mW
- D.23 mW
- E.400 mW
- Answer & Explanation
- Report
Answer : [A]
Explanation :
Explanation :
| To convert to mW, first calculate how many 10s and 3s are needed to add up to 23, which is 0 + 10 + 10 + 3. To calculate the mW, you must multiply 1 × 10 × 10 × 2, which calculates to 200 mW. The file ReviewQuestion9.ppt, available for download from www.sybex.com/go/cwna4e, shows the process in detail. |
40.
A wireless bridge is configured to transmit at 100 mW. The antenna cable and connectors
produce a 3 dB loss and are connected to a 16 dBi antenna. What is the EIRP?
- A.20 mW
- B.30 dBm
- C.2,000 mW
- D.36 dBm
- E.8 W
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| To reach 100 mW, you can use 10s and 2s and multiplication and division. Multiplying by two 10s will accomplish this. This means that on the dBm side, you must add two 10s, which equals 20 dBm. Then subtract the 3 dB of cable loss for a dBm of 17. Because you subtracted 3 from the dBm side, you must divide the 100 mW by 2, giving you a value of 50 mW. Now add in the 16 dBi by adding a 10 and two 3s to the dBm column, giving a total dBm of 33. Because you added a 10 and two 3s, you must multiply the mW column by 10 and two 2s, giving a total of 2,000 mW, or 2 W. Since the cable and connector loss is 3 dB and the antenna gain is 16 dBi, you can add the two together for a cumulative gain of 13 dB; then apply that gain to the 100 mW transmit signal to calculate an EIRP of 2,000 mW, or 2 W. The file ReviewQuestion10.ppt, available for download from www.sybex.com/go/cwna4e, shows the process in detail. |
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