Question:
Radio Frequency Loss and Gain
Calculate radio frequency gain and loss
1. Using Table 3-3 as a reference, what is the dB of 1 watt of power?
2. A wireless device has output of 200 mW. It is connected to a cable with a 9 dBi gain and a 6 dB loss. What is the EIRP?
Imagine you are the network administrator of a WLAN. Give an example of how knowing the 10's and 3's Rules of RF Math can help you on the job.
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Rule
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Explanation
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Percentage of Power Lost/Gained
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Current Power Level
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Example
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-3 dB
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Half the watt value
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50% lost
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Half of original
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100 mW - 3dB = 50 mW
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+3 dB
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Double the watt value
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100% gained
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Double the original
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10 mW + 3dB = 20 mW
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-10 dB
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Decrease watt value to one tenth of original
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90% lost
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One-tenth of original
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300 mW -10 dB = 30 mW
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+10 dB
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Increase the watt value by ten-fold
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1,000% gained
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Ten times the original
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10 mW = 10 dB = 100 mW
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