Now look at Table 3-3 to find the log of 2. The log is .3010 so you have-
dB = 10 x .3010
Table 3-3. Logarithms.
Since you're dealing with a power loss, you use a minus sign to express the final answer:
-3.01 dB or approximately -3 dB
5. Solving the formula for dB gain.
a. Figure 3-10 shows a repeater that amplifies the input power to twice its original value. You see that the
input power to the repeater is 1 mW and the output power is 2 mW. You can find out how much dB gain this
repeater provides by using the formula:
Number of dB = 10 x log P2 (larger power)
P1 (smaller power)
dB = 10 x log 2
1
dB = 10 x log 2
3-31
SS0031
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