Now look at Table 3-3 to find the log of 2. The log is .3010 so you have-

dB = 10 x .3010

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