greater than the output power so you have a power loss. To find the power loss, you divide .001 by .000001
which equals 1.000. In Table 3-4, this corresponds to 30 dB. So your answer is -30 dB.
Table 3-4. Formulas.
b. Example 2. Suppose you know the dB gain is 40 dB. The ratio of the output power to the input power
is found by referring to Table 3-4, where 40 dB corresponds to a ratio of 10,000. If you know the input power
is .001 watt, you can find the output power by multiplication: .001 watt X 10,000 = 10 watts.
Figure 3-11. Circuit showing power loss.
7. The decibel milliwatt (dBm) represents a reference level.
a. Before explaining the dBm, let's first find out what is meant by a reference level. The simplest way to
explain it is to use an everyday example.
b. Suppose you had 0 in a savings account at the beginning of a year. This 0 could act as a
reference level. You could actually plot your savings account for the whole year on a graph as shown in Figure
3-12. You'd put 0 in the center of the vertical axis. And then place plus signs above 0 and minus signs
below 0. Then as the
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