Microware Power Measurement Units
The unit of power is watt (W). One watt is equivalent to 1000 milliwatts.
Relative power is most widely used and expressed in decibels (dBs). Relative power is commonly denoted in dbm. dbm stands for db milliwatt. The requirement for logorithmic scale is due to the fact that rf power ranges from very low value for a microwave receiver (of the order of 10-12 w or less) to several kilo watts (10 3) for microware transmitters. Representing the values, and mathematical calculations using linear power measurement units is quite cumbersome with such a large dynamic range.
dBm is defined as below;
1 dBm = 10 log 10(P/1mW);
For example, 1 watt of power is equivalent to:
10 log (103) or 30 dBm.