The Decibel
The basic idea is to represent the ratio
POUT / PIN for any device in terms of a math function that appears naturally in engineering design formulas. The function is the LOG or Logarithm.
We will use the logarithm associated with the decimal numbering system, so
LOG(X) is sometimes written LOG10(X) although this practice will be unnecessary for us.
A LOG value is either +, for a device with a positive gain
or -, for a device with loss, i.e. where POUT < PIN.
