Editing Insertion loss (section)

==Electronic filters==

Insertion loss is a [[figure of merit]] for an [[electronic filter]] and this data is generally specified with a filter.  Insertion loss is defined as a ratio of the signal level in a test configuration without the filter installed (<math>\left\vert V_1 \right\vert</math>) to the signal level with the filter installed  (<math>\left\vert V_2 \right\vert</math>).  This ratio is described in decibels by the following equation:

:<math>\mbox{Insertion loss (dB)} = 10 \log_{10} {\frac{ \left\vert V_1 \right\vert ^2 }{ \left\vert V_2 \right\vert ^2 }} = 20 \log_{10} { \frac{\left\vert V_1 \right\vert}{\left\vert V_2 \right\vert}}</math>

For passive filters, <math>\left\vert V_2 \right\vert</math> will be smaller than <math>\left\vert V_1 \right\vert</math>. In this case, the insertion loss is positive and measures how much smaller the signal is after adding the filter.