Front-to-back ratio

In telecommunication, the term front-to-back ratio has the following meanings:

1. Of an antenna, the gain in a specified direction, i.e. , azimuth, usually that of maximum gain, compared to the gain in a direction 180° from the specified azimuth.

Note: Front-to-back ratio is usually expressed in dB.

2. A ratio of parameters used to characterize rectifiers or other devices, in which electrical current, signal strength, resistance, or other parameters, in one direction is compared with that in the opposite direction.

Source: from Federal Standard 1037C and from MIL-STD-188