Front-to-back ratio

Related wiki pages: Antennas, Gain, Propagation, SWR

Front-to-back ratio (FBR) is a measure of how effectively a directional antennas, eg Yagi, Log Periodic (LPDA), Dish or Parabola projects RF energy in the desired direction.

It is calculated as the ratio of the maximum directivity of the antenna to the directivity in the opposite direction.

To quantify FBR, a radiation pattern plot is drawn.

FBR = maximum radiation (dB) in the forward direction - maximum radiation (dB) at $$ 180^0 $$

FBR is of course meaningless for omnidirectional antennas.