What does "antenna front-to-back ratio" mean in reference to a Yagi antenna?

The front-to-back ratio of a directional antenna, like a Yagi, describes its ability to direct energy forward rather than backward. It is calculated by comparing the power radiated in the primary forward direction to the power radiated exactly 180 degrees in the opposite, or backward, direction. This metric is crucial for minimizing interference from unwanted signals behind the antenna. The distractors incorrectly refer to physical dimensions (like element spacing or length) or the power levels of individual elements rather than the overall radiated power pattern of the entire antenna system.