Which scan type sweeps through a sector in only one direction?

The scan type that sweeps through a sector in only one direction is the uni-directional scan. This type of scan focuses on moving the sensor or system in a single direction, allowing for thorough monitoring of that specific area without oscillating back and forth. This method is particularly useful in applications where constant surveillance in one direction is needed, such as tracking a moving target or monitoring a particular sector for signals.

In contrast, conical scans involve moving in a circular or conical pattern, which sweeps through an area in a more comprehensive manner. Agile beam scans are designed to rapidly switch between targets or sectors but do so in a non-linear fashion, allowing for flexibility in scanning. Steady scans maintain a constant position but typically sweep back and forth in either a horizontal or vertical direction rather than moving solely in one direction. Thus, to accurately meet the criteria of sweeping through a sector in just one direction, the uni-directional scan is the appropriate choice.