How is directivity defined in radar systems?

Directivity in radar systems refers to how focused the radar beam is. It is a measure of how well the antenna converts input power into radio waves in a specific direction. A highly directive antenna emits a concentrated beam of energy, which allows for improved signal strength in a particular direction and enhances the radar's ability to detect targets within that focused area. This directivity is essential for applications where precision in detecting and tracking objects is critical, such as in weather radar or military applications.

The other options do not accurately capture the essence of directivity. For instance, while the strength of the received signal relates to the overall intensity of the radar return, it does not describe how that signal is directed. The maximum range of the radar pertains to how far the radar can detect targets, rather than how the beam is directed. Finally, the angle of the antenna refers to its physical position, but this does not imply the focus or concentration of the energy that defines directivity.