What is the difference between line-of-sight and slant range in radar systems?

• A. Line-of-sight is the horizontal distance; slant range accounts for altitude difference.
• B. Line-of-sight includes altitude; slant range is only horizontal.
• C. Line-of-sight is the distance to the horizon; slant range is the line of sight plus curvature.
• D. Line-of-sight is vertical distance; slant range is diagonal distance along ground.

Answer: (A)

In radar geometry, you distinguish between the horizontal ground distance and the actual 3D distance the radar signal travels. The line-of-sight distance often refers to the horizontal (ground) range between the radar and the target as projected onto the Earth’s surface. The slant range is the true straight-line distance through space from the radar to the target, which includes the vertical separation (altitude difference). You can think of it like a right triangle: the horizontal distance is one leg, the altitude is the other leg, and the slant range is the hypotenuse. So slant range = sqrt(horizontal distance^2 + altitude^2). That’s why the slant range accounts for height differences while the line-of-sight, in this context, is the horizontal distance on the ground. Other choices mix up these ideas (for example, suggesting line-of-sight is the distance to the horizon or that curvature must be added) and don’t reflect how the vertical component is included in the actual radar path.