What happens if a radar unit is pointed at a steep angle?

When a radar unit is pointed at a steep angle, it can lead to inaccuracies in speed readings primarily due to what is known as cosine error. Cosine error occurs when the radar beam is not perpendicular to the path of the vehicle being measured. In a typical setup, the radar should ideally be aimed directly at the vehicle's direction of travel to ensure that the full velocity of the vehicle is captured.

If the radar unit is angled steeply, the speed reading taken will represent only a portion of the vehicle's actual speed due to the angle of incidence. This results in an underestimation of the speed because only the component of the vehicle's velocity that is aligned with the radar beam is measured. The steeper the angle, the greater the potential for error, making it crucial to maintain the radar in a position that minimizes these effects. Understanding this concept is vital for anyone involved in speed enforcement using radar technology, as it directly impacts the reliability of their measurements.