What is the primary function of the antenna in a radar speed detection system?

The primary function of the antenna in a radar speed detection system is to transmit and receive radar signals. In this context, the antenna plays a crucial role as it emits radar waves towards moving objects, such as vehicles, and then picks up the reflected signals that bounce back. These received signals are then processed to determine the speed of the moving object based on the Doppler effect, which describes how the frequency of the waves changes as the distance between the source and the observer varies.

The other choices highlight different aspects of the radar speed detection system but do not capture the main role of the antenna. Providing power to the device is handled separately, usually by an internal battery or external power source. Displaying speed readings is the function of the device's output interface, which translates the processed information into readable data for the officer. Collecting data for speed analysis is also an important function, but it is more related to the processing unit than the antenna itself. Thus, the antenna's core responsibility lies in the transmission and reception of radar signals critical for speed measurement.