Why do video amplifiers in pulse RADAR receivers need broad bandwidth?

The correct choice is focused on managing the characteristics of radar signals. Video amplifiers in pulse RADAR receivers are specifically designed to handle the signal's amplitude and temporal properties. Weak pulses must be amplified vigorously to ensure that the desired signal can be detected against background noise and other interference.

In radar applications, the signals can vary significantly in strength, and when weak pulses are received, they often require amplification to make them usable for further signal processing and detection. Broad bandwidth is essential for these amplifiers because it allows them to accurately process a range of frequencies within the pulse, ensuring that the integrity of the signal is maintained, even when it is weak. Therefore, a video amplifier with broad bandwidth is critical to enhance weak pulses effectively so they can be identified and analyzed.

While the other options provide some relevant context about radar signals—such as the management of pulse shape or the operational efficiency at higher pulse repetition frequencies—they do not directly capture the primary function of video amplifiers in relation to dealing with weak signals, which is a fundamental reason for the necessity of broad bandwidth.