Which precision radar system uses continuous rotation of a pencil beam around the aircraft and uses the phase of the return signal modulation to maintain track in both azimuth and elevation?

Which precision radar system uses continuous rotation of a pencil beam around the aircraft and uses the phase of the return signal modulation to maintain track in both azimuth and elevation?

• A. Circular
• B. Monopulse scan
• C. Multipathing
• D. Conical Scan

Answer: (D)

Conical scanning relies on a pencil beam that continuously sweeps around the target, tracing a cone about the line of sight. As the beam rotates, the target’s return strength and the phase of the modulated signal vary in a predictable way. If the target is off center, the modulation phase shifts in a way that indicates which direction the beam is misaligned in both azimuth and elevation. The tracking loop uses that phase information to generate error signals for two axes, allowing the antenna to be steered back toward boresight and keep the target locked. This approach is different from monopulse, which uses multiple fixed beams to compute angular errors directly, without rotating the beam. It’s also distinct from circular scanning, which isn’t focused on extracting two-axis phase error for tracking in the same way, and from multipathing, which is about unintended multiple signal paths rather than a tracking method.

Conical scanning relies on a pencil beam that continuously sweeps around the target, tracing a cone about the line of sight. As the beam rotates, the target’s return strength and the phase of the modulated signal vary in a predictable way. If the target is off center, the modulation phase shifts in a way that indicates which direction the beam is misaligned in both azimuth and elevation. The tracking loop uses that phase information to generate error signals for two axes, allowing the antenna to be steered back toward boresight and keep the target locked.

This approach is different from monopulse, which uses multiple fixed beams to compute angular errors directly, without rotating the beam. It’s also distinct from circular scanning, which isn’t focused on extracting two-axis phase error for tracking in the same way, and from multipathing, which is about unintended multiple signal paths rather than a tracking method.