Question 3-93O4

Shipboard RADAR systems require highly directional antennas capable of producing a narrow, fan-shaped beam to accurately detect targets and determine their bearing. A **slotted array** antenna consists of an array of slots cut into a waveguide or metal surface. This design inherently provides high gain and excellent control over the beam shape, allowing for the precise, narrow horizontal beam (for good bearing resolution) and broader vertical beam (to account for ship pitch and roll) characteristic of marine radar. Its robust, flat construction is also well-suited for the harsh marine environment and allows for efficient rotation. **Dipoles** and **Vertical Marconi** antennas are typically omnidirectional or have broad patterns, lacking the high gain and narrow beamwidth essential for radar accuracy and range. **Stacked Yagi** antennas are directional but are more commonly used for lower frequency communications and are generally less suitable for the very high frequencies and precise beamforming required by shipboard radar, especially concerning mechanical stability for continuous rotation.