Subelement E: Antenna Systems- 5 Key Topics – 5 Exam Questions— Topic 39: Antenna Systems
Question 8-39E6
Element 8 (RADAR)What is the most common type of RADAR antenna used aboard commercial maritime vessels?
Explanation
Slotted waveguide arrays are the most common RADAR antenna on commercial maritime vessels due to their inherent advantages for surface navigation. This antenna type naturally produces a fan-shaped beam: very narrow horizontally for excellent azimuth resolution (distinguishing closely spaced targets) and wide vertically. The wide vertical beam compensates for the vessel's pitch and roll, ensuring targets remain within the beam despite sea conditions. They also offer good gain and horizontal polarization, ideal for detecting other ships and buoys on the water.
Parabolic (A) and truncated parabolic (B) antennas, while capable of narrow beams, can struggle with maintaining vertical coverage during vessel motion without complex stabilization, making them less practical for general navigation. Multi-element Yagi arrays (D) are typically used for much lower frequencies (VHF/UHF) and are not suitable for the microwave frequencies (X-band, S-band) used by marine navigation RADAR, nor do they offer the required beam shape or gain.
Related Questions
8-39E4 The center of the transmitted lobe from a slotted waveguide array is:8-39E5 How does antenna length affect the horizontal beamwidth of the transmitted signal?8-3A1 Frequencies generally used for marine RADAR are in the ___ part of the radio spectrum.8-3A2 Practical RADAR operation requires the use of microwave frequencies so that:8-3A3 An S-band RADAR operates in which frequency band?