Why S-band RADAR is not preferred in merchant ships?
1. Detection of small objects nearby is poor compared to that of the X band.
This is due to interference caused by energy being reflected off the sea surface.
The height of targets needs to three times more for S-band RADAR to detect than if they were detected by 3cm RADAR.
2. To have the same HBW as an X-band RADAR, the horizontal size of the scanner of an S-band RADAR would have to be increased threefold.
In view of the above points, the X-band is generally preferred for the RADAR of a merchant ship.