X-band versus S-band radars

Simply put, they differ in frequency. The majority of marine radars operate on X-band.  X-band is widely used because of the ability to utilize smaller antennas that fit on most boats and to provide better target resolution. S-band radars are often used for specialized applications, such as seeing through heavy weather or precipitation and for long-range bird detection. S-band antennas are larger. The smallest Furuno S-band antenna is 9 feet long and can be as long as 12 feet.