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Bruce in alaska Bruce in alaska is offline
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First recorded activity by BoatBanter: Dec 2007
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Default X-band and S-band Radar

In article ,
Wayne.B wrote:

On Tue, 06 Jan 2009 11:23:34 -0600, Geoff Schultz
wrote:

In an attempt to discuss something related to cruising, can someone explain
the differences between X-band and S-band radar systems? From what I know,
S-band is used on large ships and X-band is used on vessels less than 300
tons.

-- Geoff
www.GeoffSchultz.org


The key difference is that they operate in two completely different
frequency ranges, much like the difference between VHF and UHF
television. X-band is from is from 7 to 12.5 GHz, S-band is at a
lower frequency (longer wavelength) between 2 and 4 GHz.

Because of the shorter wavelength, X band radar can resolve between
smaller objects but usually has less range because of increased signal
attenuation. S band typically has greater range but requires much
larger antennas, too large for the average small to mid size pleasure
boat.


Add to the above, that Marine S-Band Radars are 2.9 - 3.2 Ghz and Marine
X-Band Radar are 9.3 - 9.5 Ghz. S-Band Radars are much more likely to be
blinded by Snow and Heavy Rain that X-Band Radars. S-Band Radars require
Antennas that are MUCH Larger than X-Band Radars due to the Frequencies
involved. S-Band Radars predate X-Band Radars in production because
Magnetrons were easier to build, for the Lower Frequencies. Most Marine
WWII Radars were S-Band, including the venerable SO Radar fitted to the
PT Boats, who's antenna looks like an upside down R2D2 on a Mast.

--
Bruce in alaska
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