SAM Electronics GmbH NG3028X25KW Manual Do Utilizador

ED 3038 G 232 / 01 (2002-06) 

b_r1_e33.fm / 21.06.02

Disturbances of the radar video are caused by
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meteorological processes,

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reflections from the sea surface,

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radar signals from other transmitters,

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false echo displays,

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sectors of reduced radar visibility,

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superrefraction and subrefraction.

The influence of meteorological phenomena such as fog, rain, snow or hail on the radar video increases
with the size of the droplets in relation to the radar wavelength, and with the density of the droplets. The
shorter-wave X-band radar (with a wavelength of 3 cm) is therefore generally impaired more severely by
meteorological influences than is the longer-wave S-band radar (10 cm wavelength).

Even in the X-band radar, fog causes practically no disturbances, whereas precipitations with larger drop-
lets attenuate the transmitted radar pulses and thus weaken to a greater or lesser extent the display of
targets situated behind extensive areas of precipitation. Furthermore, throughout their entire extent, rain,
snow and hail reflect part of the transmitted energy and produce echoes in the form of milky areas in the
radar video (backscatter).

Because of the very different signal structures of useful targets and rain areas, rain clutter can be notice-
ably reduced by the rain clutter suppression function.

Two adjacent targets merge to 
form one radar echo (azimuthal 
distortion)

Radial distortion

Azimuthal distortion

Radar video

Actual size of the target

Two targets behind one 
another merge to form one 
radar echo (radial distortion)

Width of the beam radi-
ated by the antenna

A spit of land is displayed wider

An entrance is 
displayed narrower or 
not at all

Land contour

Radar video