Anritsu RA77OUA, Инструкция по эксплуатации

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Side-lobe Echoes
. The beam radiated from a radar antenna is composed
of a main beam and side-lobe beams. Since the energy
levels of side lobes are usually low, false echoes from
the side lobes can be produced by highly reflective
targets at short range (Fig. Side lobe echoes
usually appear as a series of echoes forming a broken
arc. These false echoes are eliminated by slightly
(Note: This echo is similar to virtual or ghost
'increasing
the
STC effect.
echoes.
Beam
Fig.
3-7
Arc of False Echoes caused by Side Lobe Beams
Echoes Produced by Targets at Lonq Ranges Due to the
Duct Phenomenon
Depending on the atmospheric conditions, a
wave duct may above the sea surface. In such cases,
radiowaves can be trapped in the duct, travelling in an
unusual way over unexpectedly long distances. Targets
beyond maximum detectable range may appear as echoes on
the screen as if they are nearer than their true ranges.
This phenomenon is attributable to the fact that an echo
signal from a long distance target is delayed beyond the
repetition period
s o
as to be displayed as
an
echo in the
succeeding period. However,
if
the range is changed
by
pressing the RANGE key, the echo can be
judged false.
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