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Nobeltec InSight Radar (IR2)
Operations Manual
Ducting
If air layers having a different temperature or different atmospheric pressures are
produced alternately in the altitudes, a distant target exceeding the visible range
of the radar is detectable. This phenomenon is caused when air layers having a
different temperature contact each other. The radio waves are not refracted, but
reflected on the boundary where the two layers differ. As a result, radio waves can
be propagated farther that the curvature of the earth. The passage where the radio
waves travel is called a Duct. The abnormal propagation of radio waves through this
duct is called ducting.
Minimum Detectable Range
The minimum distance that the radar can detect a target is called the Minimum
Detectable Range. This minimum range varies depending on radar factors such as
transmission pulse width, RF leakage time and height of transceiver. The following
section describes the factors that affect the Minimum Detectable Range.
Height of Transceiver
Height of the transceiver affects the short range target detection. If the transceiver
is mounted at a relatively high level from the sea surface, the radar wave may
skip closer targets causing the radar to fail in detection of these closer targets. The
radar’s Vertical Beam Width is also involved, as shown in the figure above. Wider
beam results in better short range detection, however it also shortens the detectable
range.
Understanding Radar
