Icom MR-1000RTM, MR-1000TTM, EX-2714 Basic Radar Theory, Side-lobe echoes, Indirect echoes

BASIC RADAR THEORY 8

Radar uses a form of electromagnetic radiation, which like light, can be reflected. Because of this property, some objects may cause false echoes on the screen where in fact no targets actually exist.

These echoes may appear if a large vessel, bridge, or tank is in proximity. Operators should be familiar with the ef- fects of these phenomena. In some cases, echoes can be reduced.

■Side-lobe echoes

Radiation can escape on each side of the beam inside the lobes. If a target reflects this radiation, it will be dis- played on the screen as an echo.

Main beam

Side lobes

Side-lobe echoes usually occur at short ranges and as a result of large (strongly reflective) targets. They can

be reduced	with proper	adjustment of the
[SEA]/[	] control.
See p. 10 for the [SEA]/[		] control.

True echo

False echoes

■Indirect echoes

Indirect echoes may be returned from either a passing ship, or returned from a reflecting surface, such as a mast on your own ship.

Target

Scanner

Mast or similar obstruction

Target

Own ship

An indirect echo from a reflecting surface will appear on a different bearing from the direct (true) echo, but the distance will be approximately the same for both.

True echo

False echo

True echo

Bridge

Indirect echo

An echo is reflected at this point.

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