BendixKing IN-862A System RDR-2100 - Manual (Page 21)

ALTITUDE RING (RANGE RING)
Not all radar transmitted energy is contained in the main beam radiation
pattern. Some of the energy is radiated in the side lobe pattern. The
characteristics of some radomes and/or nose caps can cause detrimental
side lobe radiation. Should this occur, the side lobe can be radiated down
toward the earth and the reflected energy received by the radar may be
displayed on the indicator as a narrow ring of video. When the indicator is
on the 10 or 20 nm range, this can be seen at a distance corresponding to
the altitude, typically one mile per 6000 feet. During “Wx” operation, when
this phenomenon occurs, no appreciable degradation of the radar to
depict weather exists. This phenomenon is largely dependent upon the
shape and physical condition of the radome or nose cap on the aircraft.
Effective Date: 9/98 RDR 2100 Pilot's Guide: Rev 1
17
Theory of Operation
RDR 2100 PG 3/12/07 3:45 PM Page 17