Operating Distance; Maximum Permissible Exposure Level (Mpel) (Gwx 68) - Garmin GTN 725 Pilot's Manual

A smaller incident angle gives the radar a larger detectable range of operation
and the target display will show a higher intensity. Since more radar energy is
reflected back to the antenna with a low incident angle, the resulting detectable
range is increased for mountainous terrain.
12.3.3

Operating Distance

The following information establishes a minimum safe distance from the
antenna for personnel near an operating airborne weather radar. The minimum
safe distance is based upon the FCC' s exposure limit at 9.3 to 9.5 GHz for general
population/uncontrolled environments which is 1 mW/cm
Circular 20-68B for more information on safe distance determination.
12.3.3.1

Maximum Permissible Exposure Level (MPEL) (GWX 68)

The zone in which the radiation level exceeds the US Government standard
of 1 mW/cm , is the semicircular area of at least 11 feet from the 12 inch antenna
2
as indicated in the illustration below. All personnel must remain outside of this
zone. With a scanning or rotating beam, the averaged power density at the MPEL
boundary is significantly reduced.
12.3.3.2 Maximum Permissible Exposure Level (MPEL) (Other
Radars)
See the appropriate documentation for MPEL.
190-01007-03 Rev. D
Figure 12-47 Angle of Incidence
Garmin GTN 725/750 Pilot's Guide
. See Advisory
2
12-37
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