Page ii
GWX 68 Installation Manual
Preliminary Revision 1
190-00286-01
SAFE DISTANCE DETERMINATION
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
2
. See AC 20-68B
for more information on safe distance determination.
Antenna Size
Safe Distance
10”
9.16 ft
12”
10.8 ft
MAXIMUM PERMISSIBLE EXPOSURE LEVEL (MPEL)
The zone in which the radiation level exceeds the US Government standard of 1 mW/cm
2
, is the semi-
circular area of at least 9.16 ft from the 10” antenna and 10.83 ft from the 12” antenna as indicated in the
illustration below. All personnel must remain outside of this zone. The distance to the MPEL boundary
is calculated upon the basis of each antenna available with the GWX 68 system, rated output power of the
transmitter, and in the non-rotating or boresight position of the antenna (see example calculations above).
With a scanning or rotating beam, the averaged power density at the MPEL boundary is significantly
reduced.
MPEL
Boundary
Radome
Center Line of
Aircraft
10.83 ft for 12” ant
9.16 ft for 10” ant
Antenna
