Appendix
TM106101(8/01)
RDR-1600 Pilot’s Guide
A-1
APPENDIX
SAFE DISTANCE DETERMINATION
The following information can be used in establishing a minimum safe dis-
tance from the antenna for personnel near an operating airborne weather
radar.
NEAR FIELD/FAR FIELD INTERSECTION
The distance to the near field/far field intersection can be computed by:
Ri =
G
λ
8
π
where Ri=intersection distance from the antenna (in meters)
= Wave length (in meters)
= Antenna gain
DISTANCE TO 1 MW/CM
2
SAFE LIMIT
For a far field power density of 1 mw/cm
2
, the distance (in meters) from
the antenna may be calculated by:
where Rs=the minimum safe distance in meters.
P = Transmitted average power in watts.
G = Antenna gain
PROCEDURES
The above formulas may be used to determine the minimum safe distance.
In either case, the following procedures apply:
a. Determine the distance (Ri) to the near field/far field intersection (para-
graph 1)
b. Determine the distance (Rs) to 1 mw/cm
2
power density
c. If the distance (Rs) determined in item b is less than (Ri) found in item a,
use distance (Ri) as the minimum safe distance
d. If the distance (Rs) determined in item b is greater than (Ri) found in item
a, use distance (Rs) as the minimum safe distance
π
40
GP
Rs
=
