User's Manual

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Revision 7/26/04 Build 51 Page 10 of 10
TRANZEO WIRELESS QUICK START GUIDE
RF Exposure Evaluation
FCC 1.1310 states that the criteria listed in the following table shall be used to evaluate the
environmental impact of human exposure to RF radiation as specified in 1.1307(b)
Frequency Range
(MHZ)
Electric Field
Strength (V/m)
Magnetic Field
Strength (A/M)
Power Density
(mW/cm2)
Average Time
(A) Limits for Occupational/Control Exposures
300-1500 -- -- F/300 6
1500-100,000 -- -- 5 6
(B) Limits for General Population/Uncontrolled Exposures
300-1500 -- -- F/1500 6
1500-100,000 -- -- 1 30
Fries Formula
Fries transmission formula: Pd = (Pout*G)/(4* p*r2) Where
Pd = power density in mW/cm2
Pout = output power to antenna in mW.
G = gain of antenna in the direction of interest relative to an isotropic radiator.
R = the distance between the observation point and the center of the radiator in cm.
Pd is the limit of MPE, 1mW/cm2.
If we know the maximum gain of the antenna and the total power input to the antenna we can calculate the
distance r where the MPE limit is reached.
RF exposure evaluation distance calculation
TR-CPE200-19
Chan Freq
(MHz)
Output Power to
Antenna (dBm)
Output Power to
Antenna (mW)
Max Antenna
Gain (dBi)
Numeric
Antenna Gain
R(cm)
1 2412 21.06 128 19.5 89.1 30.1
6 2437 21.34 136 19.5 89.1 31.1
11 2462 21.74 149 19.5 89.1 32.5
TR-CPE200-15
Chan Freq
(MHz)
Output Power to
Antenna (dBm)
Output Power to
Antenna (mW)
Max Antenna
Gain (dBi)
Numeric
Antenna Gain
R(cm)
1 2412 21.06 128 15.5 35.5 19.0
6 2437 21.34 136 15.5 35.5 19.6
11 2462 21.74 149 15.5 35.5 20.5
As shown above, the minimum distance where the MPE limit is reached is 32.5 cm for the TR-CPE200
product family.