RF Exposure MPE

FCC ID: OWS-NIC506

RF Exposure Info

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FCCID_936028

MPE Calculation
for
FCC ID: OWS-NIC506
IC: 5975A-NIC506

The SilverSpring Networks eBridge is 900MHz FHSS module.

Operating Environment:
The operating environment for the for the radio in all cases is a fixed, uncontrolled environment, however, the
devices are classified as being “Mobile”, Therefore the exposure at 20 cm is calculated. However the level of
exposure at 20 cm is above the limei, therefore the device will be installed at a distance of 23 cm. See the
calculations below.

Fixed, Uncontrolled Environment: (OET65/C Appdx A)
The FCC limit for the power density for uncontrolled exposure to RF devices operation at 900MHz at a distance of
20 cm is:
f (MHz)/1500 = 900/1500 = .6mW/cm2
Power density is calculated from the following equation

Exposure (mW/cm2) = EIRP(mW) * Duty Cycle
4*PI* Radius2(cm)

Where:
Radius = 20 cm
Duty Cycle = assumed to be 100% to yield a worst case result.
The maximum allowed external antenna gain on 900MHz is 6 dBi
The transmit power is 29.94 dBm, 986.28 mW

900MHz ISM band MPE distance Calculation at 20cm
Using the EIRP measured on 900MHz ISM band.
MAX Pout: 29.94dBm MAX Ant Gain 6 dBi (4 x)
EIRP: 35.94 dBm (3945.12mW EIRP)

Calculating power density at a distance of 20 cm yields:
Power = 3945.12 * 1 3945.12 .7848 mw/cm2
Density 4 * Pi * 202 5026.54

900MHz ISM band MPE distance Calculation at 23cm

This is above the allowable power density level for a 20 cm separation distance. Therefore the device will be
installed in such a manner as to provide a separation distance of 23 cm between the device and all persons.

Power = 3945.12 * 1 3945.12 .5934 mw/cm2
Density 4 * Pi * 232 6647.61

Document Created: 2008-02-03 13:09:51
Document Modified: 2008-02-03 13:09:51

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