MPE 2400

FCC ID: OWS-NIC45

RF Exposure Info

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FCCID_1953444

Silver Spring Networks Report No: 13PRO004B FCC ID: OWS-NIC45 IC: 5975A-NIC45 Model No.: NIC45 MAXIMUM PERMISSIBLE EXPOSURE LIMITS §1.1310 The criteria listed in Table 1 shall be used to evaluate the environmental impact of human exposure to radio-frequency (RF) radiation as specified in §1.1307(b), except in the case of portable devices which shall be evaluated according to the provisions of §2.1093 of this chapter. Page 26 of 37

Silver Spring Networks Report No: 13PRO004B FCC ID: OWS-NIC45 IC: 5975A-NIC45 Model No.: NIC45 CALCULATIONS Given E = √ (30 * P * G) / d and S = E ^ 2 / 3770 where E = Field Strength in Volts/meter P = Power in Watts G = Numeric antenna gain d = Distance in meters S = Power Density in milliwatts/square centimeter Combining equations and rearranging the terms to express the distance as a function of the remaining variables yields: d = √ ((30 * P * G) / (3770 * S)) Changing to units of Power to mW and Distance to cm, using: P (mW) = P (W) / 1000 and d (cm) =100 * d (m) yields d = 100 * √ ((30 * (P / 1000) * G) / (3770 * S)) d = 0.282 * √ (P * G / S) where d = distance in cm P = Power in mW G = Numeric antenna gain S = Power Density in mW/cm^2 Substituting the logarithmic form of power and gain using: P (mW) = 10 ^ (P (dBm) / 10) and G (numeric) = 10 ^ (G (dBi) / 10) yields d = 0.282 * 10 ^ ((P + G) / 20) / √ S Equation (1) where d = MPE distance in cm P = Power in dBm G = Antenna Gain in dBi S = Power Density Limit in mW/cm^2 Equation (1) and the measured peak power is used to calculate the MPE distance. Page 27 of 37

Silver Spring Networks Report No: 13PRO004B FCC ID: OWS-NIC45 IC: 5975A-NIC45 Model No.: NIC45 LIMITS From §1.1310 Table 1 (B), S = 1.0 mW/cm^2 RESULTS No non-compliance noted: Worst-case RF exposure condition is for internal antenna operation as the gain is higher Power Density Output Antenna S, mW/cm2 Limit Power Gain at 20cm (mW/cm^2) (dBm) (dBi) 1.0 22.73 3.50 0.08 MPE Distance: 5.8 cm (for 2400 MHz operation alone). NOTE1: This radio is a dual 900/2400 MHz FHSS module and both transmitters can be active at the same time. When both transmitters are operating: MPE Distance, cm = 16.5cm. This distance is derived in a separate attachment. NOTE2: For mobile or fixed location transmitters, minimum separation distance is for FCC compliance is 20 cm, even if calculations indicate MPE distance is less. Page 28 of 37


Document Created: 2013-04-20 11:14:42
Document Modified: 2013-04-20 11:14:42
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