RF exposure calculations for Sierra Wireless(MC5728)_v3

FCC ID: N7N-MC5728

RF Exposure Info

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FCCID_1955273

RF exposure calculations for Sierra Wireless MINI-PCI Express card CDMA when its antennas collocated with Cisco 802.11 a/b/g/n AP802 module antennas inside Cisco Router according FCC 47 CFR 1.307(b)(1). The following RF exposure calculation made for Mini-PCI Express card, model: MC5728V (Sierra Wireless Inc., FCC ID: N7N-MC5728) when his antenna collocated with antennas from 802.11 a/b/g/n module, model: AP802 (Cisco Systems Inc., FCC ID: LDKTG2050). Both devices are embedded into the Cisco 800 series model Router and have been evaluated and complied with FCC RF exposure requirements separately, however in case of Cisco 800 series model Router, these antennas are collocated less than 20 cm from each other and therefore cumulative RF exposure evaluation is required. This device will be only used with a separation of 20 cm or greater between the antennas and the user or nearby person. Device will be deployed in the fixed locations only but for purpose of this calculation will be consider as a mobile transmitter per 47 CFR 2.1091(b), and therefore has to comply with Maximum Permissible Exposure (MPE) limits. UMTS transmitter (FCC ID: N7N- MC5728) operates under Part 24E and 22H of FCC Rules in cellular and PCS bands and has the transmitting characteristics which are showing in Table1. Table1 Maximum Peak Antenna FCC Numeric Peak Frequency Range output Duty Gain for Part calculation MPE Antenna Gain for (MHz) power Cycle calculation MPE No. (dBi) (mW) 24E 1850- 1910 814.7 100% 1 1.2589 22H 824 - 849 959.4 100% 1 1.2589 a) 802.11 a/b/g/n transmitter (FCC ID: LDKTG2050) operates under Part 15C and 15E of FCC Rules in ISM and U-NII bands and has transmitting characteristics which are showing in Table2. Table2 Maximum Peak Antenna Numeric Peak FCC Frequency output Duty Gain for Antenna Gain Part Modulation Range power Cycle calculation MPE for calculation No. (MHz) (mW) (dBi) MPE 2412.0 - 15C 802.11n HT40 215.77 100% 4.01 2.5119 2462.0 5745.0 - 15C 802.11n HT40 328.1 100% 6.01 3.9811 5825.0 5180.0 - 15E 802.11n HT40 24.66 100% 6.01 3.9811 5240.0 2412.0 - 15C 802.11n HT40 215.77 100% 1.62 1.4454 2462.0 5745.0 - 15C 802.11n HT40 328.1 100% 5.02 3.1623 5825.0 5180.0 - 15E 802.11n HT40 24.66 100% 5.02 3.1623 5240.0 1. WiFi antenna type 1 PIFA antenna 2. WiFi antenna type 2 Dipole antenna

According 47 CFR 1.1310 FCC MPE limits for General population/Uncontrolled Exposure are showing in the Table3 Table3 Frequency Magnetic Field Strength [E] Power density Averaging Range (MHz) Strength (V/m) [S] (mW/cm²) time (min) Electric Field [H](A/m) 0.3 - 1.34 614 1.63 (100)* 30 1.34 - 30 824/f 2.19/f (180/f²)* 30 30 - 300 27.5 0.073 0.2 30 300 - 1500 ------- ------- f/1500 30 1500 -100,000 ------- ------- 1 30 f = frequency in MHz * = Plane-wave equivalent Power Density Based on FCC Bulletin OET 65, the MPE calculations in case of multiple transmitters have been e performed on the following and assumptions and equations: 1. For transmitters which operate in the frequency band with a same MPE limit the Power Densities are summed. The Total Power Density shall not exceed the Limit for this band 2. For transmitters which operate in frequency bands with a different MPE the Power Densities are calculated separately for each band, and then divided by Limit for each band. The sum of these ratios shall not exceed 1. 3. The calculation of the Power Density based on equation given in OET 65: E = √ (30 x P x DC x G) / d (Eq.1) and S = E2 / 3770 (Eq.2) Where: E = field strength in volts/meter P = power in watts DC = numeric duty cycle G = numeric antenna gain d = distance in meters S = power density in milliwatts / square centimeter Combining (Eq.1) and (Eq.2), S may be calculated as: S = (30 x P x DC x G) / (3770 x d2) (Eq.3) By changing units for P to mW and distance to cm, (Eq.3) can be written as: S = [30 x (0.001 x P) x DC x G] / [3770 x (0.01 x d)2] (Eq.4) Or: S = (0.0795756 x P x DC x G) / d2 (Eq.4)

Where: P = power in mW DC = numeric duty cycle G = numeric antenna gain d = distance in cm S = power density in mW/cm2 4. According Table3, limit for EV-DO transmitter in 824.7 – 848.31 MHz band shall be calculated at the lowest frequency (worst case) as: i. 824.7 / 1500 = 0.5498 mW/cm2 5. For the all frequency bands the highest level (worst case) of conducted power and antennas gain was used for calculation. The results of calculations are showing in Table 4. Table 4 Power Transmitting Ratio of the Transmitting Antenna Numeric density at 20 Device conductive Transmitter power frequency bands gain antenna cm from (transmitter) power duty cycle density to (MHz) (dBi) gain antennas (mW) its limit (mW/cm²) EVDO 824-849 814.7 100% 1 1.2589 0.1291 0.2348 EVDO 1850- 1910 959.4 100% 1 1.2589 0.3800 0.3800 802.11 2412.0-2462.0 215.77 100% 4.01 2.5119 0.1078 0.1078 a/b/g/n 802.11 5745.0 - 5825.0 328.1 100% 6.01 3.9811 0.2598 0.2598 a/b/g/n 802.11 5180.0 - 5240.0 24.66 100% 6.01 3.9811 0.0195 0.0195 a/b/g/n 802.11 2412.0-2462.0 215.77 100% 1.62 1.4454 0.0620 0.0620 a/b/g/n 802.11 5745.0 - 5825.0 328.1 100% 5.02 3.1623 0.2064 0.2064 a/b/g/n 802.11 5180.0 - 5240.0 24.66 100% 5.02 3.1623 0.0155 0.0155 a/b/g/n 1. WiFi antenna type 1, PIFA antenna 2. WiFi antenna type 2, Dipole antenna 6. Finally, the sum of ratios according (1.) and (2.) based on values in Table4. For WiFi antenna type1, PIFA antenna: EVDO (850) + WiFi (2.4G) = 0.2348 + 0.1078= 0.3426 < 1 EVDO (1900) + WiFi (2.4G) = 0.3800 + 0.1078 = 0.4878 < 1 EVDO (850) + WiFi (5G ISM band) = 0.2348 + 0.2598= 0.4946< 1 EVDO (1900) + WiFi(5G ISM band) = 0.3800 + 0.2598 = 0.6398 < 1 EVDO (850) + WiFi (5G U-NII band) = 0.2348 + 0.0195= 0.2543< 1 EVDO (1900) + WiFi(5G U-NII band) = 0.3800 + 0.0195 = 0.3995 < 1 For WiFi antenna type2, Dipole antenna: EVDO (850) + WiFi (2.4G) = 0.2348 + 0.0620= 0.2968 < 1 EVDO (1900) + WiFi (2.4G) = 0.3800 + 0.0620 = 0.4420 < 1

EVDO (850) + WiFi (5G ISM band) = 0.2348 + 0.2064= 0.4412< 1 EVDO (1900) + WiFi(5G ISM band) = 0.3800 + 0.2064 = 0.5864 < 1 EVDO (850) + WiFi (5G U-NII band) = 0.2348 + 0.0155= 0.2503< 1 EVDO (1900) + WiFi(5G U-NII band) = 0.3800 + 0.0155 = 0.3955 < 1 Conclusion: The Sierra Wireless Mini-PCI Express card: MC5728V (FCC ID: N7N-MC5728), when device transmitting antenna collocated with antennas connected to Cisco Wi-Fi module: AP802 (FCC ID: LDKTG2050) at the distance less than 20 cm and both devices are integrated into the Cisco 800 series model Router, is in compliance with FCC MPE limits for General Population/Uncontrolled Exposure as a mobile device (d>20cm).


Document Created: 2013-04-25 15:56:53
Document Modified: 2013-04-25 15:56:53
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