MPE Claculation

FCC ID: RI7GE864Q2

RF Exposure Info

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FCCID_1205878

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MPE Calculation for GE864-QUAD V2 - OET Bulletin 65

The FCC requires that the calculated MPE be equal to or less than a given limit dependent
on frequency at a distance of 20 cm from a device to the body of a user.
The transmitter operation for the GE865-QUAD V2 covers GSM850 and PCS1900 operating
bands.
The following FCC Rule Parts are applicable:
Part 2.1091(c)
Part 22 GSM850 devices operating at frequencies at or below 1.5GHz with effective radiated
power (ERP) of 1.5 watts or more are subject to routine RF exposure evaluation, otherwise
they are categorically excluded.
Part 24 PCS1900 devices operating at frequencies above 1.5GHz with effective radiated
power (ERP) of 3 watts or more are subject to routine RF exposure evaluation, otherwise
they are categorically excluded.

Part 24.232 (b)
Mobile/ Portable stations are limited to 2 Watts EIRP peak power

Part 22.913 (a)(2)
The ERP of mobile transmitters and auxiliary test transmitters must not exceed 7 Watts.

The MPE calculation as given in FCC OET Bulletin 65, page 19 is used to calculate the safe
operating distance for the user.

S = EIRP/4 π R2
Where S = Power density
EIRP = Effective Isotropic Radiated Power (EIRP = P x G)
P = Conducted Transmitter Power
G = Antenna Gain (relative to an isotropic radiator)
R = distance to the centre of radiation of the antenna

For GSM 850
Transmitter frequency range = 824MHz to 849MHz
Max. Conducted Transmitter Power = 33dBm (2.0W) @ antenna socket
From Part 2.1091(c) routine RF exposure evaluation is required for ERP> 1.5W.
Antenna use with gains above 0.86dBi would therefore require RF exposure evaluation.

ie: EIRP = 33 +0.86 = 33.86dBm for 0.86dBi antenna
ERP = EIRP – 2.1dB (half wave dipole gain)
ERP = 33.86 – 2.1 = 31.67dBm (1.5W limit)

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MPE Requirement
From table 1 (b) - Limits for General Population/ Uncontrolled Exposure of
FCC Rule Part 1.1310 for GSM850

S = f/1500 mW/cm2 (f = operating frequency)

S = 824/1500 = 0.55 mW/cm2 (worst case)

MPE Calculation to Determine Safe Maximum Antenna Gain (G)

Values: S = 0.55 mW/cm2
P = 2000mW
R = 20cm

S = PxG/4 π R2
0.55 = 2000xG/(12.56 x 202)
0.55 x (12.56 x 202) = 2000 x G
0.55 x (12.56 x 202)/ 2000 = G

G = 1.38 (1.40dBi)

Calculation for Maximum radiated power output
For 1.4dBi gain antenna
Power = 1.38 x 2.0 = 2.76W EIRP (34.4dBm)
ERP = EIRP – 2.1dB (half wave dipole gain)
Max. ERP = 34.4 – 2.1dBm = 32.3dBm
This is below the Part 22.913 (a)(2) limit of 7W ERP
The 1.4dBi maximum gain antenna will therefore comply with the required FCC rule parts.

For PCS1900
Transmitter frequency range = 1850MHz to 1910MHz
Max. Conducted Transmitter Power P = 30dBm (1.0W) @ antenna socket

Calculation for Maximum radiated power output
Maximum antenna gain G that can be used to comply with the maximum transmitter power
limit of 2W EIRP of Part 24.232(b) is calculated as:
PxG =2
ie: G = 2/1 = 2 (3dBi)

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For 3dBi antenna gain maximum ERP is < 3.0W, so from Part 2.1091(c), routine RF
exposure evaluation is categorically excluded. The 3dBi maximum gain antenna will
therefore comply with the required FCC rule parts.

Conclusion
The required 20cm RF exposure limits for General Population/ Uncontrolled Exposure FCC
Rule Part 1.1310, and ERP Part 22.913 (a)(2), EIRP Part 24.232 (b) maximum transmitter
power limits will not be exceeded for the GE865-QUAD using antennas having a maximum
gain of 1.4dBi (850MHz) and 3.0dBi (1900MHz) respectively.

Document Created: 2009-07-21 12:07:52
Document Modified: 2009-07-21 12:07:52

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