MPE

FCC ID: N7NAC850

RF Exposure Info

Download: PDF

FCCID_595520

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
where
d = MPE distance in cm
P = Power in dBm
G = Antenna Gain in dBi
S = Power Density Limit in mW/cm^2

Rearranging terms to calculate the power density at a specific distance yields

S = 0.0795 * 10 ^ ((P + G) / 10) / (d^2)

LIMITS

From §1.1310 Table 1 (B), the maximum value of S = 1.0 mW/cm^2

RESULTS

No non-compliance noted:

Mode MPE Output Duty Antenna Power
Distance Power Cycle Gain Density
(cm) (dBm) (%) (dBi) (mW/cm^2)
800MHz Celllar 20.0 32.00 0.25 8.00 0.50

Mode MPE Output Antenna Power
Distance Power Gain Density
(cm) (dBm) (dBi) (mW/cm^2)
1900 MHz PCS 20.0 29.00 4.00 0.24

NOTE: For mobile or fixed location transmitters, the minimum separation distance is 20
cm, even if calculations indicate that the MPE distance would be less.

Document Created: 2005-10-25 14:01:13
Document Modified: 2005-10-25 14:01:13

© 2024 FCC.report
This site is not affiliated with or endorsed by the FCC