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SanDisk Corporation
Page 13 of 17
DoC Report
2006137
02/02/07
5.2 FIELD
STRENGTH
CALCULATION
The field strength is calculated by adding the Antenna Factor and Cable Factor, and subtracting the
Amplifier Gain (if any) from the measured reading. The basic equation with a sample calculation is as
follows:
FI(dBuV/m) = SAR(dBuV) + SCF(dB/m)
FI = Field Intensity
SAR = Spectrum Analyzer Reading
SCF = Site Correction Factor
The Site Correction Factor (SCF) used in the above equation is determined empirically, and is
expressed in the following equation:
SCF(dB/m) = - PG(dB) + AF(dB/m) + CL(dB)
SCF = Site Correction Factor
PG = Pre-amplifier Gain
AF = Antenna Factor
CL = Cable Loss
The field intensity in microvolts per meter can then be determined according to the following equation:
FI(uV/m) = 10
FI(dBuV/m)/20
For example, assume a signal at a frequency of 125 MHz has a received level measured as 49.3
dBuV. The total Site Correction Factor (antenna factor plus cable loss minus preamplifier gain) for
125 MHz is -11.5 dB/m. The actual radiated field strength is calculated as follows:
49.3 dBuV - 11.5 dB/m = 37.8 dBuV/m
10
37.8/20
= 10
1.89
= 77.6 uV/m
