Conversion
 Tech.
 Track
Issued by: Teleconformity
Number: TCMY-027
Publication date: 2011-03-21
Last updated: 2016-02-17
Author: CEO

Conversion from dBm to uV/m@...metres

How to estimate the Field Strength at a certain distance, when not having test results from the ANEC or OATS available? Find below the approximation of conversion from Equivalent (Isotropic) Radiated Power to Field Strength per meter at a certain distance. The Correction Factor (CF, expressed in dB) for a frequency range and certain distance is approximately:

Emission type \ Distance Χ CF (1m) CF (3m) CF (10m) CF (30m)
ERP < 1 GHz 107.4 dB 97.4 dB 87.4 dB 77.4 dB
EIRP > 1 GHz 105.3 dB 95.3 dB 85.3 dB 75.3 dB

In the calculation fields below, we entered a default CF of 97.4 representing emissions < 1 GHz at 3m distance. Please change the CF in case you want to calulate with another frequency/distance.


mW to dBm conversion and vice versa → field strength at a certain disctance

Formula: mW = 10(dBm / 10); dBm = 10 log (mW); uV/m@Χ(m) =10((CF-|dBm|) / 20)

dBm = mW = W → CF= dB → uV/m @Χ(m)

mW = dBm → CF= dB →
uV/m @Χ(m)

Note: Only the orange fields require input.
Remark: Under 1 Ghz, the limit of 500uV/m@3m is reached at -43.42dBm; above 1 GHz at -41.42dBm.


uV to dBuV conversion and vice versa → termination with impedance resulting in dBm

Formula: uV = 10(dBuV / 20); dBuV = 20 log (uV); dBm = dBuV - 90 - 10 log (Z)

uV = dBuV → Z= Ω → dBm

dBuV = uV → Z= Ω → dBm

Note: Only the orange fields require input.
Remark: We took a default impedance of 50 ohms. You can change this value.


dBm to dBuV/m conversion and vice versa

Formula: dBuV/m = dBm + 77.21 + 20 log (fMHz)

dBm at f = MHz → dBuV/m

Note: Only the orange fields require input.


Note: The formulas on this page are not officially released. Use of the formulas is at the users responsibility. If any remark, or suggestion for improvement, please let us know by contacting us.




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