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 3. GQ EMF EF Meter RF Spectrum Power Analyzer
 What is dBm?

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T O P I C    R E V I E W
Mugless Posted - 06/20/2020 : 20:11:07
Hi Everyone,

Please explain the definition GQ 390 uses for dBm.

I assume the equation of dBm is:
dBm = 10 * Log10 (P_reading) / (P_reference)

If this is correct, please confirm that P_reference = 100,000 mW/m2, or 10 mW/cm2, since 0 dBm corresponds to that number:



Thanks,
Doug
3   L A T E S T    R E P L I E S    (Newest First)
EmfDev Posted - 06/23/2020 : 10:03:17
0dBm converts to 1mW but in power density becomes 10mW/cm2. 10mW/cm2 converts to 10^5 mW/m2.
Mugless Posted - 06/22/2020 : 16:00:28
Thanks,

So the conversion to 1 mW to power density involves a factor of 100,000 that takes into account other parameters including gain.
Is that the gain of the built-in antenna?
What are the other parameters?
Is the 100,000 factor derived from calibration of the GQ 390 against standard, reference equipment? If so, the fact that it is such a neat, round number is odd, if not even suspicious!!
EmfDev Posted - 06/22/2020 : 09:50:32
The RF power reference is 1mW. It is converted to density with other parameters including gain.

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