Author 
Topic 

Mugless
Australia
11 Posts 
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 

Reply #1
EmfDev
1483 Posts 
Posted  06/22/2020 : 09:50:32

The RF power reference is 1mW. It is converted to density with other parameters including gain. 


Reply #2
Mugless
Australia
11 Posts 
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 builtin 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!! 


Reply #3
EmfDev
1483 Posts 
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. 



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