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Reg. Transmit & Receive Power - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

Amateur Radio | Antennas | Circuits & Components | Systems | Test & Measurement

 Post subject: Reg. Transmit & Receive power
Posted: Fri Dec 22, 2006 7:27 am 

Joined: Fri Dec 22, 2006 6:44 am
Posts: 1
Location: INDIA
Can any one tell me the reson for changing the BTS transmit power in +ve value( dBm or Wtts) while the Mobile receiving power is -ve value.

look forward for your reply

 Post subject:
Posted: Thu Jan 11, 2007 1:19 pm 
User avatar

Joined: Thu Jan 11, 2007 12:59 pm
Posts: 16
Not sure if I understand you right, but I assume that you mean that output power is mentioned for an example as +20dBm, ie 100mW. A reciever will only recieve a fraction of this and according to the logarithmics it'll be for an example -60dBm, ie one millionth of a mW.

Some more information at


 Post subject:
Posted: Fri Jan 12, 2007 4:35 am 
User avatar

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK
If the power at the input to a Black Box 2 port device is +N dBm and the attenuation through the Black Box is greater than N dB, then the output expressed as dBm will be a negative value, because you have used up all the +N decibels and the "Bank Account" goes into negative territory.

Your question, as Jens implies, was rather cryptic. Some more details would help us explain better.

Posted  11/12/2012

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