Guys I am working on my CWNA paper and have hit a little point that I cannot get beyond (although you will probably think this is pretty simple).
It is the calculation for a circuit as below.
RF Circuit
AP--connector (A) -----Cable----Connector (B)----cable---- Connector (C)---Antenna (D)
AP is 100mW and the paper is explaining the calculation as below.
AP Point A Ponit B Point C Point D
100mW -3dB -3dB -3dB +12dBi =100mW /2 /2 /2 (x2x2x2) =100mW /2 /2 /2 x16 =50mW /2 /2 x16 =25mW /2 x16 =200mW
It was my understanding that all dB units (including dBi) are relative units and can be added and subtracted from other dB units - therefore the overall dB should be +3db = doubling the power - hey presto the right answer!
What I cant fathom is the calc shown above - why have they suggested a multiple of x2x2x2 ?
Can someone please explain why......only a little point but bloody annoying when your are learning this stuff for the first time!
Thanks