pcb directional coupler

Is it possible to get a sample from 50 ohm RF trace with another pcb trace near it ? how to design it to get 50 ohm impedance (10~20db coupling is good)

Yes its possible.
Use ADS linecalc for finding the trace width and separation after feeding the PCB details and the frequency of interest.

Hi,
here is a tutorial

http://qucs.sourceforge.net/docs/coupler.pdf

I use qucs its free and seems to work for RF (its free)

Is there any tutorial for design coupler with ADS LineCalc?