hi

Two "out of phase" signals on 2 high frequency transmission line are need to be combined at the end. If the delay of both lines will be equal, they will arrive at same time. if not, o/p will have significant harmonics. can you guide me what are the ways to eliminate these harmonics?

Thanks

 

I am not clear why if the delay is different this would generate harmonics? The sum of the two sine waves will still be a sine wave even if they are out of phase: http://2000clicks.com/mathhelp/GeometryTrigEquivPhaseShift.aspx

To match the phases, use the same cable for both and match the lengths.
To remove harmonics, use a low pass filter.