basically in branchline coupler for Z0=50 ohm, my dimesnsions are
conductor width=598um
gap width=296.77um
length=1.744mm
This, W+2G=1.17mm
for 18GHz, lambda=16.66mm
If i use the given formula then W+2G<0.24mm else higher order modes will exist in the CPW and affect circuit performance
But i am not seeing any negative effects/warnings in my circuit s-parameter simulation. In fact, i get better values as i increase W.....so on what grounds should i limit W??
The CPW i am using is without backside metallization..