I'm still learning in designing patch antenna...
I want to ask how to make a 90 degree phase different current?
for example bending the the microstrip line.
is there any other method to do that?
and will it also change the magnitude?
actually I want to keep the magnitude remain unchanged.
if you want to create cicular pol. with a patch antenna see https://en.wikipedia.org/wiki/Patch_antenna
there you will see a circular patch with two slots on it. this will change the current distribution on the patch and gives you circular pol.