how to create 90 degree phase different

Hi all,

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.

Thanks before...

rc cr circuits mentioned in RF microelectronic by RAzavy

use parallel line coupler it will give you 90 phase difference, you can use hybrid also.

hybrid can be used.
Phase can also be varied by altering the cable length r strip length.

Use single λ/4 microstrip line, it will give 90° phase shift.

if you want to create cicular pol. with a patch antenna see http://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.

http://www.microwaves101.com/encyclo...fters_HPLP.cfm

poly phase filter can you use these passive devices

you can use LC to do that