feeding method for circular polarized aperture coupled microstrip patch anteena

Hi all i want to design a circular polarized aperture coupled micro strip patch antena ? i am confuse how to use feed lines to to excite circular polarization mode through cross slots ?means how many feed lines we have to use one or two ?if somebody have any totorial for circular polarized ACMP antenna in HFSS kindly provide it.........

http://ocw.upm.es/teoria-de-la-senal...09_tuesday.pdf

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@ apeeet thanks for your reply but i am searching for feeding method in aperture coupled patch anteena if u have any document or tutorial related to it kindly post it