f i understand ur question correctly its true. The currents in patch antenna are different in patch directions and the radiation is actually because of this. In one side the currents are in same direction and other size varies oppoiste to patch size. consequently leading to resonate at the particular frequency.
Kraus and Milligen are good for you to have a look
thanks for your answer, but unfortunateley I didn't get it.
Let's define directions.the resonant length L= lambda/2 is in x-direction, the width W in y-direction. so currents are flowing in x-direction as expected: maximum current in the center x=L/2 and minimum current at the edge x=0 and x=L. What I was talking about is the fact that the current in x-direction at y=0 and y=W is much larger than the one at y=W/2. but all of them are flowing in the same direction. which currents have you been talking about?