design of the aperture-coupled microstrip

rectangular patch of dimensions ( a*b) a=049*lamda0/(epsilon r)¨1/2 , b ?
the microstip patch is fed by a microstrip line((Lf+L0)*Wf) through an aperture in the common groud plane of patch and microstrip feed, the aperture is demensions (L*W).


I seek if somebody can help me to give me the method to find these values b ,Lf,L0 Wf,L and W .

thank you