Hi Vfurlan,
After simulating your model, it showed that the AR of your antenna around 1.6 GHz is larger than 3dB but not very high.
According to my experience the face that wave port should be defined on should bear the diemesion of 11*w and 10*h. W is the width of MS line and h is the substrate thickness. Your port face is a little small.
For the feeding part, maybe the extended ms line on the output port of hybrid should be truncated, which may affect the field distribution in antenna's substrate. Moreover, with further adjust of feeding position, a desirable AR should be observed.
Added after 28 minutes:
By the way, after reviseing your port's dimension, the axial ration at 1.5 GHz is 2 dB.
Is that desirable?