what are the factors that can controal radiation patterns of slot antenna

hi i read in a paper that by changing feed of double slot antenna its radiation pattern in H plane will be tilted can any body tell me how can assymetric feeding tilt h plane pattern and no changing in e plane pattern?

Because of asymmetric structure, the pattern is bound to be asymmetric.
Maybe the structure what they explain has symmetry in 1 plane, thus no tilt in pattern on 1 plane. Do post the picture of the structure and if luck favours, you may get a better response from guys out here.

hi
i have attach the files having all images of a proposed dual slot antenna with assymetric feeding having tilted pattern in H plane only and not in E plane,can any body tell me the theory behind tilting and also why not tilted in Eplane