required help in hfss

i am trying to simulate a dng structure(both epsilon and mu are negative) using hfss.can any one help me in designing a rectangular horn antenna using hfss and obtain its radiation pattern.
i also require help regarding the design of the structure.i was facing difficulty in obtaining the phase of s11 and s21 for the structure.

thanks in advance.

use polyline concept in hfss for that.