[CST MW] Need help about bowtie antenna simulation in CST MW

Hello,
I have problem when tried to simulate the bowtie antenna.
My purpose is the S(1,1) and the impedance of antenna.
But the result seem incorrect.
Please help me to find out the incorrect point.
Thank you all!
Below is the dimension of bow-tie antenna:
L = lambda/2 = 38mm (f = 2.2GHz)
W = 11.5 mm
I've used discrete port to feed (Please refer the image attached).

discrete port should give good results. is the port placed at the center of the phase?