Open boundaries Problem in a planar antenna on CST

Hi All,

I have the design of a planar antenna on CST(see fig) with the ground plane in the same plane as the antenna, the ground plane and the antenna are connected by a discrete port , when I make a frequency domain simulation I have this error "Resonant frequency domain does not support open boundaries"


Thank you in advance for any help. will appreciate if anyone could send me any infomation or tutorial on how to simulate a planar antenna.