[CST]slits loaded patch antenna

i tried to repeat the work of a slit loaded patch antenna ,but my simulated results are quite different from what the paper shows.
Could anyone pls help me check where the problem is?
Thank you!

Hi I will try to run ur structure and let you know.
Habeeb.

Your case is very similar with my first exercise about broadband-patch antenna.
I have found that your port is not defined properly!
I called to CST supporter and he said the waveguide port should not cover the outer conductor of coaxial cable.
That means, you should only check the face of the middle dielectric of cable and define port from that face.
Note that , if the port is larger or touch the outer conductor of cable, there are some higher proapgating mode, and they might effect your accuracy results.
Therefore, we can increase the diameter of the outer conductor without any change in the results in order to that the waveguide port does not touch or cover the outer conductor.
You can see that the port signal is decayed very fast and the energy can not converged to the desired dB!
In other word, your structure is unstable time by time!
Please try define port in a proper way and run case again. Let me know how it changes!
Best regards!

hi KhangKhang,
i really appreciate your special concern on my post!
it's been a habit for me to draw a metallic coat for construct the coax cable and always cover it in the waveguide port. i noticed it's not necessary to draw the outer conducter at all, according to the circular patch example in the CST official tutorial.
however, i'm still not quite clear why the structure is "unstable" if my port is used.
BTW, i once modeled a structure, using the port with and without a coax metallic coat, yet found little difference in the port calculation result.
Anyway, i shall accept your advice and try again.
Thank you!