CST Ports decoupled regions

[kato01]

I am running a coaxial horn in CST. I defined the port that cover the inside cylindrical waveguide and the outside coaxial waveguide
I receive this warning:

"Port 1 contains 2 decoupled regions. Please consider defining one port for each of these regions. Note that electric shielding is enabled. Disabling electric shielding could eliminate the problem"

How to fix this problem?

I looked in the Help but I did not understand what to do.
I understand I need to increase the mesh density but:
1. What to mesh finer: the Port surface or the whole body?
2. I increased the mesh quite a bit and still got the same warning
3. In the help it says deactivate "electric shielding. Well this option IS unchecked

They have a macro in the Solve/Port menu "Allow overlapping Ports". I run it and still get the same warning

 

[yefj]

if i remmeber correctly once i got that error when i had a non uniform input feed.
maybe you should make the coax simpler?

 

[PlanarMetamaterials]

I think you should just do what it suggests -- decompose your port into two separate ports; one covering just the inner waveguide, and one outside that covering just the region between the waveguide and the outer coaxial conductor. This would consist of two concentric objects: the inner one a circle and the outer a disc with a hole that is filled by the inner circle.

 

[kato01]

I did, however CST port definition is a square even thought the selection is a circle or annular circle. So they overlap again