Basic HFSS help needed - how do I add a wave port to coax?

I want to try to simulate an antenna consisting of a piece of coax with a slot in the braid. i.e. Leaky Feeder. I'd like to look at the power at each end of the feeder, so want to put 2 ports. The attached file has the important bits, but the dimensions are purposely changed to make the thing easier to see.

But whenever I try to add ports to coax I seem to get in a mess.Sometimes when I do HFSS -> Excitations -> Wave Port. I get a window which shows two conductors, but on other times it only shows one. But I'm never sure when to tick the "reference" or not. What does that mean?

The documentation for HFSS seems to be beyond the code, as what I see does not exactly follow what I see in the tutorials which have coax.

Can anyone describe the exact process in HFSS 13 of adding a port to coax?

In the attached file, I've drawn a circle for Port1 and Port2, as I've seen in some examples. This has a diameter equal to that of the dielectric of the coax. Or should the circle have a radius equal to the outside diameter of the braid, rather than the inside?

What (if any) of inner and braid should be a reference?

If u have 2 conductors at the point u want to add port ... One conductor is selected as a reference for the wave port .. it is just like + and - terminals of a battery.
In the other case of single conductors (Waveguide) there is no reference.

Does it matter which is selected as a reference?

What I find odd is that sometimes I seem to have a choice of two conductors, other times only one, despite this is coaxial cable, and not hollow waveguide. If I only see one conductor and it's a coaxial cable, do I have a mistake? Should there always be two conductors for a coax in HFSS?

Check it to see if it is driven modal or driven terminal (it should give 2 conductors)..

Thank you. Should both give 2 conductors?

I think I was going wrong by putting PEC over the complete coax (including the braid). It seems to be best to cover the inner conductor and the dielectric, but not the outer conductor. At least that's what I think I found! I find the ports in HFSS rather confusing.

The outer conductor should not be placed PEC. HFSS by default consider it as PEC...

U can view it in boundary solver display view.. (Outer)..

For driven terminal u will get 2 conductors whereas for driven modal only one conductor.