Mag_Jsurf: how does it works

I all,
I'm Francesco and I'm new here. I'm starting to use HFSS and I have a problem in plotting the Mag_Jsurf.

I still don't know how the function works:

What is the meaning of the list "Volume" where I can select the objects of the design? What's its scope exatly?
I would like to see the ampitude of the current on a monopole and I want to see if the current is a quart of sine function; how can I see it?
Somtimes I have the worning like this: "no current due to no avalaible solutions", why?
Any other explanation is welcome

Tnx a lot
Francesco

Francesco,
You will have to actually select a surface on the antenna to view the Surface current (Jsurf). On the other hand, by selecting an object, you can plot the JVol.