Help! units of port signals in CST is unclear

Hi all!
I'm trying to to get an estimation for a path-loss through space/material - I have tx antenna,
but I don't understand what the units mean - suppose the o1,1 signal is the one radiated from the antenna,
and a probe distant from it is recording field reaching 200 V/m . obviously I want to compare it with o1,1 .
but what is the relation between the o1,1 signal and the V/m units of the recorded probe?
how can I compare the path loss in this case ?
what does the units of the port signals mean ?

any help will be blessed!