I'm not sure I know what you mean by "probe" the antenna...? If you want to excite/add an s-parameter port to the structure, you can use a 'discrete port' at a given set of (x,y,z) coordinates. Alternatively, if you want to visualise the fields/surface currents within the structure, add the appropriate "field monitor" found under the Solve/ menu bar item.
Hi thylacine,
Thanks for your quick reply! Actually I wanted to observe the higher order modes of a 2arm spiral antenna, i.e. Mode 3 & Mode 5, by trying to probe the spiral at different position (like the one in the prev fig) to observe the relative power density at those modes. It is expected that the power density will start to decrease as the mode increases (as mode1 is the active region, fig2). Please, do you have any idea how to do this?
Hmm - still not sure I exactly follow. If you connect a discrete port at the centre of the spiral (connected to each of the two spiral arms), configure a 0 - 15 GHz frequency sweep, request the calculation of a "current density" plot at the frequencies of interest and hit 'go' on the transient solver - you'll end up with the plot of Fig 1 (at each of your frequencies)
It'll take a better CST user than me to tell you how to generate Fig 2. though
Fig2 is actually a result from a recent paper on spiral antenna. I also had no idea how he did it =)
Btw, do you know what is the function of the probe in CST (Solve-Probes)?