How can I calculate the E and H fields on the aperture of the antenna using the " Field probe" tab in CST Studio Suite  ? My aperture is like a Bow tie shape patch, but when I tried to select one after one coordinate on the aperture: the message appeared do you want to overwrite the previous  E field? Then how can I select my hexagonal aperture of the antenna to calculate E and H fields? I am attaching here the screenshot, kindly help me out. Thanks in advance!