Hittite 3port S parameters are compatable to eagleware. Download the file. In the schematic , on the top of the screen there will be elements that you can chose. Choose , linear. In the linear box you will see various components called out as 1, 2, 3 etc. These are port designations. Choose the 3 port. When you double click on the element you will see a "browse" button. Click the browse button, choose the 3 port file and close.
