CPW Mode Configuration

To model co-planar waveguide mode in Sonnet, three ports using the same port number, one positive and two negative, should be used. The CPW line requires a combination of -1, +1 , -1 ports. Em sums the total current going into all the positive ports with the same port number and sets that equal to the total current going out of all the ports with that same negative port number. For the CPW mode, em sets current flowing into port +1 to be equal to the current flowing out of both port -1. An example is shown below.  Zp is the impedance of the port.