I use e of 5000 for the insulator because in theory, high dielectric material helps to improve the capacitance of the electrodes (the metal plate), thus reducing the electrodes' impedance to the applied AC signals. This helps to reduce the voltage drop in the electrodes, so that larger applied voltage appears across the tissues (aka other layers between two insulators/plates). The ultimate goal is to achieve the E-field between 1-3V/cm in circle solid in the geometry.
In short, e>5000 is the recommended constant for my study regarding tumor treating fields.
Here are my control setup.
In case 1, I only have copper plates. As expected, the fields are going in all directions.
In case 2, three sides of the coppers are covered by an insulator, leaving one end exposed to the air - this is where the port is connected to. I'm little confused why most fields go vertically, rather than going horizontally through the insulator. Again, almost no fields in the insulator...
The purpose of case 3 is to study how the port's placement affects the fields. In case 3, all four sides of the copper plates are covered by an insulator. The port has to cut through the insulator. The fields drastically drops, compared to that in case 1 and 2. So I assume the port's placement has an impact on the simulation results, but I'm still confused why this happens.
Does the results of control setup look appropriate to you?

Sorry for a length post. Thank you.
Ha Nguyen