HFSS plot fields help needed

Hello,

I am designing a dielectric sensor which consists of an interdigital capacitor (IDC) at the top layer. I found analytical expressions for an IDC in a 3-layer dielectric stackup and currently debugging my setup. (The theoretical estimate is 40% higher compared to HFSS). Although my expression evaluations is a suspect, if you have any suggestions in setting up HFSS properly for an IDC, your comments would be appreciated.

More importantly, I am trying to plot E-field distributions to help determine my optimum finger spacing.

Tradeoffs: (1) If finger spacing is too tight, all electric flux "resides" inside the top-layer dielectric (not helpful), but you get higher pF/unit-area. (2) If finger spacing is too large, I expect greater portion of the total electric flux to reside in the dielectric above the IDC (thus having larger dC/d(eps_dielectric) dependency).

I have tried using the Plot Fields -> E -> Vector_E. But it shows straight, colored arrows shooting perpendicular to an edge of my fingers. Not useful. Is there a clever way by which one can take div or curls and then plot the E-fields?

Thanks in advance,

After choosing your desired object or surfaces Try complex mag E instead of vector E. If you don't pick surfaces only you will get a cloud plot. HFSS will autoscale to the maximum E field found. Remember that quantities sjhown are peak and not RMS