Sometimes the EQS solver refuses to converge and a warning like this appears in the log:

Dynamic range is 1.1096e+12 (lower limit solid Background (1) and upper limit solid Cover Loops 3 (1.1096e+12)).
WARNING: The material parameters differ considerably, please consider to decrease the dynamic range of the material parameters or increase the solver's relative tolerance.

Technical explanation:

The problem that you are trying to solve is very difficult for the EQS solver: some regions are dominated by ohmic current effect (the materials with high conductivity), some regions are dominated by displacement currents (the free space or materials with very low conductivity) and the solver is trying to accommodate both at the same time.


Option 1: Change the material properties of all the metals to PEC. This will reduce the "dynamic range" a lot and the solver should converge.

Option 2: Use either the Quasi-static or the Ohmic-QuasiStatic solver, intead of QuasiStatic. Whether or not this is a good idea depends on the application.

Option 3: Reducing the solver tolerance (e.g. from 1e-8 to 1e-12) may eliminate the error, but at a high computational cost.