Tests for time domain EM solvers for stability and towards passivity

Stability issues for time domain integral equation based EM solvers have been a problem for a many years. In this paper, we consider ways to test for stability as well as other criteria towards passivity. The tests are designed to monitor the EM solver while the time domain solution is progressing. Hence, the solution can be terminated and improved with a passivization technique when a violation of the criterion has been detected. Also, the tests help to understand the cause of instabilities and results can be used for passivization.