Rio, A static electric field is one that is not changing with time, i.e. generated by DC voltage. Fastcap calculates capacitance by evaluating electric fields emitted and terminating on conductors as if those fields were generated by DC voltages. If this capacitor is used with a voltage source that is varying slowly compared to the physical size of the conductors then we say it is quasi-static, meaning that the static field capacitance is a good approximation. If the voltage source is varying rapidly compared to the physical dimensions than you cannot use FastCap. For example if I have a parallel plate capacitor with plate dimension 10 meters then I can use FastCap if the signal that I will place on this capacitor is 1KHz, but I cannot use FastCap if the signal will be 1GHz. Same idea applies to FastHenry.
Magneto-quasistatic & Electric-quasistatic
Posted - Dec 02 2011 : 15:42:35
