Frequency Domain Equation
To derive the time harmonic equation this physics interface solves, start with Ampère’s law including displacement currents (then called Maxwell–Ampère’s law), as these do not involve any extra computational cost in the frequency domain,
Now assume time-harmonic fields and use the definitions of the fields,
and combine them with the constitutive relationships
B
= μ
0
(
H
+
M
) and
D
= ε
0
E
to rewrite Ampère’s law as
