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
