In general, a structure may support both electric ('''J''') and magnetic ('''M''') currents. The total electric ('''E''') and magnetic ('''H''') fields can be expressed in terms of the electric and magnetic currents in the following way:
:<math>E = E^{inc} + \iiint\limits_V \overline{\overline{G_{EJG}}_{EJ}(r|r') \cdot J(r') \, dv' + \iiint\limits_V \overline{\overline{G_{EMG}}_{EM}(r|r') \cdot M(r') \, dv'</math>
:<math>H = H^{inc} + \iiint\limits_V \overline{\overline{G_{HJG}}_{HJ}(r|r') \cdot J(r') \, dv' + \iiint\limits_V \overline{\overline{G_{HMG}}_{HM}(r|r') \cdot M(r') \, dv'</math>
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