Note on the reciprocity theorem for electrical systems

Summary It is shown by means of Maxwell's equations that the admittance matrix of a passive linear multipole placed in a constant magnetic fieldB₀ satisfies the extended reciprocity relationG_ik(B₀)=G_ki(–B₀) if the conductivity, permittivity and permeability tensors of the materials forming the multipole all satisfy the spatial symmetry relationT(B₀)=T(–B₀).