A Novel N-port Characteristic Formulation in Lossy Cases

In this paper, we propose a novel N-port characteristic mode (CM) formulation. By leveraging the current-far-field-basis, the radiated-power-related (RPR) matrix is constructed, which is then utilized to develop the left-hand side (LHS) matrix of the proposed CM formulation. The resulting eigenvalues give the resonance and dissipation properties of the whole system. Specifically, the real part is the ratio of the reactive power to the active power, while the imaginary part represents the modal radiation efficiency, thereby fully identifying the modal behavior of the N-port system.