Mutual impedance spectrum expressed in Eq. (1) for the RPC- MIP configuration presented in Fig. 6. The amplitude (resp. the phase) is presented in the top (resp. bottom) panel. The Debye length is λ_De = 10 cm. The continuous line is computed using the algorithm implemented in Gilet et al. (2017), while the dotted lines correspond to the calculation described in this work, for two values of the ratio f_pe / f_ce of 10 and 50.