Characteristic strain as a function of frequency. We consider the GW signal from an SMBH binary located at a = 50 au (solid lines) as well as a_c(Ω_⋆ = i_⋆ = 45°), which corresponds to the red dashed line from the left panel in Figure 3. We consider a range of masses varying from 10 M_⊙ (dark blue) to 10⁶ M_⊙ (light blue). In all cases we adopt e_c = 0.9. We adopt a LISA observational time of 4 yr. The LISA noise sensitivity is shown in black (Robson et al. 2018).