In previous publications, the effect of inhomogeneous beam loading Landau cavities due to a nonuniform fill pattern in storage ring has been studied with aim predicting resulting longitudinal profiles bunches and their time offsets relative main rf [T. Olsson et al., Phys. Rev. Accel. Beams 21, 120701 (2018)]. This work was extended treat dipolar coupled-bunch modes driven by beam-excited highe...