• I.R.R. Shinton, R.M. Jones, N. Juntong
  UMAN, Manchester
• N. Baboi
  DESY, Hamburg
• N. Eddy, T.N. Khabiboulline
  Fermilab, Batavia
• T. Flisgen, H.-W. Glock, U. van Rienen
  Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock

We analyse the higher order modes in the 3.9GHz bunch shaping cavities recently installed in the XFEL/FLASH facility at DESY. We report on recent experimental results on the frequency spectrum, both beam and probe based. These are compared to those predicted by finite element computer codes, globalised scattering matrix calculations and a two-band circuit model. This study is focused on the dipole component of the multiband expansion of the wakefield.