A cylindrical waveguide, provided with wedge-shaped metal vanes projecting radially inward from the wall of the guide, excited in the transverse electric (TE) mode, was analysed. The analysis was carried out considering the angular harmonics generated by the angular positioning of the vanes. A set of equations was generated in the Fourier amplitudes of field constants. The condition for nontrivial solutions for the field constants gave the dispersion relation of the structure. From the expression of power flow down the structure, its interaction impedance was also estimated. The shape of the dispersion characteristics and the value of the cutoff frequency as well as the interaction impedance characteristics of the waveguide were found to depend on the vane parameters their number as well as their radial and angular dimensions. The optimum vane parameters were obtained corresponding to the minimum variation of the slope of the ω-β dispersion plot, such parameters being useful from the standpoint of the bandwidth of a gyro-travelling-wave tube (gyro-TWT) using a vane-loaded cylindrical waveguide as the interaction structure. The dispersion and impedance characteristics, which were found typically for the TE01 mode as defined for the structure, taking four vanes, were more sensitive to the number and angular width of the vanes than to their radial depth. The value of the interaction impedance, calculated at the potential beam position, was found to be higher for a loaded waveguide than for an unloaded one, and it depended on the frequency of operation relative to the cutoff. The interaction impedance also depended on the position of the beam relative to the waveguide wall where it was estimated, and hence the optimum beam position corresponding to the maximum interaction impedance was found. The theory was validated against the dispersion characteristics reported elsewhere typically for four-vane magnetron-like structures excited in the 2π mode. Although the present study was restricted to ‘cold’ analysis of the structure in the absence of the electron beam, it could provide important feedback for analysing a gyro-TWT, using a vane-loaded cylindrical waveguide, and hence for predicting the structure parameters for the wide-band performance of the device.