Cylindrical waveguide mode convertor for azimuthally symmetric transverse electric modes

The propagation of the guided modes in a cylindrical waveguide with imperfectly conducting walls and with the radius having a weak harmonic variation in the axial direction is investigated using the expansion of the fields in terms of the ideal normal modes. The theory is applied to the design of a mode convertor that selectively transforms the power in the TE_0r mode to the TE_0s mode. The spectral response of the mode convertor is analysed and the possible improvements of the basic design of the mode convertor are discussed.