Radiation and propagation of a surface-wave mode on a curved open waveguide of arbitrary cross section


  • David C. Chang,

  • Edward F. Kuester


A general scheme for calculating the change (both the real part and the imaginary part) of the propagation constant of a surface-wave mode on a general open waveguide structure is presented. By carefully keeping track of lower-order terms in the analysis, it is shown how approximations commonly made in other analyses can result in quite significant errors in the determination of the radiation loss. The resulting formulas require knowledge only of the fields and propagation constant of the corresponding straight waveguide mode, and the value of the radius of curvature of the waveguide axis. As a simple example, the curvature loss of a Goubau line is calculated.