Abstract：A variational expression of the propagation coefficient of the dominant mode in twisted rectangular waveguide is derived on the basis of the theory of the nonstandard eigenvalue problems, and the numerical results are compared with that of perturbation approach. It illustrates that there is no infinite series in the variational expression, and the variational results are more accurate than the perturbational ones, especially when the twisted angular period becomes bigger.
1996, Vol. 18 
