Modelling of Propagation and Scattering in Waveguide Bends

A simple and accurate technique to determine the propagation and scattering properties of wave guide bends is presented. The modal cutoff frequencies and the corresponding field distributions are determined analytically. They are then used as basis functions in a moment method formulation of a reduced operator instead of the full Helmholtz operator at an arbitrary frequency. The scattering in a waveguide bend of finite length is then determined using the obtained modes in the Coupled-Integral-Equations Technique (CIET). Numerical results are compared with available data to demonstrate the validity of the approach.