J. L. Herring, M. Righi and W. J. R. Hoefer
IEEE MTT-S International Microwave Symposium, Denver, CO USA, June 8-13 1997, pp 325-328.
Modal absorbing boundary conditions are applied to a graded mesh using the hybrid node, and to homogeneous waveguides of arbitrary cross-section. The best performance is obtained with rectangular waveguides but examples show that the method can also be used for other geometries. A T-junction circular - to - sidecoupled rectangular waveguide example is given.