A New Absorbing Boundary Conditions Based on Orthogonalities of Waveguide Modes

An absorbing boundary condition(ABC) for both traveling and evanescent waves within waveguides is presented. By combination a convention ABC, it is proved that the ABC can be placed near a discontinuity without lossing the precision of the calculations, which results in reductions of CPU time and the computer memory. Numerical examples show that there is a good agreement between the data computed under the new ABC and the ones under the convention ABC.