Comparison of the effect of discretisation on absorbing boundary algorithms in the finite difference time domain method

With the recent growth of interest in the finite difference time domain method for the analysis of structures with open boundaries, much investigation is taking place into the use of absorbing boundary algorithms. Most analyses so far have not, however, taken account of finite discretisation. Here the properties of several popular absorbing boundary conditions are compared, and it is shown that, although formally identical when discretisation is not considered, differences in performance exist when realistic unit cells sizes are used. The best algorithm for general cases is identified.