Representation of moment matrix with predefined wavelet packet basis

A general wavelet packet tree is proposed to generate a predefined wavelet packet basis for the efficient representation of electrodynamic integral equations. The wavelet packet decomposition tree is constructed by zooming in along the spectral oscillation frequency of the free-space Green´s function. This is in contrast to the conventional wavelet transform which zooms in along the lowest spectral frequency. Numerical results show the transformed moment matrix based on the pre-defined wavelet packet basis has about O(N^1.3) above-threshold elements for typical scatterers