Here are some wavelet formulations to expand our imagination, I hope this is not crackpot math or physics:

[Making electromagnetic wavelets](http://arxiv.org/pdf/math-ph/0402006v3.pdf)

[Eigenwavelets of the Wave Equation](http://arxiv.org/pdf/math-ph/0408044v3.pdf)

[Wavelet Method for Numerical Solution of Wave Equation with Neumann Boundary Conditions](http://www.iaeng.org/publication/IMECS2011/IMECS2011_pp1513-1516.pdf)