Alternative Grids in (2+1)D

We have looked, so far, at waveguide mesh solutions to the (2+1)D parallel-plate equations on a rectilinear grid. We now mention some other possible grid arrangements, first hexagonal and triangular regular grids, then a radial grid. Because Appendix A is devoted to an in-depth exploration of the various types of mesh which have appeared in the literature, we will only take a brief look at these meshes here, with an emphasis on spatially-varying media.