  We study the electrodynamic impedance of percolating conductors with a
pre-defined network topology using a scanning microwave impedance microscope
(sMIM) at GHz frequencies. For a given percolation number we observe strong
spatial variations across a sample which correlate with the connected regions
(clusters) in the network when the resistivity is low such as in Aluminum. For
the more resistive material NbTiN the impedance becomes dominated by the local
structure of the percolating network (connectivity). The results can
qualitatively be understood and reproduced with a network current spreading
model based on the pseudo-inverse Laplacian of the underlying network graph.
