# How to rotate only one axis, being both on logarithmic scale

I have the following chart:

And I want to overlay an Excel graph over it. However, between the absice (Frequency, cps) and ordinate (Peak Displacement, in) there is an angle of 135 degrees. The problem is Excel graphs can only plot with orthogonal (90 degrees) axes.

How do I transform the values of the ordinate axis (Peak Displacement, in) so that the excel plot match the chart?

My wrong solution is: y = x + sqrt(2)*PD, (PD: Peak Displacement)

Identified problems are:

1. scales are logarithmic and all the straight lines of the following sketch are actually curves.
2. The origin is not (0,0) but rather close to (0.1, 0.0013)