Chukwudi,
This is why I directed you to the “Basic Examples & Analysis” webinar as in that video I specifically show how to obtain the reflection spectrum from the power spectrum utility. I am not sure what version of the product you are using because there is no “spectrum analysis” tool in the existing product.
In the power spectrum tool, if you make sure the normalized box is checked then the results are normalized to the power and as such they vertical axis is a fraction of the input power.
Scott