Impedance (Smith Chart) of 90 µm substrate height (Stafford Withington, Univ. Cambridge UK) and
the 50 µm thick substrate probe for use at the Caltech Submillimeter Observatory (CSO)
Comparison of Silicon and Quartz Radial probe impedance The original (Stafford Withington, Univ. Cambridge UK) design was on 90 µm substrate and has more reactance than the
thinner 50 µm CSO probe design. The fundamental probe impedance is too a large extend set by the substrate's phase velocity.
Effect of breaking WG wall (perfect Gnd)