A signal coupling system interposed between a scanning probe and a measurement instrument provides signal communication between the scanning probe and the measurement instrument. The signal coupling system has a pre-stressed shape when the scanning probe is in a neutral position. The pre-stressed shape is designated to provide a characteristic impedance of the signal coupling system that varies linearly as a function of displacement of the scanning probe from the neutral position when the scanning probe is displaced, relative to the neutral position, over a designated range of displacements.