Can the magnitude of the reflection coefficient (ρ) be greater than 1?
Yes, under conditions of quite reactive Zo (which will usually be a negative reactance) and a highly inductive load, ρ may be greater than 1. This is unlikely to happen with practical lines at HF and above. Note that an instrument calibrated for Zo real should never show ρ > 1, it is a sign of mismatched detectors in such an instrument. Reverse the instrument and see if it still happens.
