Wideband measurement of extreme impedances with a multistate reflectometer

We present a technique for accurate wideband measurements of one-port devices with extreme impedances. Our technique uses a reflectometer with variable parameters (states) to obtain redundant measurements of the extreme impedance device. We process these measurements using statistical techniques that allow us to exploit the redundancy in order to increase the measurement bandwidth and reduce the measurement uncertainty. We demonstrate our technique for a simple setup containing a power splitter and an unknown variable reference impedance connected to one of its arms and an unknown extreme-impedance device connected to its other arm. The variable reference impedance is realized as either a set of mechanical standards or an electronically tunable impedance. Measurement results show that the repeatability of the reference impedance values is essential for achieving increased accuracy.