A remotely-controlled coaxial switch for impedance standard calibration

A switch which permits the connection, in sequence, of two four-terminal-pair impedance standards to an automatic RLC bridge is presented. The purpose of the switch is to automate the process of impedance calibration by 1:1 substitution. The switch is capable of engaging four coaxial lines at a time (switching both the internal conductor and the screen of each line); the electrical contacts are British Post Office (BPO) MUSA connectors; the switch, in the closed position, adds around 2 mΩ for each coaxial line to the electrical path. The switch is moved by pneumatic actuators to avoid any electrical interference, and can be remotely controlled via RS-232 interface. Measurement examples are shown