Broadband six-port reflectometer junction

The letter describes a six-port junction for use in a reflectometer having a theoretical bandwidth equal to that of its four constituent directional couplers. Their voltage coupling coefficients can be chosen to optimise the resolution in measuring voltage reflection coefficient ¿, given the same fullscale indication for each of the four detectors. Experiment indicates that, using thermistor detectors, a standard deviation of less than 5×10¿4 in |¿| can be achieved with less than 1 mW power incident on this junction.