A Binary Phase-Modulation Technique of Measuring Microwave Phase Shift

A precision measurement system for the differential phase shift of a two-port device has been developed. The system is based on a two-channel circuit of which the phase of one channel is shifted 90° back and forth periodically. The response of the system is essentially independent on an amplitude change which is usually accompanied by the phase shift of the two-port device. An X-band measurement system has been constructed and examined. It is proved that the system has 0.02° resolution in phase angle. This system is also applied for the precise attenuation measurement by using a similar technique to the modulated subcarrier technique.