Common-arm counter propagating phase bridge for vibration sensitivity measurement

Current methods for measuring the vibration sensitivity of microwave devices are limited primarily by choice of cables connecting a stationary platform to a vibrating actuator. We experimentally compare the current (“conventional”) method with a new (“modified”) common-arm counter propagating (CACP) technique for evaluation of two-port devices. We demonstrate that a CACP method reduces the vibrational noise floor of an optimized measurement system at 10 GHz by up to 25 dB. Common-mode disturbances from the vibration of cables and circulators contained in the measurement loop are rejected to first order. The CACP method enables accurate measurement of devices with low vibration sensitivity. The sensitivity measurement of such devices is normally limited by a conventional measurement system´s noise floor. Our system is based on similar work at optical frequencies by Nelson et al. [2].