High-Performance 18-GHz Microwave Readout Flexured Mass Accelerometer

A 10 8 dynamic range Flexured Mass Accelerometer utilizing microwave cavities and readout electronics operating at 18 GHz has been shown to be capable of achieving 1-µg bias stability with +0.01°C temperature control. Developments previously reported for the device operating at 10 GHz .1 were implemented. The flexure cartridge, designed to eliminate anelastic and hysteretic effects during device static or tumble testing, was incorporated into the 18-GHz device. Two device configurations were fabricated and tested for resolution, drift stability, and tumble bias repeatability in a 1-g field. One was constructed entirely from Superinvar, save for the ceramic flexure cartridge, while the other, which also used a similar ceramic flexure cartridge, was of a hybrid construction employing Superinvar microwave cavities and a ceramic Zerodur housing. Two breadboard configurations of low-noise 18-GHz electronics were designed, built, and tested successfully to support these evaluations. The best results achieved included the following: resolution, 0.35 µg; drift stability with a rigid insert substituted for the flexured proof mass, <8 µg rms over 2 h; drift stability with the flexured proof mass in a 1-g field, 11.9 µg rms over 2 h; and 1-g tumble bias repeatability over 5 cycles in 10 min, 2.64 µg rms, measured for a single cavity, with no common mode compensation.