Abstract: A system and method of monitoring a pressure, temperature, and/or vibration of a hostile environment without requiring the use of active electronics or an oscillator circuit in that environment. The system and method interrogate a resonant pressure sensor and a resonant or passive temperature sensor connected to a transmission line and located at least 100 feet (30.48 m) away from a network analyzer. The system and method use the reflected frequencies from the sensors to determine the pressure, temperature, and/or vibration. If the sensors are networked by the transmission line or a network filter, the reflected portion can include the reflected transmission energy. The applied signal and reflected portion travel along the transmission line, which is preferably impedance matched to that of the system. If a multi-conductor cable is used, the effects of the cable's length and temperature are compensated for via a system calibration when in field use.

Abstract: A capacitive pressure sensor includes a stator which encircles a portion of a cylindrical diaphragm. This encircling forms a circumferential gap between the sidewalls of the stator and the diaphragm. Therefore, a greater area “A” can be achieved in smaller diameter sensor footprint than prior art designs and yet still detect relatively small changes in capacitance. Additionally, the width “g1” of the gap can be wider than prior art designs without negatively affecting capacitance detection. A bonding agent which has a melting temperature of about half that of bonding agents used in prior art designs, secures the stator to the diaphragm and reduces oxidation issues during assembly, thereby decreasing manufacturing time and cost. To ensure proper side-to-side alignment of the stator relative to the diaphragm, a centering sleeve, which is removed after bonding, is placed over as stub at the upper end of the diaphragm.

Abstract: A system and method of monitoring a pressure, temperature, and/or vibration of a hostile environment without requiring the use of active electronics or an oscillator circuit in that environment. The system and method interrogate a resonant pressure sensor and a resonant or passive temperature sensor connected to a transmission line and located at least 100 feet (30.48 m) away from a network analyzer. The system and method use the reflected frequencies from the sensors to determine the pressure, temperature, and/or vibration. If the sensors are networked by the transmission line or a network filter, the reflected portion can include the reflected transmission energy. The applied signal and reflected portion travel along the transmission line, which is preferably impedance matched to that of the system. If a multi-conductor cable is used, the effects of the cable's length and temperature are compensated for via a system calibration when in field use.

Abstract: A capacitive pressure sensor includes a stator which encircles a portion of a cylindrical diaphragm. This encircling forms a circumferential gap between the sidewalls of the stator and the diaphragm. Therefore, a greater area “A” can be achieved in smaller diameter sensor footprint than prior art designs and yet still detect relatively small changes in capacitance. Additionally, the width “g1” of the gap can be wider than prior art designs without negatively affecting capacitance detection. A bonding agent which has a melting temperature of about half that of bonding agents used in prior art designs, secures the stator to the diaphragm and reduces oxidation issues during assembly, thereby decreasing manufacturing time and cost. To ensure proper side-to-side alignment of the stator relative to the diaphragm, a centering sleeve, which is removed after bonding, is placed over as stub at the upper end of the diaphragm.