Capacitive gage pressure sensor with vacuum dielectric

A field device includes a capacitive gauge pressure sensor configured to measure a gage pressure of a process media. A sensor body of the pressure sensor includes first and second chambers. The second chamber is under vacuum and forms a vacuum dielectric for the pressure sensor. An atmospheric reference port is formed in the sensor body and maintains the first chamber in equilibrium with ambient atmospheric pressure. A process media inlet port of the sensor is configured to couple to a process media source. The sensor includes a conductive deflectable diaphragm between the second chamber and the media inlet port. A capacitive plate is disposed in the second chamber in relation to the diaphragm such that deflection of the diaphragm generates a change in capacitance. The field device also includes sensor circuitry which generates a sensor signal indicative of the gage pressure of the process media, and transmitter circuitry which transmits information relative to the sensor signal over a process communication loop.