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A capacitive sensor array is adapted to be disposed in a reservoir containing fluid or material along an axis of measurement of the fluid or material to determine the level of fluid or material contained within the reservoir. The sensor array includes a plurality of reference electrodes, wherein the

A capacitive sensor array is adapted to be disposed in a reservoir containing fluid or material along an axis of measurement of the fluid or material to determine the level of fluid or material contained within the reservoir. The sensor array includes a plurality of reference electrodes, wherein the capacitance of each of the electrodes varies in accordance both with the extent of the array's immersion in the fluid or material and the dielectric constant of the fluid or material. The plurality of reference electrodes preferably includes a lower electrode adapted to be immersed within the fluid or material in the reservoir and whose capacitance provides an estimate of the dielectric constant of the fluid or material contained within the reservoir. The reference electrodes also include an upper electrode adapted to be positioned above the fluid or material level that provides an estimate of the dielectric constant above the level of the fluid or material in the reservoir, and a middle electrode whose capacitance varies from a calibrated initial value to a value that is dependent on the level of and the dielectric constant of the fluid or material contained within the reservoir as determined from the capacitance of the lower electrode.

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A capacitive sensor array is adapted to be disposed in a reservoir containing fluid or material along an axis of measurement of the fluid or material to determine the level of fluid or material contained within the reservoir. The sensor array includes a plurality of reference electrodes, wherein the

A capacitive sensor array is adapted to be disposed in a reservoir containing fluid or material along an axis of measurement of the fluid or material to determine the level of fluid or material contained within the reservoir. The sensor array includes a plurality of reference electrodes, wherein the capacitance of each of the electrodes varies in accordance both with the extent of the array's immersion in the fluid or material and the dielectric constant of the fluid or material. The plurality of reference electrodes preferably includes a lower electrode adapted to be immersed within the fluid or material in the reservoir and whose capacitance provides an estimate of the dielectric constant of the fluid or material contained within the reservoir. The reference electrodes also include an upper electrode adapted to be positioned above the fluid or material level that provides an estimate of the dielectric constant above the level of the fluid or material in the reservoir, and a middle electrode whose capacitance varies from a calibrated initial value to a value that is dependent on the level of and the dielectric constant of the fluid or material contained within the reservoir as determined from the capacitance of the lower electrode. uter database search (2 pages). New Product Announcement: Sep. 1985, No. 0116075, located in computer database search. New Product Announcement: Jun. 1985, No. 101134, "Rf-10000 Series", located in computer database search. New Product Announcement: Jun. 1985, No.101132, "RF-7000", located in computer database search. Advertisement, "Wave Radar, " Level Transmitters, Dec. 1992, pp. 14 and 15. Kenneth Greywall, "Understanding Two-Wire Transmitters", Plant Engineering Magazine, Oct. 1, 1984, vol. 38, No. 23, pp. 2, 76-79. Merrill Skolnik, "Introduction to Radar Systems", pp. 68-100 (Chapter 3: CW and Frequency-Modulated Radar), 1988. "LB 432 Level Guage, FMCW-Radar for Continuous and non-Contact Level Measurement", EG&G Berthold News (no date), 4 pages. Douglas L. Duncan, "Ultrasonics in Solid Level Measurement". Advances in Instrumentation and Control, 46 (1991) Part 2, Research Triangle Park, North Carolina, pp. 1355-1366. New Product Announcement: Jan. 1987, No. 0153579, located in computer database search. New Product Announcement: Jun. 10, 1987, No. 0156975, located in computer database search. Robert Rosenberg and Tom Crumlish, "Two-Wire Field-Mounted Transmitters: Advantages and Problems", Advances in Instrumentation, vol. 40, Part 2, Proceedings of the ISA/85 International Conference and Exhibit, Oct. 21-24, 1985, pp. 1123-1128. John L. Daniewicz, "Using Radar Level Measurement For Increased Environmental Protection and Plant Safety" Advances in Instrumentation and Control 46 (1991) Part 2, Research Triangle Park, North Carolina, pp. 1201-1212. "Transmitters", Plant Engineering, Jul. 26, 1990, pp. 295-296. Jurgen Kehrbeck et al., "A Novel and Inexpensive Short Range FM-CW Radar Design", International Conference of Radar 1992, Brighton, UK, Oct. 12-13, 1992, pp. 288-291.